Candidate biomarkers in brown adipose tissue for post-mortem diagnosis of fatal hypothermia

Post-mortem diagnosis of fatal hypothermia (FHT) is challenging in forensic practice because traditional morphological and biochemical methods lack specificity. Recent studies have reported that brown adipose tissue (BAT) is activated during cold-induced non-shivering thermogenesis in mammals, but BAT has not been used to diagnose FHT. The aim of this study was to identify novel biomarkers in BAT for FHT based on morphological changes and differential protein expression. Two FHT animal models were created by exposing mice to 4 or -20 °C at 50% humidity. Morphologically, the unilocular lipid droplet content was significantly increased in BAT of FHT model mice compared with that of control mice. Proteomics analysis revealed a total of 283 and 266 differentially expressed proteins (DEPs) between the 4 or -20 °C FHT subgroups and control group, respectively. In addition, 140 proteins were shared between the FHT subgroups. GO and KEGG analyses revealed that the shared DEPs were mainly enriched in pathways associated with metabolism, oxidative phosphorylation, and thermogenesis. Further screening (|log2FC| > 1.6, q-value (FDR) < 0.05) identified GMFB, KDM1A, DDX6, RAB1B, SHMT-1, CLPTM1, and LMF1 as candidate biomarkers of FHT. Subsequent validation experiments were performed in FHT model mice using classic immunohistochemistry and western blotting. RAB1B and GMFB expression was further verified in BAT specimens from human cases of FHT. The results demonstrate that BAT can be used as a target organ for FHT diagnosis employing RAB1B and GMFB as biological markers, thus providing a new strategy for the post-mortem diagnosis of FHT in forensic practice.

Inferring Postmortem Submersion Interval in Rats Found in Water Based on Vitreous Humor Metabolites

OBJECTIVES

The metabolomics technique of LC-MS/MS combined with data analysis was used to detect changes and differences in metabolic profiles in the vitreous humor of early rat carcasses found in water, and to explore the feasibility of its use for early postmortem submersion interval (PMSI) estimation and the cause of death determination.

METHODS

The experimental model was established in natural lake water with 100 SD rats were randomly divided into a drowning group (n=50) and a postmortem (CO₂ suffocation) immediately submersion group (n=50). Vitreous humor was extracted from 10 rats in each group at 0, 6, 12, 18 and 24 h postmortem for metabolomics analyses, of which 8 were used as the training set to build the model, and 2 were used as test set. PCA and PLS multivariate statistical analysis were performed to explore the differences in metabolic profiles among PMSI and causes of death in the training set samples. Then random forest (RF) algorithm was used to screen several biomarkers to establish a model.

RESULTS

PCA and PLS analysis showed that the metabolic profiles had time regularity, but no differences were found among different causes of death. Thirteen small molecule biomarkers with good temporal correlation were selected by RF algorithm. A simple PMSI estimation model was constructed based on this indicator set, and the data of the test samples showed the mean absolute error (MAE) of the model was 0.847 h.

CONCLUSIONS

The 13 metabolic markers screened in the vitreous humor of rat corpses in water had good correlations with the early PMSI. The simplified PMSI estimation model constructed by RF can be used to estimate the PMSI. Additionally, the metabolic profiles of vitreous humor cannot be used for early identification of cause of death in water carcasses.

Application Prospect of MicroRNA in Skin Wound Age Estimation

Wound age estimation is one of the major tasks in forensic practice. However, relatively accurate estimation of the wound age is still a conundrum and research spotlight world-widely. Studies show that microRNAs (miRNAs) are involved in the whole process of the skin wound repair, and miRNAs, as biomarkers, might be used to estimate the time of skin injury owing to their characteristic advantage. This paper summarizes the miRNA fundamental function, properties, current research progress in the estimation of wound age, and its limitations, and put forward prospect of potential application and research based on miRNAs in estimation of wound age.

[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.

The distribution and time-dependent expression of HIPK2 during the repair of contused skeletal muscle in mice

