The current macroscopical and microscopical signs in the fresh drowning victim are non-specific. Moreover, putrefaction will vanish these autopsy findings quite rapidly. The study of additional detecting methods to diagnose drowning has become one of the hottest topics in forensic medicine. This article reviewed several methods commonly used in the determination of drowning in forensic practice. The advantages and disadvantages of various methods were also discussed.
Chlorophyll/isolation & purification* ; Chlorophyll A ; Diatoms/isolation & purification* ; Drowning/diagnosis* ; Forensic Medicine ; Humans ; Lung/chemistry*

OBJECTIVETo compare the efficacy of three methods for forensic diatom test, namely strong acid digestion-centrifuge enrichment-light microscopy (SD-CE-LM), microwave digestion-membrane filtration-automated scanning electron microscopy (MD-ME-SEM), and microwave digestion-membrane filtration-light microscopy (MD-MF-LM).

METHODSSixty samples were randomly divided into 3 groups for diatom test using three methods, and the sample preparation time, degree of digestion and recovery rate of diatoms were compared.

RESULTSThe sample preparation time was the shortest with MD-MF-LM and the longest with SD-CE-LM (P<0.05). MD-ME-SEM and MD-MF-LM allowed more thorough tissue digestion than SD-CE-LM. MD-ME-SEM resulted in the highest total recovery rate of diatom, followed by MD-MF-LM and then by SD-CE-LM (P<0.05); the recover rate of different diatom species was the highest with MD-ME-SEM, followed by MD-MF-LM and SD-CE-LM (P<0.05).

CONCLUSIONSD-CE-LM has a low recovery rate of diatoms especially for those with lengths shorter than 40 µm or densities less than 1/5. With a high recovery rate and accuracy in diatom test, MD-ME-SEM is suitable for diagnosis of suspected drowning cases. MD-MF-LM is highly efficient, sensitive and convenient for forensic diatom test.

Centrifugation ; Diatoms ; isolation & purification ; Drowning ; Forensic Sciences ; methods ; Humans ; Microscopy ; Microscopy, Electron, Scanning ; Microwaves ; Specimen Handling

OBJECTIVE: To investigate the numbers, sizes and types distribution of diatoms in drowned and postmortem immersed rabbits' lungs. METHODS: Sixty-two rabbits were randomly divided into drowning group (n = 30), postmortem immersion group (n = 30) and land death group (n=2), and the diatoms in each lung lobe were analyzed quantitatively and qualitatively by microwave digestion and scanning electron microscopy. RESULTS: In the drowning group, the diatoms were detected in each lung lobe with Cyclotella and Melosira in the majority. In the postmortem immersion group, Cyclotella was in the majority. And the diatoms weren't detected in some lung lobes in postmortem immersion. There were significant differences in the detection rates of upper lobe of left lung, middle lobe and cardiac lobe of right lung in two groups (P < 0.05). CONCLUSION Based on the microwave digestion and scanning electron microscopy, the numbers, sizes and types distribution of diatoms in drowned and postmortem immersed rabbits' lungs can be analyzed and used as references for testing theory.
Animals ; Autopsy ; Diatoms/isolation & purification* ; Drowning ; Lung/microbiology* ; Microscopy, Electron, Scanning ; Microwaves ; Rabbits

In drowning cases, it is difficult to judge whether the deceased died from drowning or throwing into the water after killed or identificate the cause of death of the decomposed corps in forensic practices. The diatom test is still considered as the important assistant evidence in drowning cases. This paper reviews research progress on technologies in recent years of forensic diatom test, and the application value of the new developing approach in the field of forensic medicine.
Autopsy/methods* ; Cause of Death ; Diatoms/isolation & purification* ; Drowning/diagnosis* ; Forensic Medicine ; Humans

