[Research Progress on Estimation of Postmortem Submersion Interval]

Abstract

Postmortem interval （PMI） estimation is one of the most important and difficult academic tasks in forensic sciences. Due to the influence of the corpse itself and the water environment, corpses in water have unique corruption phenomenon and laws. Based on the experience of traditional PMI studies of corpses on land, forensic practitioners across the world have proposed a variety of practical methods for estimating postmortem submersion interval （PMSI）. This paper summarizes the literatures related to PMSI in recent years, and introduces methods to infer PMSI according to the phenomenon of corpses, the development of insects, the succession pattern of aquatic organisms, and the changes of other physical and chemical indexes of corpses, in order to provide some reference for the study of PMSI of corpses in water.

Guide to the Forensic Pathology Practice on Death Cases Related to Corona Virus Disease 2019 （COVID-19） （Trial Draft）

Abstract

Autopsy is of great significance to the elucidation of the pathological changes, pathogeneses and causes of death of corona virus disease 2019 （COVID-19） and can provide theoretical basis for more scientific and accurate prevention and control of the outbreak. Based on related laws and regulations, such as the Law of the People's Republic of China on Prevention and Control of Infectious Diseases, the clinical manifestations and epidemiological characteristics of COVID-19, and the related guidelines on the prevention and control of the outbreak, combined with the practical work of forensic pathology examination, the Guide to the Forensic Pathology Practice on Death Cases Related to Corona Virus Disease 2019 （COVID-19） （Trial Draft） has been developed. This guide includes information on the background investigation of the cases, autopsy room requirements, personal prevention and protections, external examinations, autopsy, auxiliary examinations, and so on. This guide can be used as a reference by forensic and pathological examination institutions, as well as examination staff.

Statistical Analysis of the Heart and Lung Mass in Forensic Anatomical Cases and Its Forensic Significance

Abstract

Objective To investigate the differences of heart mass and lung mass in forensic autopsy cases and to explore their application value in forensic identification. Methods The data from 1 614 autopsy cases accepted by center of Medico-legal Investigation of China Medical University between 2007 to 2016 were collected. The correlation of heart and lung mass with age, height, body weight, and body mass index （BMI）, as well as differences in different causes of death were analyzed by GraphPad Prism 6.0 software. Results The heart mass and lung mass of males were higher than those of females （P<0.05）. The heart mass of males and females was positively correlated with age, height, body weight and body mass index （BMI） （P<0.05）. The heart mass of patients dying from sudden cardiac death （SCD） was significantly higher than those dying from other causes of death. The lung mass of patients dying from drowning and delayed treatment was higher than those dying from other causes of death （P<0.05）. Conclusion In forensic practice, measurement of the heart mass and lung mass has certain significance for differential diagnosis and diagnosis of different causes of death.

Relationship between the Degeneration and Regeneration of Neuromuscular Junction and Wound Age during the Repair of Mouse Skeletal Muscle Contusion

Abstract

Objective To investigate the morphological changes in the degeneration and regeneration of neuromuscular junctions （NMJ） during the repair of mouse skeletal muscle contusion and discuss the correlation between the degeneration and regeneration of NMJ and wound age. Methods A total of 50 healthy adult male mice were randomly divided into 10 groups, including 9 experimental groups and 1 control group. Immunofluorescent staining was applied, and neurofilament was marked with neurofilament protein-H （NF-H）, presynaptic membrane was marked with synaptophysin （Syn）, presynaptic membrane was marked with acetylcholine receptor （AChR）. Morphological changes of NMJ regeneration at different time points after mouse skeletal muscle contusion were detected. Results The neurofilament and presynaptic membrane of NMJ at the junction of contusion zones began to degrade after contusion, and completed degradation at about 3 d post-injury. Then they gradually regenerated, roughly completing the regeneration at about 21 d and basically reaching the control group level. The ratio of presynaptic membrane quantity to presynaptic membrane quantity showed a trend of decreasing then rising and finally reaching the control level. Conclusion During the repair of mouse skeletal muscle contusion, the morphological changes and wound age of the NMJ at the junction of contusion zones have a close correlation, which is expected to be one of the biological indicators for forensic skeletal muscle wound age estimation.