HIPK2 is an evolutionarily conserved serine/threonine kinase and is considered a co-regulator of an increasing number of transcription factors modulating a variety of cellular processes, including inflammation, proliferation and fibrosis. Skeletal muscle injuries repair is an overlapping event between inflammation and tissue repair. There are no reports about HIPK2 expression in skeletal muscles after trauma. A foundational study on distribution and time-dependent expression of HIPK2 was performed by immunohistochemical staining, Western blotting and quantitative real-time PCR, which is expected to obtain a preliminary insight into the functions of HIPK2 during the repair of contused skeletal muscle in mice. An animal model of skeletal muscle contusion was established in 50 C57B6/L male mice. Samples were taken at 1, 3, 5, 7, 9, 14, 17, 21 and 28 days after contusion, respectively (5 mice at each posttraumatic interval). 5 mice were employed as control. No HIPK2-positive staining was detected in uninjured skeletal muscle. Intensive immunoreactivties of HIPK2 were observed in polymorphonuclear cells, round-shaped mononuclear cells, regenerated multinucleated myotubes and spindle-shaped fibroblastic cells in the contused tissue. The HIPK2-positive cells were identified as neutrophils, macrophages and myofibroblasts by double immunofluorescent procedure. HIPK2 protein and mRNA expression were remarkably up-regulated after contusion by Western blotting and qPCR analysis. The results demonstrated that the expression of HIPK2 is distributed in certain cell types and is time-dependently expressed in skeletal muscle after contusion, which suggested that HIPK2 may participate in the whole process of skeletal muscle wound healing, including inflammatory response, muscle regeneration and fibrogenesis.

Cannabinoid 2 receptor attenuates inflammation during skin wound healing by inhibiting M1 macrophages rather than activating M2 macrophages

Background

The anti-inflammatory properties of the cannabinoid 2 receptor (CB2R) in injury and inflammatory diseases have been widely substantiated. Specifically, the anti-inflammatory effect of CB2R may be achieved by regulating macrophage polarisation. Several research findings suggested that the activation of CB2R could attenuate inflammation by reducing pro-inflammatory M1 macrophage polarisation and promoting anti-inflammatory M2 polarisation. However, considering CB2R inhibits fibrosis and M2 promotes fibrosis, that the activation of CB2R may lead to an increase in M2 macrophages seems contradictory. Therefore, we hypothesised that the activation of CB2R to attenuate inflammation is not achieved by up-regulating M2 macrophages.

Methods

We established an incised wound model using mouse skin and used this to evaluate the effect of CB2R agonists (JWH133 or GP1a) and an antagonist (AM630) on wound healing. At various post-injury intervals, we used western blot analysis, immunofluorescence staining, enzyme-linked immunosorbent assay and quantitative reverse transcription polymerase chain reaction assays to determine CB2R protein expression, M1/M2 macrophage infiltration, and the protein and gene expression of M1/M2-associated markers and cytokines in skin lesions.

Results

Activation of CB2R significantly reduced M1 macrophage infiltration and slightly increased M2 macrophage infiltration. Similarly, gene expression and protein levels of M1-associated markers and cytokines (interleukin [IL]-6, IL-12, CD86 and inducible nitric oxide synthase) were significantly down-regulated after CB2R agonist administration; in contrast, markers and cytokines were increased in the CB2R antagonist–treated group. Conversely, the administration of agonists slightly increased gene expression and protein levels of M2-associated markers and cytokines (IL-4, IL-10, CD206 and arginase-1 [Arg-1]); however, a statistical significance at most time points post-injury was not noted.

Conclusion

In summary, our findings suggested that during incised skin wound healing in mice, increased levels of CB2R may affect inflammation by regulating M1 rather than M2 macrophage subtype polarisation. These results offer a novel understanding of the molecular mechanisms involved in the inhibition of inflammation by CBR2 that may lead to new treatments for cutaneous inflammation.

[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.

Pharmacological activation of cannabinoid 2 receptor attenuates inflammation, fibrogenesis, and promotes re-epithelialization during skin wound healing

Previous studies showed that cannabinoid 2 (CB2) receptor is expressed in multiple effector cells during skin wound healing. Meanwhile, its functional involvement in inflammation, fibrosis, and cell proliferation in other organs and skin diseases implied CB2 receptor might also regulate skin wound healing. To verify this hypothesis, mice excisional wounds were created and treated with highly selective CB2 receptor agonist GP1a (1-(2,4-dichlorophenyl)-6-methyl- N-piperidin-1-yl-4H-indeno[1,2-c]pyrazole-3-carboxamide) and antagonist AM630 ([6-iodo-2- methyl-1-(2-morpholin-4-ylethyl)indol-3-yl]-(4-methoxyphenyl)methanone) respectively. The inflammatory infiltration, cytokine expression, fibrogenesis, and wound re-epithelialization were analyzed. After CB2 receptor activation, neutrophil and macrophage infiltrations were reduced, and expressions of monocyte chemotactic protein (MCP)-1, stromal cell-derived factor (SDF)-1, Interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β1 and vascular endothelial growth factor (VEGF)-A were decreased. Keratinocyte proliferation and migration were enhanced. Wound re-epithelialization was accelerated. Fibroblast accumulation and fibroblast-to-myofibroblast transformation were attenuated, and expression of pro-collagen I was decreased. Furthermore, HaCaT cells in vitro were treated with GP1a or AM630, which revealed that CB2 receptor activation promoted keratinocyte migration by inducing the epithelial to mesenchymal transition. These results, taken together, indicate that activating CB2 receptor could ameliorate wound healing by reducing inflammation, accelerating re-epithelialization, and attenuating scar formation. Thus, CB2 receptor agonist might be a novel perspective for skin wound therapy.

