Expression of metabotropic glutamate receptor 1a in a rat cortical neuronal model of in vitro mechanical injury and the effects of its competitive antagonist (RS)-1-aminoindan-1,5-dicarboxylic acid

The present study established a rat cortical neuronal model of in vitro mechanical injury. At 30 minutes after injury, the survival rate of the injured cortical neurons was decreased compared with normal neurons, and was gradually decreased with aggravated degree of injury. Reverse transcription-polymerase chain reaction results showed that at 1 hour after injury, there was increased expression of metabotropic glutamate receptor la in cortical neurons. Immunohistochemical staining results showed that at 30 minutes after injury, the number of metabotropic glutamate receptor 1a-positive cells increased compared with normal neurons. At 12 hours after injury, lactate dehydrogenase activity in the （RS）-l-aminoindan-1, 5-dicarboxylic acid （AIDA）-treated injury neurons was si[jnificantly decreased than that in the pure injury group. At 1 hour after injury, intracellular free Ca＂＋ concentration was markedly decreased in the AIDA-treated injury neurons than that in the pure injury neurons. These findings suggest that after mechanical injury to cortical neurons, metabotropic glutamate receptor la expression increased. The resulting increase in intracellular free Ca2＋ concentration was blocked by AIDA, indicating that AIDA exhibits neuroprotective effects after mechanical injury.

Edaravone promotes functional recovery after mechanical peripheral nerve injury

Edaravone has been shown to reduce ischemia/reperfusion-induced peripheral nerve injury. However, the therapeutic effect of edaravone on peripheral nerve injury caused by mechanical factors is unknown. In the present study, we established a peripheral nerve injury model by crushing the sciatic nerve using hemostatic forceps, and then administered edaravone 3 mg/kg intraperitoneally. The sciatic functional index and superoxide dismutase activity of the sciatic nerve were increased, and the malondialdehyde level was decreased in animals in the edaravone group compared with those in the model group. Bcl-2 expression was increased, but Bax expres- sion was decreased in anterior horn cells of the L4-6 spinal cord segments. These results indicated that edaravone has a neuroprotective effect following peripheral nerve injury caused by mechan- ical factors through alleviating free radical damage to cells and inhibiting lipid peroxidation, as well as regulating apoptosis-related protein expression.

SIRT1 Protects Cortical Neurons from Shear Stress Induced Mechanical Injury

Emerging evidence implicates that SIRT1,one of NAD-dependent protein deacetylase,is involved in the regulation of neuronal survival.However,the role of SIRT1 in mechanical injury is still unclear.Here,we first established a mechanical injury model of rat cortical neurons through exposing to 10 dyn/cm 2 laminar shear stress for 4 h.At the same time,we found that SIRT1 expression increased during the process of shear stress induced neuronal injury.SIRT1 overexpression in cortical neurons significantly decreased the percentage of died cells induced by shear stress.Our results demonstrate that SIRT1 may play potential neuroprotective effects in shear stress induced mechanical injury.

Identification of injury type using somatosensory and motor evoked potentials in a rat spinal cord injury model

The spinal cord is at risk of injury during spinal surgery.If intraoperative spinal co rd injury is identified early,irreve rsible impairment or loss of neurological function can be prevented.Different types of spinal cord injury result in damage to diffe rent spinal cord regions,which may cause diffe rent somatosensory and motor evoked potential signal res ponses.In this study,we examined electrophysiological and histopathological changes between contusion,distra ction,and dislocation spinal cord injuries in a rat model.We found that contusion led to the most severe dorsal white matter injury and caused considerable attenuation of both somatosensory and motor evoked potentials.Dislocation resulted in loss of myelinated axons in the lateral region of the injured spinal cord along the rostrocaudal axis.The amplitude of attenuation in motor evoked potential responses caused by dislocation was greater than that caused by contusion.After distraction injury,extracellular spaces were slightly but not significantly enlarged;somatosensory evoked potential res ponses slightly decreased and motor evoked potential responses were lost.Correlation analysis showed that histological and electrophysiological findings we re significantly correlated and related to injury type.Intraope rative monitoring of both somatosensory and motor evoked potentials has the potential to identify iatrogenic spinal cord injury type during surgery.