OBJECTIVES: To detect diatom in the organs of drowners by enzyme combined with strong acid digestion method, and evaluate its application value. METHODS: A total of 40 cases which have been identified as drowning in local region were collected. Samples of the lung, liver, kidney, and the water of the scene were also gathered from each case. Strong acid digestion method, enzyme combined with strong acid digestion method, and enzymic digestion method were respectively performed to detect the diatom in the samples. The comparative analysis was made on digestion time, digestive power and detection rate of diatom, etc. RESULTS: Enzyme combined with strong acid digestion method was significantly better than enzymic digestion method on digestion time and digestive power; enzyme combined with strong acid digestion method were obviously superior to strong acid digestion method on the detection rate of diatom. CONCLUSIONS Enzyme combined with strong acid digestion method combines the advantages of strong acid digestion method and enzymic digestion method. It has the characters of operation safety with little pollution to environment, which is worthy of further popularization and practice.
Diatoms/isolation & purification* ; Drowning ; Forensic Pathology/methods* ; Humans ; Kidney/metabolism* ; Liver/metabolism* ; Lung/metabolism*

OBJECTIVE: To explore the quantity and distribution of diatoms in main rivers and lakes in Xicheng, Dongcheng, Chaoyang, Haidian, Fengtai and Shijingshan Districts of the city of Beijing. METHODS: Water samples were examined through the method of disorganizing, which were collected from 16 rivers and lakes in the central city of Beijing in September and October 2011. Diatom species and proportions of water samples were analyzed using DotSlide microscope station. RESULTS: A total of 10 species of diatoms were detected. Cyclotella, Synedra and Melosira etc. were found to be the dominant species via quantitative analysis. Significant differences were observed for diatom species and proportions among the different rivers and lakes. Melosira was found to be the dominant species in the Chang River; Synedra, in the Zhuan River, the Kunyu River and the Taoranting Park; Cyclotella, in the East Moat River, the Ba River, the Liangshui River and the Yongding River; and Navicula, in the Liangma River; Nitzschia, in the diversion canal of the Yongding River. CONCLUSION The features of distribution of diatoms in the central city of Beijing are outlined. The morphological and relative constituent ratio database of diatoms are established in central city of Beijing.
Biodiversity ; China ; Cities ; Diatoms/isolation & purification* ; Ecosystem ; Forensic Medicine/methods* ; Fresh Water/analysis* ; Phytoplankton/isolation & purification* ; Rivers ; Species Specificity

OBJECTIVE: To investigate the advantages of nitric acid digestion method and its differences with the traditional method. METHODS: Ethanol was used to fully fix the testing sample. About 80-100 g of the testing samples were cut into pieces and digested with nitric acid. It was then centrifuged and washed to remove organic components. Smears were prepared and examined under the light microscope. RESULTS: The diatom had been identified with clear striations, counted conveniently and classified easily. CONCLUSION The improved nitric acid digestion method is not only simple with a higher successful rate of detection, but also can prevent interference from contamination. It can improve the stability of the experimental results, avoid harm to human and environment, and provide higher safety in the course of experiment.
Autopsy ; Diatoms/isolation & purification* ; Drowning ; Forensic Pathology ; Humans ; Kidney/metabolism* ; Liver/metabolism* ; Lung/metabolism* ; Nitric Acid/chemistry* ; Postmortem Changes ; Tissue Fixation/methods*

OBJECTIVE: To explore potential application of diatom test of lung tissue in investigation of cause of death in victim found in the water. METHODS: Four hundred and seven cases were collected and analyzed for cause of death and the nature of case. Diatom test was performed in tissues and the amount was quantified. Forty-five rabbits died in the water (antemortem, postmortem and different seasons drowning) were randomly divided into 9 groups and the diatom content in lung tissue were tested with the method of nitric acid. RESULTS: In 407 drowning cases, 372 cases showed a positive result of diatom test. In positive cases, the amount of accidents or suicide were 35 and homicide were 21. Thirty-five cases showed negative result of diatom test and majority were homicide in which bodies were thrown into the water after killing. Some drowning cases were in special circumstances. Animal experiments confirmed that a large amount of diatoms in lung tissue were detected in drowning victim and showed the same type in water. The amount of diatom in lung tissue was usually lower in the summer and winter comparing with spring and autumn. CONCLUSION The diatom test could be considered as an auxiliary evidence in determination of cause of death in body found in the water. The test results were related with manner of death. The nature of case should be synthetically determined based on autopsy, criminal scene and details of the cases, etc.
Animals ; Cadaver ; Cause of Death ; Diatoms/isolation & purification* ; Drowning/diagnosis* ; Female ; Forensic Pathology/methods* ; Fresh Water ; Humans ; Liver/pathology* ; Lung/pathology* ; Male ; Rabbits ; Seasons ; Tissue Distribution

OBJECTIVETo establish a method for amplifying specific 16S rDNA fragment of algae related with drowning and test its value in drowning diagnosis.