Cannabinoid CB₂ receptors are involved in the regulation of fibrogenesis during skin wound repair in mice

Studies have shown that cannabinoid CB2 receptors are involved in wound repair, however, its physiological roles in fibrogenesis remain to be elucidated. In the present study, the capacity of cannabinoid CB2 receptors in the regulation of skin fibrogenesis during skin wound healing was investigated. To assess the function of cannabinoid CB2 receptors, skin excisional BALB/c mice were treated with either the cannabinoid CB2 receptor selective agonist, GP1a, or antagonist, AM630. Skin fibrosis was assessed by histological analysis and profibrotic cytokines were determined by immunohistochemistry, immunofluorescence staining, reverse transcription‑quantitative polymerase chain reaction and immunoblotting in these animals. GP1a decreased collagen deposition, reduced the levels of transforming growth factor (TGF)‑β1, TGF‑β receptor I (TβRI) and phosphorylated small mothers against decapentaplegic homolog 3 (P‑Smad3), but elevated the expression of its inhibitor, Smad7. By contrast, AM630 increased collagen deposition and the expression levels of TGF‑β1, TβRI and P‑Smad3. These results indicated that cannabinoid CB2 receptors modulate fibrogenesis and the TGF‑β/Smad profibrotic signaling pathway during skin wound repair in the mouse.

Time-dependent Expression of MMP-2 and TIMP-2 after Rats Skeletal Muscle Contusion and Their Application to Determine Wound Age

The ability to determine vitality and estimate the survival period after a wound is critical in routine forensic practice. The mRNA levels of MMP-2 and TIMP-2 were examined using quantitative real-time RT-PCR to determine the age of a wound. Furthermore, the colocalization of them with Macrophage Marker, respectively, was detected by double immunofluorescence, and a standardized rat model of skeletal muscle contusion was established. In the antemortem contused groups, a large number of macrophages showed positive staining for MMP-2 and TIMP-2, and the expression of MMP-2 and TIMP-2 mRNA increased sharply at 3 days postinjury, with relative quantities of 5.75 and 2.98. No samples in the other groups showed relative quantities of >5.75 and 2.98; therefore, relative quantities exceeding 5.75 and 2.98 were strongly indicated 3 days after contusion. In addition, there was a significant decrease in the relative quantity in the postmortem contused groups, indicating that they were useful for diagnosing vitality.

Detection of satellite cells during skeletal muscle wound healing in rats: time-dependent expressions of Pax7 and MyoD in relation to wound age

The study was focused on time-dependent expressions of paired-box transcription factor 7 (Pax7) and myoblast determination protein (MyoD) during skeletal muscle wound healing. An animal model of skeletal muscle contusion was established in 40 Sprague-Dawley male rats. Samples were taken at 1, 3, 5, 7, 9, 13, 17, and 21 days after injury, respectively (five rats in each posttraumatic interval). Five rats were employed as control. By morphometric analysis, the data based on the number of Pax7(+)/MyoD(-), Pax7(+)/MyoD(+), and Pax7(-)/MyoD(+) cells were highly correlated with the wound age. Pax7 and MyoD expressions were upregulated after injury by Western blot and quantitative real-time PCR assays. The relative quantity of Pax7 protein peaked at 5 days after injury, which was >1.13, and decreased thereafter. Similarly, the relative quantity of MyoD mRNA expression peaked at 3 days after injury, which was >2.59. The relative quantity of Pax7 protein >0.73 or mRNA expression >2.38 or the relative quantity of MyoD protein >1.33 suggested a wound age of 3 to 7 days. The relative quantity of MyoD mRNA expression >2.02 suggested a wound age of 1 to 7 days post-injury. In conclusion, the expressions of Pax7 and MyoD are upregulated in a time-dependent manner during skeletal muscle wound healing, suggesting that Pax7 and MyoD may be potential markers for wound age estimation in skeletal muscle.