The deterministic condition for the ground reaction force acting point on the combined knee valgus and tibial internal rotation moments in early phase of cutting maneuvers in female athletes

Background:Combined knee valgus and tibial internal rotation(VL+IR)moments have been shown to stress the anterior cruciate ligament(ACL)in several in vitro cadaveric studies.To utilize this knowledge for non-contact ACL injury prevention in sports,it is necessary to elucidate how the ground reaction force(GRF)acting point(center of pressure(CoP))in the stance foot produces combined knee VL+IR moments in risky maneuvers,such as cuttings.However,the effects of the GRF acting point on the development of the combined knee VL+IR moment in cutting are still unknown.Methods:We first established the deterministic mechanical condition that the CoP position relative to the tibial rotational axis differentiates the GRF vector’s directional probability for developing the combined knee VL+IR moment,and theoretically predicted that when the CoP is posterior to the tibial rotational axis,the GRF vector is more likely to produce the combined knee VL+IR moment than when the CoP is anterior to the tibial rotational axis.Then,we tested a stochastic aspect of our theory in a lab-controlled in vivo experiment.Fourteen females performed 60˚cutting under forefoot/rearfoot strike conditions(10 trials each).The positions of lower limb markers and GRF data were measured,and the knee moment due to GRF vector was calculated.The trials were divided into anterior-and posterior-CoP groups depending on the CoP position relative to the tibial rotational axis at each 10 ms interval from 0 to 100 ms after foot strike,and the occurrence rate of the combined knee VL+IR moment was compared between trial groups.Results:The posterior-CoP group showed significantly higher occurrence rates of the combined knee VL+IR moment(maximum of 82.8%)at every time point than those of the anterior-CoP trials,as theoretically predicted by the deterministic mechanical condition.Conclusion:The rearfoot strikes inducing the posterior CoP should be avoided to reduce the risk of non-contact ACL injury associated with the combined knee VL+IR stress.

Puerarin ameliorates allodynia and hyperalgesia in rats with peripheral nerve injury

Puerarin is a major active ingredient of the traditional Chinese plant medicine,Radix Puerariae,and commonly used in the treatment of myocardial and cerebral ischemia.However,the effects of puerarin on neuropathic pain are still unclear.In this study,a neuropathic pain animal model was created by partial sciatic nerve ligation.Puerarin（30 or 60 mg/kg） was intraperitoneally injected once a day for 7 days.Mechanical allodynia and thermal hyperalgesia were examined at 1 day after model establishment.Mechanical threshold and paw withdrawal latency markedly increased in a dose-dependent manner in puerarin-treated rats,especially at 7 days after model establishment.At 7 days after model establishment,quantitative real-time reverse transcriptase-polymerase chain reaction results showed that puerarin administration reversed m RNA expression of transient receptor potential vanilloid 1（Trpv1） and transient receptor potential ankyrin 1（Trpa1） in a dose-dependent manner in dorsal root ganglion neurons after peripheral nerve injury.These results suggest that puerarin dose-dependently ameliorates neuropathic pain by suppressing Trpv1 and Trpa1 up-regulation in dorsal root ganglion of neuropathic pain rats.

An analytical poroelastic model for laboratorial mechanical testing of the articular cartilage (AC)

The articular cartilage （AC） can be seen as a biphasic poroelastic material. The cartilage deformation under compression mainly leads to an interstitial fluid flow in the porous solid phase. In this paper, an analytical poroelastic model for the AC under laboratorial mechanical testing is developed. The solutions of interstitial fluid pressure and velocity are obtained. The results show the following facts. （i） Both the pressure and fluid velocity amplitudes are proportional to the strain loading amplitude. （ii） Both the amplitudes of pore fluid pressure and velocity in the AC depend more on the loading amplitude than on the frequency. Thus, in order to obtain the considerable fluid stimulus for the AC cell responses, the most effective way is to increase the loading amplitude rather than the frequency. （iii） Both the interstitiM fluid pressure and velocity are strongly affected by permeability variations. This model can be used in experimental tests of the parameters of AC or other poroelastic materials, and in research of mechanotransduction and injury mechanism involved interstitial fluid flow.