METHODSThirty-five rabbits were randomly divided into 3 the drowning group (n=15), postmortem water immersion group (n=15, subjected to air embolism before seawater immersion), and control group(n=5, with air embolism only). Twenty samples of the liver tissues from human corpses found in water were also used, including 14 diatom-positive and 6 diatom-negative samples identified by microwave digestion-vacuum filtration-automated scanning electron microscopy (MD-VF-Auto SEM). Seven known species of algae served as the control algae (Melosira sp, Nitzschia sp, Synedra sp, Navicula sp, Microcystis sp, Cyclotella meneghiniana, and Chlorella sp). The total DNA was extracted from the tissues and algae to amplify the specific fragment of algae followed by 8% polyacrylamide gelelectrophoresis and sliver-staining.

RESULTSIn the drowning group, algae was detected in the lungs (100%), liver (86%), and kidney (86%); algae was detected in the lungs in 2 rabbits in the postmortem group (13%) and none in the control group. The positivity rates of algae were significantly higher in the drowning group than in the postmortem group (P<0.05). Of the 20 tissue samples from human corps found in water, 15 were found positive for algae, including sample that had been identified as diatom-negative by MD-VF-Auto SEM. All the 7 control algae samples yielded positive results in PCR.

CONCLUSIONSThe PCR-based method has a high sensitivity in algae detection for drowning diagnosis and allows simultaneous detection of multiple algae species related with drowning.

Animals ; Autopsy ; Cadaver ; DNA, Ribosomal ; isolation & purification ; Diatoms ; genetics ; Drowning ; diagnosis ; Electrophoresis, Polyacrylamide Gel ; Humans ; Kidney ; Liver ; Lung ; Microscopy, Electron, Scanning ; Polymerase Chain Reaction ; RNA, Ribosomal, 16S ; isolation & purification ; Rabbits

OBJECTIVE: To compare and explore the application value of diatom nitric acid digestion method and plankton 16S rDNA PCR method for drowning identification. METHODS: Forty drowning cases from 2010 to 2011 were collected from Department of Forensic Medicine of Wenzhou Medical University. Samples including lung, kidney, liver and field water from each case were tested with diatom nitric acid digestion method and plankton 16S rDNA PCR method, respectively. The Diatom nitric acid digestion method and plankton 16S rDNA PCR method required 20 g and 2 g of each organ, and 15 mL and 1.5 mL of field water, respectively. The inspection time and detection rate were compared between the two methods. RESULTS: Diatom nitric acid digestion method mainly detected two species of diatoms, Centriae and Pennatae, while plankton 16S rDNA PCR method amplified a length of 162 bp band. The average inspection time of each case of the Diatom nitric acid digestion method was (95.30 +/- 2.78) min less than (325.33 +/- 14.18) min of plankton 16S rDNA PCR method (P < 0.05). The detection rates of two methods for field water and lung were both 100%. For liver and kidney, the detection rate of plankton 16S rDNA PCR method was both 80%, higher than 40% and 30% of diatom nitric acid digestion method (P < 0.05), respectively. CONCLUSION The laboratory testing method needs to be appropriately selected according to the specific circumstances in the forensic appraisal of drowning. Compared with diatom nitric acid digestion method, plankton 16S rDNA PCR method has practice values with such advantages as less quantity of samples, huge information and high specificity.
Adolescent ; Adult ; DNA, Ribosomal/genetics* ; Diatoms/isolation & purification* ; Drowning/diagnosis* ; Female ; Forensic Medicine/methods* ; Fresh Water/analysis* ; Humans ; Kidney ; Liver ; Lung ; Male ; Middle Aged ; Nitric Acid ; Plankton/isolation & purification* ; Polymerase Chain Reaction/methods* ; RNA, Ribosomal, 16S/genetics* ; Young Adult