The distribution and time-dependent expression of MAGL during skeletal muscle wound healing in rats

Monoacylglycerol lipase (MAGL) is widely distributed in mammals and largely responsible for metabolizing 2-arachidonoylglycerol (2-AG). Little is known about its expression in skeletal muscles after trauma. A preliminary study on time-dependent expression and distribution of MAGL was performed by immunohistochemical staining, Western blotting and quantitative real-time PCR (qPCR) during skeletal muscle wound healing in rats. An animal model of skeletal muscle contusion was established in 40 Sprague-Dawley male rats. Samples were taken at 1, 3, 5, 7, 9, 13, 17 and 21 days after contusion, respectively (5 rats in each posttraumatic interval). 5 rats were employed as control. Weak immunoreactivity of MAGL was observed in the sarcoplasm of myofibers in control rats. Intensive immunoreactivities of MAGL were observed in polymorphonuclear cells (PMNs), round-shaped mononuclear cells (MNCs), spindle-shaped fibroblastic cells (FBCs) and regenerated multinucleated myotubes in the injured tissue. Subsequently, neutrophils, macrophages and myofibroblasts were identified as MAGL-positive cells by double immunofluorescent procedure. MAGL expression was remarkably up-regulated after contusion by qPCR and Western blot analysis. The results demonstrate that the expression of MAGL is distributed in certain cell types and time-dependently expressed in skeletal muscles after trauma, suggesting that MAGL may be involved in inflammatory response, fibrogenesis and muscle regeneration during skeletal muscle wound healing.

CB2R orchestrates fibrogenesis through regulation of inflammatory response during the repair of skeletal muscle contusion

Skeletal muscle injuries repair typically is an overlapping event between inflammation and tissue repair. Our previous study has demonstrated that activation of cannabinoid receptor type 2 (CB2R) by JWH-133 alleviates fibrosis in the repair of rat skeletal muscle contusion. Meanwhile, accumulated data show that CB2R stimulation exerts anti-inflammatory property in sepsis and cystitis. However, the effects of CB2R on inflammatory cytokines in response to the repair of skeletal muscle contusion are still unknown. In this study, we used selective agonist or antagonist of CB2R to observe the role of CB2R on inflammation and fibrogenesis during the repair of contused skeletal muscles in rats. Our results revealed that treatment with Gp1a, a selective CB2R agonist, significantly decreased the infiltration of neutrophils and macrophages, the expression of pro-inflammatory cytokines MCP-1, TNF-α, IL-1β and IL-6, the expression of pro-fibrotic cytokines IL-4, IL-13, TGF-β and P-Smad3 while increased anti-fibrotic cytokine IL-10 production as compared with Vehicle. The opposite results were observed in the CB2R inhibition group with AM630. Our study demonstrated that CB2R orchestrates fibrogenesis through regulation of inflammatory response during the repair of skeletal muscle contusion.

Time-dependent appearances of myofibroblasts during the repair of contused skeletal muscle in rat and its application for wound age determination

OBJECTIVE

To research the relation between the time-dependent appearances of myotibroblasts during the repair of contused skeletal muscle in rat and wound age determination.

METHODS

A total of 35 SD male rats were divided into the control and six injured groups according to wound age as follows: 12 h, 1 d, 5 d, 7 d, 10 d and 14 d after injury. The appearances of myofibroblasts were detected by HE staining, immunohistochemistry and confocal laser scanning microscopy. Masson's trichrome staining was utilized to examine collagen accumulation in the contused areas.

RESULTS

Immunohistochemical staining showed that α-SMA+ myofibroblasts were initially observed at 5 d post-injury. The average ratio of myofibroblasts was highest at 14 d post-injury, with all samples, ratios more than 50%. In the other five groups, the average of α-SMA positive ratios were less than 50%. The collagen stained areas in the contused zones, concomitant with myofibroblast appearance, were increasingly augmented along with advances of posttraumatic interval.

CONCLUSION

The immunohistochemical detection of myofibroblasts can be applied to wound age determination. The myofibroblasts might be involved in collagen deposition during the repair of contused skeletal muscle in rat.

[Correlation between percentages of PMN, MNC, FBC and wound age after skeletal muscle injury in rats]

OBJECTIVE

To study the percentages of polymorphonuclear leukocytes (PMN), mononuclear cells (MNC) and fibroblastic cells (FBC) in different post-traumatic intervals after skeletal muscle mechanical injury in rats.

METHODS

The rat model of skeletal muscle mechanical injury was established. The rats were divided into injured groups (6 h, 12 h, 1 d, 3 d, 7 d, 10 d and 14 d after injury) and control group. The percentages of PMN, MNC and FBC in different post-traumatic intervals after skeletal muscle mechanical injury were assessed with HE staining and image analysis.

RESULTS

At post-injury 6-12h, the percentages of PMN and MNC infiltration appeared in injured sites and that of PMN reached peak. At 1 d, the percentage of MNC infiltration appeared and reached peak, while that of PMN decreased. At 3-7 d, the percentage of FBC gradually increased, while that of PMN and MNC decreased. At 10-14d, the percentage of FBC reached peak.

