Exploring the role of Prx II in mitigating endoplasmic reticulum stress and mitochondrial dysfunction in neurodegeneration.

BACKGROUND: Neurodegenerative diseases are increasingly recognized for their association with oxidative stress, which leads to progressive dysfunction and loss of neurons, manifesting in cognitive and motor impairments. This study aimed to elucidate the neuroprotective role of peroxiredoxin II (Prx II) in counteracting oxidative stress-induced mitochondrial damage, a key pathological feature of neurodegeneration. METHODS: We investigated the impact of Prx II deficiency on endoplasmic reticulum stress and mitochondrial dysfunction using HT22 cell models with knocked down and overexpressed Prx II. We observed alcohol-treated HT22 cells using transmission electron microscopy and monitored changes in the length of mitochondria-associated endoplasmic reticulum membranes and their contact with endoplasmic reticulum mitochondria contact sites (EMCSs). Additionally, RNA sequencing and bioinformatic analysis were conducted to identify the role of Prx II in regulating mitochondrial transport and the formation of EMCSs. RESULTS: Our results indicated that Prx II preserves mitochondrial integrity by facilitating the formation of EMCSs, which are essential for maintaining mitochondrial Ca2+ homeostasis and preventing mitochondria-dependent apoptosis. Further, we identified a novel regulatory axis involving Prx II, the transcription factor ATF3, and miR-181b-5p, which collectively modulate the expression of Armcx3, a protein implicated in mitochondrial transport. Our findings underscore the significance of Prx II in protecting neuronal cells from alcohol-induced oxidative damage and suggest that modulating the Prx II-ATF3-miR-181b-5p pathway may offer a promising therapeutic strategy against neurodegenerative diseases. CONCLUSIONS: This study not only expands our understanding of the cytoprotective mechanisms of Prx II but also offers necessary data for developing targeted interventions to bolster mitochondrial resilience in neurodegenerative conditions.

Investigating neuropathological changes and underlying neurobiological mechanisms in the early stages of primary blast-induced traumatic brain injury: Insights from a rat model.

The utilization of explosives and chemicals has resulted in a rise in blast-induced traumatic brain injury (bTBI) in recent times. However, there is a dearth of diagnostic biomarkers and therapeutic targets for bTBI due to a limited understanding of biological mechanisms, particularly in the early stages. The objective of this study was to examine the early neuropathological characteristics and underlying biological mechanisms of primary bTBI. A total of 83 Sprague Dawley rats were employed, with their heads subjected to a blast shockwave of peak overpressure ranging from 172 to 421 kPa in the GI, GII, and GIII groups within a closed shock tube, while the body was shielded. Neuromotor dysfunctions, morphological changes, and neuropathological alterations were detected through modified neurologic severity scores, brain water content analysis, MRI scans, histological, TUNEL, and caspase-3 immunohistochemical staining. In addition, label-free quantitative (LFQ)-proteomics was utilized to investigate the biological mechanisms associated with the observed neuropathology. Notably, no evident damage was discernible in the GII and GI groups, whereas mild brain injury was observed in the GIII group. Neuropathological features of bTBI were characterized by morphologic changes, including neuronal injury and apoptosis, cerebral edema, and cerebrovascular injury in the shockwave's path. Subsequently, 3153 proteins were identified and quantified in the GIII group, with subsequent enriched neurological responses consistent with pathological findings. Further analysis revealed that signaling pathways such as relaxin signaling, hippo signaling, gap junction, chemokine signaling, and sphingolipid signaling, as well as hub proteins including Prkacb, Adcy5, and various G-protein subunits (Gnai2, Gnai3, Gnao1, Gnb1, Gnb2, Gnb4, and Gnb5), were closely associated with the observed neuropathology. The expression of hub proteins was confirmed via Western blotting. Accordingly, this study proposes signaling pathways and key proteins that exhibit sensitivity to brain injury and are correlated with the early pathologies of bTBI. Furthermore, it highlights the significance of G-protein subunits in bTBI pathophysiology, thereby establishing a theoretical foundation for early diagnosis and treatment strategies for primary bTBI.

Identification and diagnostic potential of serum microRNAs as biomarkers for early detection of Alzheimer's disease.