The Mechanism of Acute Lung Injury Induced by Nickel Carbonyl in Rats

Nickel carbonyl is a highly toxic metal compound produced from the reaction that occurs between nickel and carbon monoxide under pressure. As previously reported, nickel carbonyl can cause acute aspiration pneumonia, and animal experiments showed it was toxic to animal lung, liver, brain, and other vital organs[1]. However, few studies have investigated nickel carbonyl poisoning in humans.

Differential Proteomics Reveals the Potential Injury Mechanism Induced by Heavy Ion Radiation in Mice Ovaries

In the present study, we used a proteomics approach based on a two-dimensional electrophoresis （2-DE） reference map to investigate protein expression in the ovarian tissues of pubertal Swiss-Webster mice subjected to carbon ion radiation （CIR）. Among the identified proteins, ubiquitin carboxy-terminal hydrolase L1 （UCH-L1） is associated with the cell cycle[1] and that it influences proliferation in ovarian tissues. We analyzed the expression of UCH-L1 and the proliferation marker proliferation cell nuclear antigen （PCNA） following CIR using immunoblotting and immunofluorescence. The proteomics and biochemical results provide insight into the underlying mechanisms of CIR toxicity in ovarian tissues.

“Standby” EMT and “immune cell trapping” structure as novel mechanisms for limiting neuronal damage after CNS injury

The central nervous system （CNS） contains the two most important organs, the brain and spinal cord, for the orchestration of the mental and physical activities of life. Because of its importance, the human body has evolved barrier systems to protect CNS tissue from the external environment. This barrier is a membrane composed of tightly apposed cells and is selectively permeable to specific molecules by way of membrane transporters.

Mechanical Eye Trauma Epidemiology, Prognostic Factors, and Management Controversies—An Update

Purpose of Review: The management of eye injuries is both difficult and argumentative. This study attempts to highlight the management of ocular trauma using currently available information in the literature and author experience. This review presents a workable framework from the first presentation, epidemiology, classification, investigations, management principles, complications, prognostic factors, final visual outcome and management debates. Review Findings: Mechanical ocular trauma is a leading cause of monocular blindness and possible handicap worldwide. Among several classification systems, the most widely accepted is Birmingham Eye Trauma Terminology (BETT). Mechanical ocular trauma is a topic of unsolved controversy. Patching for corneal abrasion, paracentesis for hyphema, the timing of cataract surgery and intraocular lens implantation are all issues in anterior segment injuries. Regarding posterior segment controversies, the timing of vitrectomy, use of prophylactic cryotherapy, the necessity of intravitreal antibiotics in the absence of infection, the use of vitrectomy vs vitreous tap in traumatic endophthalmitis is the issues. The pediatric age group needs to be approached by a different protocol due to the risk of amblyopia, intraocular inflammation, and significant vitreoretinal adhesions. The various prognostic factors have a role in the final visual outcome. B scan is used to exclude R.D, Intraocular foreign body (IOFB), and vitreous haemorrhage in hazy media. Individual surgical strategies are used for every patient according to the classification and extent of the injuries. Conclusion: This article examines relevant evidence on the management challenges and controversies of mechanical trauma of the eye and offers treatment recommendations based on published research and the authors’ own experience.