CONCLUSION

The percentages of PMN, MNC and FBC in injured zones showed time-dependent changes, which might be used as reference index for determination of age of skeletal muscle injury.

[Progress in myofibroblast and its application in forensic medicine]

The myofibroblasts have dual characteristics of smooth muscle cells and fibroblasts. In repairing tissular wound, myofibroblasts are involved in fibrogenesis and remodeling the extracellular matrix of the fibrotic cascades reaction. The review describes the morphological characteristics and biological behaviors of myofibroblasts and the application of skin wound age determination, which may provide reference for research in forensic medicine.

Nrf1 is time-dependently expressed and distributed in the distinct cell types after trauma to skeletal muscles in rats

Our goal was to elucidate the dynamic expression and distribution of the nuclear factor erythroid-derived factor 2-related factor 1 (Nrf1) by immunohistochemistry, Western blotting, and real-time PCR during wound healing of contused skeletal muscle in rats. An animal model of skeletal muscle contusion was established in 40 Sprague-Dawley male healthy rats. Samples were taken at 6 h, 12 h, 1 day, 3 days, 5 days, 7 days, 10 days, and 14 days post-injury, respectively (5 rats in each posttraumatic interval). 5 rats were employed as control. A weak immunoreactivity of Nrf1 was observed in the sarcoplasm and nuclei of normal myofibers in control rats. Prominent immunostaining for Nrf1 was seen in a large number of polymorphonuclear cells, round-shaped mononuclear cells and spindle-shaped fibroblastic cells, and regenerated multinucleated myotubes in the injured tissue. Subsequently, neutrophils, macrophages and myofibroblasts were identified as expressing Nrf1 by double immunofluorescent procedures. By real-time PCR analysis, Nrf1 expression was up-regulated and peaked at inflammatory phase. The expression tendency was also confirmed by Western blot. In conclusion, Nrf1 is time-dependently expressed in certain cell types, such as neutrophils, macrophages, myofibroblasts and regenerated multinucleated myotubes, suggesting that Nrf1 may modulate oxidative stress response and regeneration after trauma to skeletal muscles.

[Establishment of skin scald model in mice]

OBJECTIVE

To establish the model of skin scald in mice for the study of skin thermal injuries.

METHODS

After anaesthetization mice were scalded in a 1 cm-diameter circle area on the central dorsum by boiling water at contact times: 10s or 25s. The mice were sacrificed at 1, 3, 5, 7 and 10 days after scald. The skin samples were collected and analyzed by gross and histopathological examinations.

RESULTS

Deep II degree thermal injury involving full-thickness skin was observed in the 10s scald group. III degree thermal injury involving full-thickness skin and the dorsal skeletal muscle was observed in the 25 s scald group.

CONCLUSION

A mouse skin scald model is established which is stable and can be used on the skin thermal injury in future research.

[The number of circulating fibrocytes of skeletal muscle in rats after contusion]

OBJECTION

To investigate the time-dependent appearance of circulating fibrocytes of skeletal muscle in rats after contusion.

METHODS

The model of skeletal muscle wound was established in rat. The circulating fibrocytes in contused skeletal muscle were detected by CD45 and procollagen I double immunofluorescence staining method.

RESULTS

In the control group, CD45- and procollagen I-positive cells were not detected in skeletal muscle. A few CD45 cells were observed aged from 6 h to 1 d after contusion. A few CD45- and procollagen I-positive cells (fibrocytes) initially gathered in injury area 3d after injury. The ratio of positive fibrocytes significantly increased 5 d after injury. The ratio of fibrocytes was highest at 7 d after contusion and then decreased. The volume of fibrocytes showed bigger with injury time increase compared with 3 d group. The expression of procollagen I and CD45 were weakened at 14d after injury.

CONCLUSION

The circulating fibrocytes are detected in contused skeletal muscle in time-dependent pattern. Circulating fibrocytes may be a marker in the wound age determination for contused skeletal muscle.

[The expression of GABA(A) receptor alpha1 and GABA(B) receptor 1 in medulla oblongata solitary nucleus and ambiguous nucleus in the cases of tramadol intoxication]

OBJECTIVE

To observe the expression of GABA(A) receptor alpha1 (GABA(A)alpha1) and GABA(B) receptor 1 (GABA(B)1) in human medulla oblongata solitary nucleus and ambiguous nucleus due to tramadol-induced death.

METHODS

GABA(A)alpha1 and GABA(B)1 were detected by immunohistochemical SP method in tramadol-induced death group and control group. All results were evaluated by images analysis system.