This study aimed to investigate the differential expression of serum microRNAs in cognitive normal subjects (NC), patients with mild cognitive impairment (MCI), and patients with Alzheimer's disease (AD), with the objective of identifying potential diagnostic biomarkers. A total of 320 clinical samples, including 32 MCI patients, 288 AD patients, and 288 healthy controls, were collected following international standards. The expression of microRNAs in serum was analyzed using the Agilent human microRNA oligonucleotide microarray, and bioinformatics methods were employed to predict target genes and their involvement in AD-related pathways. Among the 122 microRNAs screened, five microRNAs (hsa-miR-208a-5p, hsa-miR-125b-1-3p, hsa-miR-3194-3p, hsa-miR-4652-5p, and hsa-miR-4419a) exhibited differential expression and met quality control standards. Bioinformatics analysis revealed that the target genes of these microRNAs were involved in multiple AD-related pathways, which changed with disease progression. These findings demonstrate significant differences in serum microRNA expression between NC, MCI, and AD patients. Three microRNAs were identified as potential candidates for the development of diagnostic models for MCI and AD. The results highlight the crucial role of microRNAs in the pathogenesis of AD and provide a foundation for the development of novel therapeutic strategies and personalized treatment approaches for AD. This study contributes to the understanding of AD at the molecular level and offers potential avenues for early diagnosis and intervention in AD patients.

A foot structure study of new arch flexibility grading system based on three-dimensional arch volume.

PURPOSE: Different arch structures may cause different foot function injuries. In the past, the arch structure and flexibility of the foot were often defined by the height of the arch, and there was no three-dimensional (3D) structure classification method. In order to form a more complete 3D description, we propose a new classification system of arch volume flexibility (AVF), and then use this new classification system to investigate the relationship between the AVF and arch index (AI), and the arch height flexibility (AHF) and AI, respectively. METHODS: It is proposed to recruit 180 young male adults for the test. We obtained arch volume and AI through 3D scanning and obtained the navicular height through manual measurement. Based on these data, we calculated the AHF and the AVF. Using the quintile method, these arches are divided into very stiff, stiff, neutral, flexible, and very flexible. According to AI value, all arches were divided into cavus, rectus, and planus. The distribution of AVF was compared using χ2 goodness of fit test. The spearman correlation test was used to compare the AHF and AVF. A p < 0.05 indicates that the difference is statistically significant. RESULTS: All participants' plantar data was obtained through 3D scanning, but only 159 of them were complete, so only 318 feet had valid data. The left AHF is (21.23 ± 12.91) mm/kN, and the right AHF is (21.71 ± 12.69) mm/kN. The AVF of the left foot arch is (207.35 ± 118.28) mm3/kg, while the right one is (203.00 ± 117.92) mm3/kg, and the total AVF of the arch was (205.17 ± 117.94) mm3/kg. There was no statistical difference in the AVF between the left and right feet for the same participant (n = 159, p = 0.654). In cavus, the percentage of arch with AVF is 21.4% (very stiff), 21.4% (stiff), 14.3% (neutral), 7.1% (flexible), and 35.7% (very flexible). In rectus, the percentage of arch with AVF is 23.9% (very stiff), 19.6% (stiff), 14.7% (neutral), 24.5% (flexible), and 17.2% (very flexible). In planus, the percentage of arch with AVF is 14.9% (very stiff), 20.6% (stiff), 27.0% (neutral), 16.3% (flexible), and 21.3% (very flexible). Moreover, the correlation between AHF and AVF is not significant (p = 0.060). CONCLUSION: In cavus, rectus, and planus, different AVF accounts different percentage, but the difference is not statistically significant. AVF is evenly distributed in the arches of the feet at different heights. We further found the relationship between AHF and AVF is not significant. As a 3D index, AVF may be able to describe the flexibility of the arch more comprehensively than AHF.

Regulatory pathway underpinning the development of encephalitis after simian immunodeficiency virus infection in rhesus macaques (Macaca mulatta).

