Objective To study the characteristics of the sciatic nerve injuries inflicted by highvelocity triangle fragments in swine.Methods According to the injury position,14 swines weighing (34.29±5.2)kg were divided into two groups.All swines were shot by 0.37 g triangle fragments at (773.1±12.4)m/s aimed at the midpoint of the lateral body surface projection of the right sciatic nerve in Group A(n=7)and at 2 cm aside from sciatic nerve in Group B(n=7).The entrance,exit and length of wound tract,distance between nerve and wound tract were detected,and the pathology of sciatic nerve and wound tract at 48 hours after injury were observed under light microscope and electron microscope.Results The course of the fragments was deviated to different extent.Six sciatic nerves were in primary wound tract,four of which were lacerated and ruptured at different degrees.The light microscope showed pathological changes including severe hemorrhage and edema,leukocytic infiltration,neurotmesis,axonotmesis and light myelin coloration;while electron microscope showed severe degeneration of myelin sheath and neuraxon distortion.Six nerves(one in Group A and five in Group B)were in the concussion zone,with the distance between sciatic nerve and primary wound tract for(2.07±0.45)cm.Hyporrhea and hyperemia under perilemma and perineurium,partial nerve fiber disrupt and axonotmesis were observed by light microscope and partly myelin sheath delamination by electron microscope.Two nerves (one in Group A and another in Group B)were in the contusion zone,with moderate pathological changes.Conclusions The track of high velocity triangle fragments is unstable in the tissues.High disrupt rate,severe and wide extent lesion,early Wallerian degeneration are the main characteristics of direct injuries of swine's sciatic nerves.Indirect injuries can induce pathologic changes too,for which the lesion severity is related to the distance between nerves and primary wound tract.

Objective To assess the effects of repeated mild traumatic brain injury(rmTBI)in the parietal cortex on neuronal morphology and synaptic plasticity in the medulla oblongata of mice.Methods Thirty-two male ICR mice were randomly divided into sham operation group(n=8)and rmTBI group(n=24).The mice in the latter group were subjected to repeated mild impact injury of the parietal cortex by a free-falling object.The mice surviving the injuries were evaluated for neurological deficits using neurological severity scores(NSS),righting reflex test and forced swimming test,and pathological changes of the neuronal cells in the medulla oblongata were observed with HE and Nissl staining.Western blotting and immunofluorescence staining were used to detect the expressions of neuroligin 1(NLG-1)and postsynaptic density protein 95(PSD-95)in the medulla oblongata of the mice that either survived rmTBI or not.Results None of the mice in the sham-operated group died,while the mortality rate was 41.67%in rmTBI group.The mice surviving rmTBI showed significantly reduced NSS,delayed recovery of righting reflex,increased immobility time in forced swimming test(P<0.05),and loss of Nissl bodies;swelling and necrosis were observed in a large number of neurons in the medulla oblongata,where the expression levels of NLG-1 and PSD-95 were significantly downregulated(P<0.05).The mice that did not survive rmTBI showed distorted and swelling nerve fibers and decreased density of neurons in the medulla oblongina with lowered expression levels of NLG-1 and PSD-95 compared with the mice surviving the injuries(P<0.01).Conclusion The structural and functional anomalies of the synapses in the medulla oblongata may contribute to death and neurological impairment following rmTBI in mice.

Objective To assess the effects of repeated mild traumatic brain injury(rmTBI)in the parietal cortex on neuronal morphology and synaptic plasticity in the medulla oblongata of mice.Methods Thirty-two male ICR mice were randomly divided into sham operation group(n=8)and rmTBI group(n=24).The mice in the latter group were subjected to repeated mild impact injury of the parietal cortex by a free-falling object.The mice surviving the injuries were evaluated for neurological deficits using neurological severity scores(NSS),righting reflex test and forced swimming test,and pathological changes of the neuronal cells in the medulla oblongata were observed with HE and Nissl staining.Western blotting and immunofluorescence staining were used to detect the expressions of neuroligin 1(NLG-1)and postsynaptic density protein 95(PSD-95)in the medulla oblongata of the mice that either survived rmTBI or not.Results None of the mice in the sham-operated group died,while the mortality rate was 41.67%in rmTBI group.The mice surviving rmTBI showed significantly reduced NSS,delayed recovery of righting reflex,increased immobility time in forced swimming test(P<0.05),and loss of Nissl bodies;swelling and necrosis were observed in a large number of neurons in the medulla oblongata,where the expression levels of NLG-1 and PSD-95 were significantly downregulated(P<0.05).The mice that did not survive rmTBI showed distorted and swelling nerve fibers and decreased density of neurons in the medulla oblongina with lowered expression levels of NLG-1 and PSD-95 compared with the mice surviving the injuries(P<0.01).Conclusion The structural and functional anomalies of the synapses in the medulla oblongata may contribute to death and neurological impairment following rmTBI in mice.