RESULTS

Low expression of GABA(A)alpha1 and GABA(B)1 were detected in solitary nucleus and ambiguous nucleus in the control brain tissue. In cases of tramadol-induced death, the expression of GABA(A)alpha1 and GABA(B)1 significantly increased.

CONCLUSION

The mechanism of tramadol intoxication death could be caused by respiratory depression induced by over-expression of GABA(A)alpha1 and GABA(B)1 in medulla oblongata solitary nucleus and ambiguous nucleus.

[Time-dependent recruitment and differentiation of fibrocytes in mouse skin wound healing]

OBJECTIVE

To investigate the time-dependent recruitment and differentiation of fibrocytes in skin wound healing.

METHODS

Fibrocytes (expressing CD45 and procollagen I ) and myofibroblasts (expressing CD45 and alpha-SMA) were co-localized by immunofluorescent staining. The number of fibrocytes and myofibroblasts was counted at different post-wounding interval.

RESULTS

At 3 d after injury, fibrocytes started to recruit at the margin of the wounds. At 5 d after injury, myofibroblasts started to appear in new formed granulation tissue. The number of fibrocytes and myofibroblasts peaked at 7 d post-wounding.

CONCLUSION

During skin wound healing, myofibroblasts in granulation tissue originated at least partly from fibrocytic differentiation. The time-dependent recruitment and differentiation of fibrocytes may provide new information for wound age determination.

Time-dependent expression and distribution of monoacylglycerol lipase during the skin-incised wound healing in mice

The study investigated the expression of monoacylglycerol lipase (MGL) during the skin-incised wound healing in mice and applicability of the time-dependent expression of MGL to wound age determination by immunofluorescent staining, Western blotting, and real-time PCR. Furthermore, cell types were identified by double immunofluorescence. A total of 45 BALB/c male mice were used in this study. After a 1.5-cm-long incision in the central dorsum skin, mice were killed at intervals ranging from 6 h to 14 days, followed by the sampling of wound margin. In the control, there was a low-level expression of MGL in the epidermis, hair follicles, and glandulae sebaceae. In the injured skin, MGL immunoreactivity was mainly detected in the neutrophils, macrophages, and myofibroblasts. Morphometrically, the average ratios of MGL-positive cells were more than 50% at 5 and 7 days post-wounding, whereas it was <50% at the other posttraumatic intervals. By Western blotting analysis, the average ratio of MGL protein expression was highest at 5 days after injury, which had a ratio of >2.30. Similarly, the relative quantity of MGL mRNA expression maximized at posttraumatic 5 days in comparison with control as detected by real-time PCR, with an average ratio of >2.54. In conclusion, MGL expression is detected in neutrophils, macrophages, and myofibroblasts and significantly up-regulated, suggesting that it may play roles in response to inflammation during skin-incised wound healing. From the viewpoint of forensic pathology, MGL detection is applicable to skin wound age determination.

[Expression of M3 subtype of muscarinic receptor during the skin incised wound healing in mice]

OBJECTIVE

To investigate the expression of M3 subtype of muscarinic receptors (M3R) during the incised wound healing of the skin in mice and the characteristics of its time-dependent.

METHODS

The change of M3R in skin incised wound was detected by immunohistochemical staining and Western blot.

RESULTS

M3R-positive cells were detected in epidermis, hair follicle, sebaceous glands, sweat glands, dermomuscular layer in normal mouse skin. Expression of M3R was mainly detectable in polymorphonuclear cells (PMNs) in the wound specimens aged from 6h to 12h after injury. Afterwards, the M3R-positive cells were mostly mononuclear cells (MNCs) and fibroblastic cells (FBCs) at 1 d to 3d post-injury, whereas the M3R-positive cells were mostly FBCs aged from 5 d to 14d. Morphometrically, the ratio of the M3R-positive cells increased aged from 6h to 12h after injury, with a peak at 12h. The ratios kept a high relatively level aged from 1 d to 5 d, but significantly that lowered as compared with aged 12h after injury. The ratio reached the peak at 7 d again after injury, and then decreased gradually. The M3R protein also revealed a time-dependent tendency with double peaks at 12h and 7 d after injury as detected by Western blotting.

CONCLUSION

M3R is time-dependently expression in PMNs, MNCs and FBCs suggesting that it may play roles during the skin incised wound healing, and M3R may be used as a marker for wound age determination.

[Expression of c-jun during the incised wound healing in mice skin]

OBJECTIVE To investigate the time-dependent expression of c-jun during the healing of incised wound in mice skin.

METHODS

The expression of c-jun in different stages after the incised wound were detected by immunohistochemistry and Western blot.