BACKGROUND: Simian immunodeficiency virus (SIV) infection in rhesus macaques (Macaca mulatta) can lead to the development of SIV encephalitis (SIVE), which is closely related to human immunodeficiency virus (HIV)-induced dementia. METHODS: This was done by analyzing SIV and SIVE encephalitis in infected M. mulatta hippocampus samples from two microarray data sets, identifying two groups of common differentially expressed genes and predicting associated protein interactions. RESULTS: We found that eight genes-MX1, B2M, IFIT1, TYMP, STAT1, IFI44, ISG15, and IFI27-affected the negative regulation of biological processes, hepatitis C and Epstein-Barr viral infection, and the toll-like receptor signaling pathway, which mediate the development of encephalitis after SIV infection. In particular, STAT1 played a central role in the process by regulating biopathological changes during the development of SIVE. CONCLUSION: These findings provide a new theoretical basis for the treatment of encephalopathy after HIV infection by targeting STAT1.

Effects of different preservation on the mechanical properties of cortical bone under quasi-static and dynamic compression.

Introduction: Mechanical properties of biological tissue are important for numerical simulations. Preservative treatments are necessary for disinfection and long-term storage when conducting biomechanical experimentation on materials. However, few studies have been focused on the effect of preservation on the mechanical properties of bone in a wide strain rate. The purpose of this study was to evaluate the influence of formalin and dehydration on the intrinsic mechanical properties of cortical bone from quasi-static to dynamic compression. Methods: Cube specimens were prepared from pig femur and divided into three groups (fresh, formalin, and dehydration). All samples underwent static and dynamic compression at a strain rate from 10-3 s-1 to 103 s-1. The ultimate stress, ultimate strain, elastic modulus, and strain-rate sensitivity exponent were calculated. A one-way ANOVA test was performed to determine if the preservation method showed significant differences in mechanical properties under at different strain rates. The morphology of the macroscopic and microscopic structure of bones was observed. Results: The results show that ultimate stress and ultimate strain increased as the strain rate increased, while the elastic modulus decreased. Formalin fixation and dehydration did not affect elastic modulus significantly whereas significantly increased the ultimate strain and ultimate stress. The strain-rate sensitivity exponent was the highest in the fresh group, followed by the formalin group and dehydration group. Different fracture mechanisms were observed on the fractured surface, with fresh and preserved bone tending to fracture along the oblique direction, and dried bone tending to fracture along the axial direction. Discussion: In conclusion, preservation with both formalin and dehydration showed an influence on mechanical properties. The influence of the preservation method on material properties should be fully considered in developing a numerical simulation model, especially for high strain rate simulation.

Research on skeletal muscle impact injury using a new rat model from a bioimpact machine.

Introduction: Skeletal muscle impact injury occurs frequently during sports, falls, and road traffic accidents. From the reported studies on skeletal muscle injury, it is difficult to determine the injury parameters. Therefore, we developed a new model of gastrocnemius impact injury in rats with a bioimpact machine, with which the experimental operation could be conducted in feasibility from the recorded parameters. Through this novel model, we study the skeletal muscle impact injury mechanisms by combining temporal and spatial variation. Methods: The gastrocnemius of anesthetized rats was injured by a small pneumatic-driven bioimpact machine; the moving speed and impact force were determined, and the whole impact process was captured by a high-speed camera. We observed the general condition of rats and measured the changes in injured calf circumference, evaluating calf injuries using MRI, gait analysis system, and pathology at different times after the injury. Results: The gastrocnemius was injured at an impact speed of 6.63 m/s ± 0.25 m/s and a peak force of 1,556.80 N ± 110.79 N. The gait analysis system showed that the footprint area of the RH limb decreased significantly on the first day and then increased. The calf circumference of the injured limb increased rapidly on the first day post-injury and then decreased in the next few days. MRI showed edema of subcutaneous and gastrocnemius on the first day, and the area of edema decreased over the following days. HE staining showed edema of cells, extensive hyperemia of blood vessels, and infiltration of inflammatory cells on the first day. Cell edema was alleviated day by day, but inflammatory cell infiltration was the most on the third day. TEM showed that the sarcoplasmic reticulum was dilated on the first day, the mitochondrial vacuolation was obvious on the second day, and the glycogen deposition was prominent on the fifth day. Conclusion: In our experiment, we developed a new and effective experimental animal model that was feasible to operate; the injured area of the gastrocnemius began to show "map-like" changes in the light microscope on the third day. Meanwhile, the gastrocnemius showed a trend of "edema-mitochondrial vacuolation-inflammatory cell aggregation" after impact injury.

Biomechanical analysis of thorax-abdomen response of vehicle occupant under seat belt load considering different frontal crash pulses.

