Expressions of TGF-β1 and EⅢA-FN after Rat Skeletal Muscle Contusion and Wound Age Estimation / 法医学杂志

Objective To study the expressions of transforming growth factor-β1 （TGF-β1） and EⅢA-fibronectin （EⅢA-FN） at different time points of antemortem injury, antemortem injury postmortem expression and postmortem injury and to explore their application value in wound age estimation. Methods A model of rat skeletal muscle contusion was established. The rats were randomly divided into normal control group （n=5）, antemortem contusion group （n=40）, antemortem contusion postmortem expression group （n=110） and postmortem injury group （n=25）. The expressions of TGF-β1 and EⅢA-FN after rat skeletal muscles antemortem contusion were detected with immunohistochemical staining. Expression changes of TGF-β1 and EⅢA-FN mRNA in each group were analyzed with real-time fluorescence quantitative PCR. Results Immunohistochemical staining results showed that a large number of polymorphonuclear leukocyte, mononuclear cells and fibroblastic cells showed a strong expression of TGF-β1 in wounded zones 12 h-14 d after antemortem contusion. EⅢA-FN was mainly distributed in the extracellular matrix, 3 to 7 d post-traumatic. Real-time fluorescence quantitative PCR results showed that TGF-β1 and EⅢA-FN mRNA in antemortem injury group reached the peak at 3 and 5 d post-traumatic respectively. The expressions of TGF-β1 and EⅢA-FN mRNA in antemortem contusion postmortem expression group peaked at 6 h and 12 h postmortem. The expression of TGF-β1 and EⅢA-FN mRNA in postmortem injury group 0.5-12 h postmortem was significantly lower than those of the normal control group and the antemortem contusion group. Conclusion TGF-β1 and EⅢA-FN might become a reference index for skeletal muscle wound age estimation.

Research Advances in Sympathetic Remodeling after Myocardial Infarction and Its Significance in Forensic Science / 法医学杂志

Sympathetic remodeling after myocardial infarction is presented as denervation, sympathetic nerve sprouting and sympathetic hyperinnervation, and is closely related to ventricular tachyarrhythmias and even sudden cardiac death at convalescence in patients with myocardial infarction. This article reviews the anatomic structure, morphology and functional remodeling of cardiac sympathetic nerve, as well as its role in healed myocardial infarction identification, which may provide references for forensic research.

Comparison of the Skin and Skeletal Muscle Contusion in Rats Induced by Blunt Force with Different Heights / 法医学杂志

OBJECTIVES@#To explore the differences in the repair process of skin and skeletal muscle after contusion caused by blunt force attack with different heights.@*METHODS@#Three degrees of contusion were performed on SD rats' right hind limbs by a designed free-dropping device falling from 15, 30 and 50 cm heights, which as a main consideration factor for degree of injury. The repair process of skin and skeletal muscle at 6 h, 24 h, 3 d, 7 d and 13 d after contusion were observed using routine histological methods.@*RESULTS@#Hematoma within skin and/or muscle was found in the rats' hind limbs after contusion with three different heights. The repair processes were similar at 24 h after contusion. However, with the increase of height, the display degree was more obvious. At 3 d after contusion, the RBC of the hemorrhagic region would be decomposed and elapsed in 15 cm contusion group, but for 30 cm contusion group, it delayed to 7 d. At 13 d after contusion, the similar result was found in 15 cm and 30 cm contusion groups, in contrast, the 50 cm contusion group was still in the proliferative phase.@*CONCLUSIONS@#With the increase of height, the occurring rate of hematoma within skin and muscle at the same time increases, and the more serious histological appearance after contusion, including inflammation and proliferation, the longer healing process are observed. According to the results of present study and considering forensic application, the contusion model with 50 cm height （2.58 J/cm²） is recommended as the experimental animal model for the future study of wound age estimation on contusion.

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

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 / 法医学杂志

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 / 法医学杂志

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.

The number of circulating fibrocytes of skeletal muscle in rats after contusion / 法医学杂志

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.

Time-dependent recruitment and differentiation of fibrocytes in mouse skin wound healing / 法医学杂志

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.

Expression of M3 subtype of muscarinic receptor during the skin incised wound healing in mice / 法医学杂志

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 / 法医学杂志

UNLABELLED@#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.

The time-dependent changes of phospho-JNK expression during the skin incised wound healing in mice / 法医学杂志

OBJECTIVE@#To investigate the changes of phospho-JNK (p-JNK) during the incised wound healing of the skin in mice and to explore the rule of the time-dependent change of p-JNK in wound age determination.@*METHODS@#The changes of p-JNK expression in incised skin wound were detected by immunohistochemistry and Western blot.@*RESULTS@#There was a minimal baseline staining of p-JNK in control mouse skin. Changes of p-JNK expression were mainly detectable in neutrophils in the wound specimens from 3 hours to 12 hours after injury. Afterwards, the p-JNK positive cells were mostly mononuclear cells and fibroblasts between post-injury day 1 and day 5, whereas the p-JNK positive cells were mostly fibroblasts between post-injury day 7 and day 14. Morphometrically, the ratio of the p-JNK positive cells to the total increased gradually in the wound specimens from 3 hours to day 1, and maximized at day 1 with a slight decrease from post-injury day 3 to day 5. The ratio showed a second peak in the specimens of day 7, and then decreased gradually from post-injury day 10 to day 14. The changes of p-JNK expression were observed throughout the wound healing stages by Western blot as well, with a peak expression occurring between 12 hour and day 3 after injury.@*CONCLUSION@#p-JNK may play a pivotal role in inducing apoptosis of neutrophils, mononuclear cells, and fibroblasts during skin wound healing and meanwhile, p-JNK may be a potentially useful marker for wound age determination.

Animal model of grading skeletal muscle contusion due to blunt impact in rats / 法医学杂志

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.