RESULTS

There was a low level expression of c-jun in normal mice skin. Expression of c-jun was mainly detected in neutrophils from 3 h to 12h after injury. The c-jun positive cells were almost mononuclear cells (MNCs) and fibroblasts between 1 d and 5 d after injury. The c-jun positive cells were mostly fibroblasts between 7 d and 14 d after injury. The ratio of the c-jun positive cells increased in the wound specimens from 3 h to 12 h, peaked at 12 h, declined partially from 1 d to 5 d, and reached the peak secondly at 7 d, then decreased from 10 d to 14 d. The expression of c-jun was observed throughout the wound healing stages by Western blot with two peaks occurring at 12 h and 7 d after injury.

CONCLUSION

The c-jun may play a potential role in inducing apoptosis of neutrophils, MNCs and fibroblasts during skin wound healing, and it may be used as the marker for wound age determination.

Diagnostic aspects for epidemic hemorrhagic fever in legal medical autopsy: report of 2 cases and review

Epidemic hemorrhagic fever (EHF) is known also as hemorrhagic fever with renal syndrome (HFRS). Hantaviruses, a notorious cause of EHF is spreaded by rodents or biting insects, can cause epidemic hemorrhagic fever. This report describes two rare medico-legal autopsy cases died from epidemic hemorrhagic fever. The victims were two male individuals aged 34 years and 29 years. The medico-legal autopsies were requested for alleged medical negligence. In both cases, autopsy reveals lesions to kidneys and lungs with multiple organ hemorrhage and edema, indicative of the generalized capillary damage. On admission to hospital, both patients had the symptom of fever, lumbago, renal failure and recent outdoor activities. The laboratory diagnosis results indicating multiple organ dysfunction syndrome are also important for certificating of EHF. Though the ELISA-based detection of virus-specific IgM antibody which has the highest titers between 8 and 25d after onset of disease is positive in the 34-year-old case and negative in 29-year-old case, the pathological findings and clinical laboratory analysis suggested the both victims died of EHF. In addition, immunohistochemistry analysis for Hantavirus antigen in lung or in tubular cells and PCR having been used increasingly in recent years contribute to the diagnosis of Hantavirus infection.

[Changes of phospho-JNK expression during the skin burned wound healing]

OBJECTIVE

To observe the changes of expression of phosphorylation c-Jun NH2-terminal kinase (p-JNK) during the skin burned wound healing in patients and discuss the molecular mechanism of burned wound healing.

METHODS

The staining intensity and distribution of p-JNK were detected by immunohistochemistry and routine histology in burned skin samples of 12 patients and normal skin samples of 12 control subjects.

RESULTS

In normal skin, the positive signals of p-JNK were mostly localized in basal layer cells of the epidermis, with a positive rate of (8.8+/-1.3)%. In the burned group, the positive signals of p-JNK were mainly localized in the epidermal cells and some inflammatory cells, with a significantly higher positive rate of (31.2+/-3.3)% than the normal group(P<0.01).

CONCLUSION

The changes of p-JNK expression after skin burned might correlate with wound healing.

[Animal model of grading skeletal muscle contusion due to blunt impact in rats]

OBJECTIVE

To establish a new animal model of grading skeletal muscle contusions that could be controllable and repetitive.

METHODS

The rats' gastrocnemius was injured by a new weight-dropping device designed. The force acting on gastrocnemius with a comparatively constant duration and inducing elastic deformation of the gastrocnemius was expressed with velocity (v) and deformation (DF). Instant velocity was changed to create gastrocnemius contusions. Pathological changes of gastrocnemius were graded by the gross and histological examinations of 39 rats.

RESULTS

At low level of impact (v: 2 m/s, DF: 5.5 mm), mild injuries were detected in epimysium and superficial layer of gastrocnemius. At moderate level of impact (v: 2.5 m/s, DF: 6.5 mm), the injuries were observed in epimysium and whole gastrocnemius. At high level of impact (v: 3 m/s, DF: 7.5 mm), severe injuries were seen deeper to soleus with more extensive skeletal muscle damage.

CONCLUSION

Grading of skeletal muscle blunt force contusion is created by parameter of velocity and muscle deformation. The model could be used for further research on skeletal muscle contusions.

[Expressions and time-dependent changes of FAK and phospho-FAK during skin incised wound healing in mouse]

OBJECTIVE

To study the expressions of focal adhesion kinase (FAK) and phospho-FAK( p-FAK) during skin incised wound healing and the applicability of time-dependent expressions of FAK and p-FAK.

METHODS

The expression of FAK and p-FAK in cutaneous incised wound in mouse were investigated by immunohistochmeistry and Western blotting.