Expression of Nrf2 in Different Cells after Human Cerebral Cortex Contusion

Abstract

Objective To observe the expression changes of nuclear factor-erythroid derived 2-related factors （Nrf2） in different cells at different time points after human cerebral cortex contusion, and to discuss its application in brain wound age estimation. Methods Thirty-six human brain tissues were selected, of which 6 were for control and 30 were cortical contusion at different time points post-injury, which were divided into 0-1 h, 3-6 h, 1-3 d, 5-7 d, and 10-14 d post-injury groups, with 6 cases in each group. Based on paraffin embedded sections, HE staining was used to observe the morphological changes post-injury, and double immunofluorescence staining was used to detect the expression of Nrf2 in neurons, astrocytes, and microglia. The number of positive cells was counted and statistical analysis was made. Results The number of neurons decreased 1-3 d post-injury. The expression of Nrf2 cells in neurons increased after injury, and the rate of positive cells peaked at 1-3 d post-injury. Glial cells were activated 1-3 d post-injury, and the activation peaked at 5-7 d post-injury. The cerebromalacia began to form at 10-14 d post-injury. Glial fibrillary acidic protein （GFAP） positive cells in mice increased gradually after injury and peaked at 5-7 d post-injury, while the proportion of Nrf2 in GFAP positive cells was relatively stable. After injury, ionized calcium-binding adapter molecule 1 （IBA1） positive cells increased and activated gradually. The expression proportion of Nrf2 in IBA1 positive cells increased gradually, reached its peak at 5-7 d post-injury, and then decreased. Conclusion The expression of Nrf2 in different cells involves in the biological function of different cells post-injury, and the dynamic expression of single cells has a time-dependent pattern. This may provide a new reference index for the wound age estimation of brain contusion in human.

Relationship between Changes of Pericyte Number and Wound Age during Repair of Skeletal Muscle Contusion in Mice

Abstract

Objective To observe the change pattern of pericyte number at different time periods after mice skeletal muscle contusion and discuss its role in wound age estimation. Methods A mice gastrocnemius muscle contusion model was established. The form and number changes of pericytes at 1, 3, 5, 7, 9, 14, and 28 d post-injury were detected by multiple immunofluorescence staining. Results Compared with the slender shape of pericytes in normal skeletal muscles, pericytes in the contusion area had increased volume, rounder form and a round nuclei. Part of pericytes were found to express satellite cell markers paired-box transcription factor （Pax7） or myoblast determination 1 （MyoD1）. The changes of pericyte number in skeletal muscles after contusion were time-dependant, and showed unimodal distribution with the extension of wound age. In the central contusion area, the number of pericytes peaked at 5 d post-injury while in the peripheral contusion area, the number of pericytes peaked at 5 d and 7 d post-injury. Conclusion The number of pericytes in contusion area varies time-dependently after skeletal muscle contusion in mice and might be a reference index for muscle wound age estimation, and is involved in the repair and regeneration of skeletal muscle injury.

Relationship between Expression Changes of CB2R and Wound Age of Brain Contusion in Mice

Abstract

Objective To investigate the expression of cannabinoid type 2 receptor （CB2R） at different time points after brain contusion and its relationship with wound age of mice. Methods A mouse brain contusion model was established with PCI3000 Precision Cortical Impactor. Expression changes of CB2R around the injured area were detected with immunohistochemical staining, immunofluorescent staining and Western blotting at different time points. Results Immunohistochemical staining results showed that only a few cells in the cerebral cortex of the sham operated group had CB2R positive expression. The ratio of CB2R positive cells gradually increased after injury and reached the peak twice at 12 h and 7 d post-injury, followed by a decrease to the normal level 28 d post-injury. The results of Western blotting were consistent with the immunohistochemical staining results. Immunofluorescent staining demonstrated that the changes of the ratio of CB2R positive cells in neurons, CB2R positive cells in monocytes and CB2R positive cells in astrocytes to the total cell number showed a single peak pattern, which peaked at 12 h, 1 d and 7 d post-injury, respectively. Conclusion The expression of CB2R after brain contusion in neurons, monocytes and astrocytes in mice suggests that it is likely to be involved in the regulation of the biological functions of those cells. The changes in CB2R are time-dependent, which suggests its potential applicability as a biological indicator for wound age estimation of brain contusion in forensic practice.