Parametric analysis of craniocerebral injury mechanism in pedestrian trafficaccidents based on finite element methods

Purpose:The toughest challenge in pedestrian traffic accident identification lies in ascertaining injurymanners.This study aimed to systematically simulate and parameterize 3 types of craniocerebral injuryincluding impact injury,fall injury,and run-over injury,to compare the injury response outcomes ofdifferent injury manners.Methods:Based on the total human model for safety(THUMS)and its enhanced human model THUMShollow structures,a total of 84 simulations with 3 injury manners,different loading directions,andloading velocities were conducted.Von Mises stress,intracranial pressure,maximum principal strain,cumulative strain damage measure,shear stress,and cranial strain were employed to analyze the injuryresponse of all areas of the brain.To examine the association between injury conditions and injuryconsequences,correlation analysis,principal component analysis,linear regression,and stepwise linearregression were utilized.Results:There is a significant correlation observed between each criterion of skull and brain injury(p<0.01 in all Pearson correlation analysis results).A 2-phase increase of cranio-cerebral stress andstrain as impact speed increases.In high-speed impact(>40 km/h),the Von Mises stress on the skull waswith a high possibility exceed the threshold for skull fracture(100 MPa).When falling and makingtemporal and occipital contact with the ground,the opposite side of the impacted area experienceshigher frequency stress concentration than contact at other conditions.Run-over injuries tend to have amore comprehensive craniocerebral injury,with greater overall deformation due to more adequate kinetic energy conduction.The mean value of maximum principal strain of brain and Von Mises stress ofcranium at run-over condition are 1.39 and 403.8 MPa,while they were 1.31,94.11 MPa and 0.64,120.5 MPa for the impact and fall conditions,respectively.The impact velocity also plays a significant rolein craniocerebral injury in impact and fall loading conditions(the p of all F-test<0.05).A regressionequation of the craniocerebral injury manners in pedestrian accidents was established.Conclusion:The study distinguished the craniocerebral injuries caused in different manners,elucidatedthe biomechanical mechanisms of craniocerebral injury,and provided a biomechanical foundation forthe identification of craniocerebral injury in legal contexts.

Influence of muscle activation on lumbar injury under a specific+Gz load

Purpose:The present study aimed to analyze the influence of muscle activation on lumbar injury under aspecific+Gz load.Methods:A hybrid finite element human body model with detailed lumbar anatomy and lumbar muscleactivation capabilities was developed.Using the specific+Gz loading acceleration as input,the kinematicand biomechanical responses of the occupant's lower back were studied for both activated and deactivated states of the lumbar muscles.Results:The results indicated that activating the major lumbar muscles enhanced the stability of theoccupant's torso,which delayed the contact between the occupant's head and the headrest.Lumbarmuscle activation led to higher strain and stress output in the lumbar spine under+Gz load,such as themaximum Von Mises stress of the vertebrae and intervertebral discs increased by 177.9%and 161.8%,respectively,and the damage response index increased by 84.5%.Conclusion:In both simulations,the occupant's risk of lumbar injury does not exceed 10%probability.Therefore,the activation of muscles could provide good protection for maintaining the lumbar spine andreduce the effect of acceleration in vehicle travel direction.

Effects of flexibility and strength training on peak hamstring musculotendinous strains during sprinting

Background:Hamstring injury is one of the most common injuries in sports involving sprinting.Hamstring flexibility and strength are often considered to be modifiable risk factors in hamstring injury.Understanding the effects of hamstring flexibility or strength training on the biomechanics of the hamstring muscles during sprinting could assist in improving prevention strategies and rehabilitation related to these injuries.The purpose of this study was to determine the effects of altering hamstring flexibility or strength on peak hamstring musculotendinous strain during sprinting.Methods:A total of 20 male college students(aged 18-24 years)participated and were randomly assigned to either a flexibility intervention group or a strength intervention group.Each participant executed exercise training 3 times a week for 8 weeks.Flexibility,sprinting,and isokinetic strength testing were performed before and after the 2 interventions.Paired t tests were performed to determine hamstring flexibility or strength intervention effects on optimal hamstring musculotendinous lengths and peak hamstring musculotendinous strains during sprinting.Results:Participants in the flexibility intervention group significantly increased the optimal musculotendinous lengths of the semimembranosus and biceps long head(p<0.026)and decreased peak musculotendinous strains in all 3 bi-articulate hamstring muscles(p<0.004).Participants in the strength-intervention group significantly increased the optimal musculotendinous lengths of all 3 hamstring muscles(p<0.041)and significantly decreased their peak musculotendinous strain during sprinting(p<0.017).Conclusion:Increasing hamstring flexibility or strength through exercise training may assist in reducing the risk of hamstring injury during sprinting for recreational male athletes.