RESULTS

FAK and p-FAK expression were detected in polymorphonuclear cells (PMNs) in the wound and adjacent regions 3 hours post-injury. The expressions of FAK and p-FAK were detected in a large number of infiltrating PMNs and some of mononuclear cells (MNCs) from 6 to 24 hours after injury. The MNCs and fibroblastic cells (FBCs) accounted for most part of the FAK and p-FAK positive cells from 3 to 14 days after injury. The numbers of FAK-positive cells increased continuously, reaching a peak at post-injury day 3, and then started to decrease from post-injury day 5 to 14. The changes of p-FAK-positive cells were similar to that of the FAKs, and reached a peak at 12 hours after injury.

CONCLUSION

Both FAK and p-FAK displayed a time-dependent expression during skin incised wound healing in mouse, with p-FAK being superior to FAK. Both FAK and p-FAK may potentially be used as new markers for determination of the wound interval.

[Time-dependent expression of caspase-3 during contused skeletal muscle wound healing in rats]

OBJECTIVE

To investigate the expression of caspase-3 during contused skeletal muscle wound healing in rats and to explore the applicability of caspase-3 in wound age estimation.

METHODS

Male Sprague-Dawley rats undergone anesthesia with 2% pentobarbital sodium (45 mg/kg) were struck by a single strike at the skeletal muscle of the right leg, then were sacrificed by cervical dislocation at different post-traumatic intervals. The changes of caspase-3 activity were assessed by imunohistochemistry, Western blot and caspase-3 colorimetric assay. The skeletal muscle of non-contusion rat's were used as controls.

RESULTS

No caspase-3 was detected in skeletal muscle in the control group. The expression level of caspase-3 in the peripheral area of contused rat skeletal muscle increased gradually and maximized on the fifth day after injury, and then decreased gradually. Caspase-3 was also detected in the regenerated skeletal muscle within 7-14 days after injury.

CONCLUSION

The expression of capase-3 in the peripheral area of contused rat skeletal muscle indicated that it may play a pivotal role in apoptosis of the wounded skeletal muscle and may be used as a marker for wound age estimation. The expression of capase-3 in regenerating skeletal muscle suggests that caspase-3 activity may be used for skeletal muscle differentiation.

[Expression of calpain 1 and calpain 2 during the skin incised wound healing in mice]

OBJECTIVE

To investigate the expressions of calpain1 and calpain2 during the skin incised wound healing in mice.

METHODS

Expression of calpain1 and calpain2 was evaluated by immunohistochemical method.

RESULTS

Both calpain1 and calpain2 were expressed in the skin cells in the control groups. The calpain1 positive cells were remarkably increased and reached the maximal level in day 1 after skin incised wound, decreased after day 3, markedly increased again in day 5, and then gradually decreased from day 7 to 14; the calpain2 positive cells were significantly increased in day 1 and decreased to the minimum in day 3, markedly increased again in day 5, and then gradually decreased from day 7 to 10.

CONCLUSION

The changes of calpain1 and calpain2 expressions appear to be bimodal after incised wound of skin in mice.

Diverse morphological lesions and serious arrhythmias with hemodynamic insults occur in the early myocardial contusion due to blunt impact in dogs

To investigate the morphology and hemodynamics of the early myocardial contusion, an animal model of cardiac contusion was established by impact to the precordial region at sternum at velocity of 10.0m/s with a mechanical elastic-cord propelled impactor in 19 dogs. The electrocardiogram and both the left and right intra-ventricular pressures were recorded continuously throughout the experiment. Histological and immunohistochemical examinations of myoglobin, creatine kinase-MB and fibrinogen were conducted. At the moment of impact, abrupt over-pressures within the left and right ventricles occurred with concomitant serious arrhythmias followed by variety of cardiac conduction disorders and depressed left and right ventricular systolic pressures during the observation times. Histologically, lesions of myocardial contusions were identified at subepicardial, myocardial or subendocardial layer as interstitial hemorrhage, disruption or coagulative necrosis as well as contraction band necrosis of the muscle fibers, which might be categorized into the hemorrhagic, necrotized and mixed forms. The three forms of lesions were found to exist independently, or co-existed in a heart. However, severity of the lesions varied greatly with different parts even within a heart. Intravascular thromboses were occasionally discovered post-impact. Immunohistochemically, loss of myoglobin and creatine kinase-MB from cardiac cells, and accumulation of fibrinogen at the cell membranes were detected 5min post-impact. The intracellular accumulation of fibrinogen increased with extension of post-impact intervals. Our results indicate that diverse morphological lesions concomitant with hemodynamic compromise and serious, even fatal arrhythmias occur in the early myocardial contusion, and intravascular thromboses are occasionally produced, suggesting that traumatic myocardial ischemic lesion may be induced due to blunt impact to the precordial region.