PURPOSE: The purpose of this work was to understand the biomechanical response and injury risk of thorax and abdomen of vehicle front seat occupants caused by seat belt load under different frontal crash pulses. METHODS: A vehicle-seat-occupant subsystem finite element (FE) model was developed using the a assembly of vehicle front seat and seat belt together with the THUMS (Total Human body Model for Safety) AM50 (50th% Adult Male) occupant model. Then the typical vehicle frontal crash pulses from different impact scenarios were applied to the vehicle-seat-occupant subsystem FE model, and the predictions from the occupant model were analyzed. RESULTS: The modeling results indicate that the maximum sternal compression of the occupant caused by seat belt load is not sensitive to the peek of the crash pulse but sensitive to the energy contained by the crash pulse in the phrase before seat belt load reaching its limit. Injury risk analysis implies that seat belt load of the four crash scenarios considered in the current work could induce a high thorax AIS2+ injury risk (>80%) to the occupants older than 70 years, and a potential injury risk to the spleen. CONCLUSIONS: The findings suggest that control of the energy in the first 75 ms of the crash pulse is crucial for vehicle safety design, and thorax tolerance of the older population and spleen injury prevention are the key considerations in developing of seat belt system.

Effect of Low-Frequency Vibration on Muscle Response under Different Neurointact Conditions.

Stretch reflex is an important factor that influences the biomechanical response of the human body under whole-body vibration. However, there is a lack of quantitative evaluation at lower frequencies. Thus, the aim of this study was to investigate the effects of vibration on the stretch reflex and, in particular, to explore the quantitative relationship between dynamic muscle responses and low-frequency vibrations. The gastrocnemius muscle of 45 Sprague-Dawley rats was dissected. Sinusoidal vibrations of five discrete frequencies (2~16 Hz) with peak-to-peak amplitudes of 1 mm were applied to the gastrocnemius muscles with 2 mm or 3 mm prelengthening. Variables including dynamic muscle force, vibration acceleration, and displacement were recorded in two conditions, with and without the stretch reflex. Results showed that the dynamic muscle forces decreased by 20% on average for the 2 mm prelengthening group after the stretch reflex was blocked and by 24% for the 3 mm prelengthening group. Statistical analysis indicated that the amplitude of dynamic muscle force in the "with stretch reflex" condition was significantly larger than that in the "without stretch reflex" condition (p < 0.001). The tension-length curve was found to be a nonlinear hysteresis loop that changed with frequency. The phase difference between the dynamic muscle force and the length change was affected significantly by vibration frequency (p < 0.01), and the minimum frequency was 4-8 Hz. Experimental results of this study could benefit musculoskeletal model by providing a theoretical support to build a stretch reflex model for low-frequency vibration.

Effects of altitude changes on mild-to-moderate closed-head injury in rats following acute high-altitude exposure.

Mild-to-moderate closed-head injury (mmCHI) is an acute disease induced by high-altitudes. It is general practice to transfer patients to lower altitudes for treatment, but the pathophysiological changes at different altitudes following mmCHI remain unknown. The present study simulated acute high-altitude exposure (6,000 m above sea level) in rats to establish a model of mmCHI and recorded their vital signs. The rats were then randomly assigned into different altitude exposure groups (6,000, 4,500 and 3,000 m) and neurological severity score (NSS), body weight (BW), brain magnetic resonance imaging (MRI), brain water content (BWC) and the ratio of BW/BWC at 6, 12 and 24 h following mmCHI, and the glial fibrillary acidic protein levels were analysed in all groups. The results revealed that within the first 24 h following acute high-altitude exposure, mmCHI induced dehydration, brain oedema and neuronal damage. Brain injury in rats was significantly reversed following descent to 4,500 m compared with the results from 6,000 or 3,000 m. The results indicated that subjects should be transported as early as possible. Furthermore, avoiding large-span descent altitude was beneficial to reduce neurological impairment. The examination of brain-specific biomarkers and MRI may further be useful in determining the prognosis of high-altitude mmCHI. These results may provide guidance for rescuing high altitude injuries.

Novel-graded traumatic brain injury model in rats induced by closed head impacts.