Light-emitting-diode induced retinal damage and its wavelength dependency in vivo

AIM： To examine light-emitting-diode（LED）-induced retinal neuronal cell damage and its wavelength-driven pathogenic mechanisms.METHODS： Sprague-Dawley rats were exposed to blue LEDs（460 nm）,green LEDs（530 nm）,and red LEDs（620 nm）.Electroretinography（ERG）,Hematoxylin and eosin（H＆E） staining,transmission electron microscopy（TEM）,terminal deoxynucleotidyl transferase d UTP nick end labeling（TUNEL）,and immunohistochemical（IHC） staining,Western blotting（WB） and the detection of superoxide anion（O2^-·）,hydrogen peroxide（H2O2）,total iron,and ferric（Fe^3＋） levels were applied.RESULTS： ERG results showed the blue LED group induced more functional damage than that of green or red LED groups.H＆E staining,TUNEL,IHC,and TEM revealed apoptosis and necrosis of photoreceptors and RPE,which indicated blue LED also induced more photochemical injury.Free radical production and iron-related molecular marker expressions demonstrated that oxidative stress and ironoverload were associated with retinal injury.WB assays correspondingly showed that defense gene expression was up-regulated after the LED light exposure with a wavelength dependency.CONCLUSION： The study results indicate that LED bluelight exposure poses a great risk of retinal injury in awake,task-oriented rod-dominant animals.The wavelengthdependent effect should be considered carefully when switching to LED lighting applications.

Detailed description of Division I ice hockey concussions:Findings from the NCAA and Department of Defense CARE Consortium

Objective:Since concussion is the most common injury in ice hockey,the objective of the current study was to elucidate risk factors,specific mechanisms,and clinical presentations of concussion in men’s and women’s ice hockey.Methods:Ice hockey players from 5 institutions participating in the Concussion Assessment,Research,and Education Consortium were eligible for the current study.Participants who sustained a concussion outside of this sport were excluded.There were 332(250 males,82 females)athletes who participated in ice hockey,and 47(36 males,11 females)who sustained a concussion.Results:Previous concussion(odds ratio(OR)=2.00;95%confidence interval(95%CI):1.02‒3.91)was associated with increased incident concussion odds,while wearing a mouthguard was protective against incident concussion(OR=0.43;95%CI:0.22‒0.85).Overall,concussion mechanisms did not significantly differ between sexes.There were specific differences in how concussions presented clinically across male and female ice hockey players,however.Females(9.09%)were less likely than males(41.67%)to have a delayed symptom onset(p=0.045).Additionally,females took significantly longer to reach asymptomatic(p=0.015)and return-to-play clearance(p=0.005).Within the first 2 weeks post-concussion,86.11%of males reached asymptomatic,while only 45.50%of females reached the same phase of recovery.Most males(91.67%)were cleared for return to play within 3 weeks of their concussion,compared to less than half(45.50%)of females.Conclusion:The current study proposes possible risk factors,mechanisms,and clinical profiles to be validated in future concussions studies with larger female sample sizes.Understanding specific risk factors,concussion mechanisms,and clinical profiles of concussion in collegiate ice hockey may generate ideas for future concussion prevention or intervention studies.