Research Progress?on?Age?Determination?of?Venous?Thrombosis in Forensic Medicine

Abstract

Pulmonary thromboembolism （PTE）, which is caused by detachment of venous thrombosis, is a common cause of sudden death in forensic practice. In the cases which die of PTE after trauma or die of PTE during non-thrombosis disease hospitalization, forensic pathologists are required to analyze the time sequence between trauma or medical practice and venous thrombosis, and then analyze their causal relationship. This review summarizes the history of thrombus age estimation and recent advances in forensic medicine, and then gives a brief outlook for future research to provide reference for forensic identification of PTE and guide follow-up studies.

[Forensic Analysis of 6 Cases of Sudden Death due to Hyperthyroid Heart Disease]

OBJECTIVES

To analyse the cases of sudden death due to hyperthyroid heart disease, and explore the general information of deaths and the forensic pathological characteristics to provide reference evidence for forensic identification of such cases.

METHODS

Six cases of sudden death due to hyperthyroid heart disease between 2001 and 2016 were selected from School of Forensic Medicine, China Medical University. The general information （gender and age）, clinical manifestations, medical history, anatomical and histopathological findings, biochemical parameters and cause of death were analysed retrospectively.

RESULTS

Most of the 6 patients had definite history of hyperthyroidism, and they all showed certain degrees of symptoms of cardiovascular disease; had obvious incentive factors of death; histopathological examination of thyroid conformed to the performances of diffuse toxic goiter; with increase of cardiac weight, dilatation of cardiac chambers, myocardial hypertrophy and focal necrosis; postmortem biochemical analyses of pericardial fluid could be used as an additional method for diagnostic of sudden death due to hyperthyroid heart disease.

CONCLUSIONS

The identification of death due to hyperthyroid heart disease should be based on the clinical history and the results of autopsy, histopathological examination, postmortem toxicology tests. The postmortem biochemical detection of thyroid and cardiac function should be performed if necessary.

Immunohistochemical detection of chemokines in human skin wounds and its application to wound age determination

Immunohistochemical studies on the time-dependent expression of the chemokines such as interleukin (IL)-8, monocyte chemoattractant protein (MCP)-1 and macrophage inflammatory protein (MIP)-1alpha were performed on 50 human skin wounds with different wound ages (group I 0-12 h, group II 1-4 days, group III 7-14 days and group IV 17-21 days). In the wound specimens with wound ages between 4 and 12 h, neutrophils mainly showed positive reactions for IL-8, MCP-1 and MIP-1alpha. With increasing wound ages, macrophages and fibroblasts were positively stained with anti-IL-8, MIP-1alpha and MCP-1 antibodies. Morphometrically, there was a similar distribution in the positive ratios of the inflammatory cells among IL-8, MCP-1 and MIP-alpha. The positive ratios of each chemokine were very low in group I and a considerable increase of the positive ratios in each chemokine was observed in group II (mean +/- standard error IL-8: 59.8 +/- 2.1%, MCP-1: 42.4 +/- 3.1% and MIP-1alpha: 50.4 +/- 3.7%). Although the positive ratios for each chemokine gradually decreased according to the wound age, the mean positive ratios in groups III and IV were significantly higher than those in group I. From the forensic aspect, these chemokines are considered useful markers for wound age determination. Thus, ratios of > 50% for IL-8, > 30% for MCP-1 or > 40% for MIP-1alpha indicate a wound age of at least I day. Moreover, the combined investigation of these three chemokines can make wound age determination more objective and accurate.

Immunohistochemical study on Fas and Fas ligand in skin wound healing

An immunohistochemical study on the expression of Fas and Fas ligand (Fas L) was performed in order to examine the role of apoptosis through Fas-Fas L in mouse skin wound healing. After a 1-cm-long incision in the central dorsum skin, mice were sacrificed at intervals ranging from 0.5 to 240 h, followed by the sampling of wound margin. The expression of Fas and Fas L in the wound margins and in uninjured skin controls was studied using frozen sections. In uninjured skin controls, a very weak expression of Fas and Fas L was detected immunohistochemically in hair follicles, sebaceous glands and epidermal cells. In wounded specimens, polymorphonuclear cells and inflammatory mononuclear ones (round-shaped and spindle-shaped types) were evident. A single immunostaining showed that Fas or Fas L was detectable in inflammatory mononuclear cells involved in the skin wound healing process. Double immunostaining for Fas and Fas L revealed that inflammatory mononuclear cells co-expressed both antigens. In situ TUNEL combined with immunostaining showed that the inflammatory mononuclear cells expressing Fas or Fas L and the polymorphonuclear cells were TUNEL-stained, although neither Fas nor Fas L was detected in the polymorphonuclear cells. The number of TUNEL-positive, inflammatory mononuclear cells expressing Fas or Fas L per 0.01 x 0.01 cm2 was counted. The average number of 10 randomly selected microscope fields reached a peak at the fibro-proliferative phase of wound healing. These results indicate that apoptosis through Fas and Fas L may play an important role for reducing the cellularity during skin wound healing in mice.

Morphological findings of 'cardiac concussion' due to experimental blunt impact to the precordial region

The dog's precordial region at the sternum was impacted with a mechanical elastic-cord propelled impactor at the velocity of 8.0 m/s. The left and right intraventricular pressures and electrocardiogram (ECG) were monitored continuously for 60 min after the impact. The micro- and ultra-structure of myocardium were examined. Localization of myocardial myoglobin (Mb), creatine kinase BB (CK-BB) and creatine kinase MM (CK-MM) as well as plasma membrane permeability were studied by immunohistochemical and lanthanum probe techniques. Upon the impact, abrupt over-pressures within both ventricles were recorded with transient depression of the left ventricular systolic pressure. In all the dogs, some rhythm- and conduction-disorders were noted, which lasted transiently and resumed to normal sinus rhythm. At autopsy, no gross injuries of the heart were detected, and microscopic examination showed no visible myocardial lesions. However, immunohistochemically, focal patchy loss of myocardial Mb, CK-BB and CK-MM was identified with scattered deposition of these substances between myocardial fibers elsewhere. Such changes as relaxed myofibrils with widened I band, contracted myofibrils and broken cristae of the mitochondria were observed in myocardial ultrastructure. Lanthanum particles deposited inside the mitochondria. These results indicate that increase in cardiac cell membrane permeability and ultrastructural damage in myocardium may be involved even in cardiac concussion.

[Degradation of liquid preparations of four fluoroquinolones by factorial experiment. ]

The effects of light, pH and ionic strength on the degradation of four fluoroquinolones (norfloxacin, NFX; ofloxacin, OFX; ciprofloxacin, CPX; lomefloxacin, LEMX) solutions were studied. Using 2(3) factorial experiment and F test, it was confirmed that the degradation of NFX, OFX, CPX and LEMX was affected very markedly by light, but almost not affected by the ionic strength of the solution. The degradation of OFX and CPX was affected very markedly by pH, but the degradation of NFX and LEMX was almost not affected by pH. The degradation of OFX and CPX was affected very markedly by the combined action of light and pH, but the degradation of NFX and LEMX was almost not affected by the combined action of light and pH.

Changes of myocardial myoglobin, myosin and creatine kinase in cases of sudden nocturnal death syndrome

Myoglobin, myosin creatine kinase MM (CK-MM), creatine kinase BB(CK-BB) in cardiac muscle and H chain of myosin in atrial and ventricular muscle were studied in specimens from 8 patients who died of sudden nocturnal death syndrome (SNDS) by avidin-biotin complex (ABC) method to investigate the possible early or very early myocardial ischemia in the syndrome. Hematoxylin-eosin staining was conducted for comparison. The results showed evident loss of CK-MM, CK-BB, myoglobin and myosin from cardiac muscle cells, indicating that occurrence of SNDS is closely associated with acute myocardial ischemia.