Effects of mechanical operation-induced root injury on maize growth and yield

A 2-year field experiment was conducted in 2015 and 2016 by using artificial root pruning to simulate mechanical root injury caused by agricultural machinery components and reveal its effects on maize growth and yield.Quasi-level orthogonal experimental design was employed to create orthogonal tables with four factors of interest,namely,pruning time(jointing stage,JS;big trumpet period,BTP),pruning method(unilateral pruning,UNP;bilateral pruning,BIP),pruning distance(5,10,and 15 cm)and pruning depth(5,10,and 15 cm).Results revealed that (1)maize growth was inhibited at the beginning of root pruning;(2)stem diameter(SD)and plant height(PHE)were smaller than those of the control check(CK)but exceeded the latter after 20 d of root pruning in JS;(3)SD and PHE were always smaller than those of the CK under root pruning in BTP;(4)T8(BTP,BIP,5 cm of pruning distance and 15 cm of pruning depth)can reach to a significant level(p<0.01).The vertical distribution and total dry weight(TDW)of maize roots in soil were affected by different root pruning treatments.When pruning in JS,the root ratio in 0-10 cm soil was 11.6%in T2(JS,UNP,a pruning distance of 10 cm and pruning depth of 10 cm).When pruning in BTP,the root ratio of 10-20 cm soil layer increased by 15%.However,the TDW of maize decreased,the largest of which occurred in T8 at 53%.With the exception of a 0.43%increase in T3(JS,UNP,15 cm of pruning distance and 15 cm of pruning depth),the maize yield of all other treatments decreased compared with that of CK,and the largest reduction was in T8 at up to 19.1%.This finding suggests that a small pruning distance and a large pruning depth greatly influence the growth and yield of maize before and during pruning in BTP.The influence of BIP is greater than that of UNP.These results provide evidence for the effects of mechanical root injury on maize growth and yield and serve as a reference for the selection of mechanical topdressing parameters.

“When you’re down, stay down”:A lesson for all competitive alpine skiers supported by an ACL rupture measured in vivo

Background:During an experiment,a ski racer equipped with various measurement devices suffered an anterior cruciate ligament(ACL)rupture in his right knee.The aim of this study was to describe the underlying injury mechanism from a functional perspective.Methods:Eight giant slalom turns(i.e.,4 left turns),followed by 1 left turn at which the ACL injury occurred,were recorded by 2 video cameras,electromyography of 4 relevant muscle groups,inertial measurement units to measure knee and hip angles,and pressure insoles to determine ground reaction forces.Results:Due to a loss of balance,the ski racer began to slide sideways at the apex of a left turn.During sliding,his right(outside)leg was actively abducted upward without touching the ground.The ski racer then attempted to stand up again by dropping his leg back towards the snow surface.The end of this dropping was accompanied by a decrease in electromyographic activity in the knee stabilizing muscles.Once the inside edge of the outer ski caught the snow surface,a rapidly increasing peak force,knee flexion,and an aggressive sudden activation of the vastus medialis muscle were observed,while biceps femoris and rectus femoris further decreased their activation levels.This likely resulted in excessive anterior translation of the tibia relative to the femur,causing damage to the ACL.Conclusion:Our example emphasizes that ski racers should not get up until they stop sliding.Remember:“When you’re down,stay down.”

Achilles Tendon Rupture with Isolated Medial Malleolar Fracture in Ipsilateral Ankle:A Case Report

Achilles tendon ruptures and malleol fractures are commonly seen injuries in orthopaedic and traumatology practice, but what is rare is their concomitant. In this report, we aimed to present a rare case of a patient who has isolated medial malleolar fracture and achilles tendon rupture in ipsilateral ankle after an ankle sprain due to a fall from stairs and mechanism of injury.

Experimental study of acute lung injury induced by different tidal volume ventilation in rats

Mechanical ventilation (MV) is a dual blade sward which if misused could lead to lung injury, called ventilator induced lung injury (VILI). Pathogenesis of VILI is very complex with various manifestations, which is the focus in MV field in recent years. 1 In our research, the rats were ventilated with different tidal volume, then the pathological changes of the lungs were observed under macroscopy, light and electronic microscope, and various laboratory tests in blood and bronchoalveolar lavage fluid (BALF) were also carried out in order to probe further the pathologic characteristics and the pathogenesis of VILI.