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Due to the heterogeneity of human TBI, none of the available animal models can reproduce the entire spectrum of TBI. This study was designed to develop a novel-graded TBI rat model which is induced by closed head impacts (CHI) with reproducible brain damage and neurological dysfunction. A total of 75 male Sprague-Dawley rats (200 ± 20 g) were randomly equally divided into five groups: the Sham, 0.5, 0.6, 0.7 and 0.8 MPa groups. A custom-made, air-driven injury apparatus was used to induce CHIs (from 0.5 to 0.8 MPa). The kinematic parameters during the procedure were recorded by a force sensor and a high-speed camera. Mortality rate, duration of unconsciousness (latency period of righting reflex), modified neurological severity score (mNSS) and whole brain water content (BWC) were examined. Pathological changes were evaluated by hematoxylin-eosin (HE) stain and immunohistochemical stain for amyloid precursor protein (APP). The impact force and speed were 785.3 ± 14.12 N and 5.71 m/s in the 0.5 MPa group, 837.72 ± 10.41 N and 6.06 m/s in the 0.6 MPa group, 857.65 ± 11.11 N and 6.25 m/s in the 0.7 MPa group, and 955.6 ± 16.35 N and 6.67 m/s in the 0.8 MPa group. The periods of loss of righting reflex in 0.6-0.8 MPa groups were significantly higher than that in the Sham group. The mNSS score and BWC of the 0.8 MPa group remained higher 24 h after injury than other groups. Brain damage was indicated by increased APP expression in TBI rats. In conclusion, the newly developed CHI rat model was a highly controlled and reproducible graded TBI model, and provided a useful tool to investigate the underlying mechanism and therapeutic effects of TBI with various injury severities.

Ultrastretchable Fiber Sensor with High Sensitivity in Whole Workable Range for Wearable Electronics and Implantable Medicine.

Fast progress in material science has led to the development of flexible and stretchable wearable sensing electronics. However, mechanical mismatches between the devices and soft human tissue usually impact the sensing performance. An effective way to solve this problem is to develop mechanically superelastic and compatible sensors that have high sensitivity in whole workable strain range. Here, a buckled sheath-core fiber-based ultrastretchable sensor with enormous stain gauge enhancement is reported. Owing to its unique sheath and buckled microstructure on a multilayered carbon nanotube/thermal plastic elastomer composite, the fiber strain sensor has a large workable strain range (>1135%), fast response time (≈16 ms), high sensitivity (GF of 21.3 at 0-150%, and 34.22 at 200-1135%), and repeatability and stability (20 000 cycles load/unload test). These features endow the sensor with a strong ability to monitor both subtle and large muscle motions of the human body. Moreover, attaching the sensor to a rat tendon as an implantable device allowes quantitative evaluation of tendon injury rehabilitation.

Biomechanical Responses and Injury Characteristics of Knee Joints under Longitudinal Impacts of Different Velocities.

BACKGROUND AND OBJECTIVE: Knee joint collision injuries occur frequently in military and civilian scenarios, but there are few studies assessing longitudinal impacts on knee joints. In this study, the mechanical responses and damage characteristics of knee longitudinal collisions were investigated by finite element analysis and human knee impact tests. MATERIALS AND METHODS: Based on a biocollision test plateau, longitudinal impact experiments were performed on 4 human knee joints (2 in the left knee and 2 in the right knee) to measure the impact force and stress response of the bone. And then a finite element model of knee joint was established from the Chinese Visible Human (CVH), with which longitudinal impacts to the knee joint were simulated, in which the stress response was determined. The injury response of the knee joint-sustained longitudinal impacts was analyzed from both the experimental model and finite element analysis. RESULTS: The impact experiments and finite element simulation found that low-speed impact mainly led to medial injuries and high-speed impact led to both medial and lateral injuries. In the knee joint impact experiment, the peak flexion angles were 13.8° ± 1.2, 30.2° ± 5.1, and 92.9° ± 5.45 and the angular velocities were 344.2 ± 30.8 rad/s, 1510.8 ± 252.5 rad/s, and 9290 ± 545 rad/s at impact velocities 2.5 km/h, 5 km/h, and 8 km/h, respectively. When the impact velocity was 8 km/h, 1 knee had a femoral condylar fracture and 3 knees had medial tibial plateau fractures or collapse fractures. The finite element simulation of knee joints found that medial cortical bone stress appeared earlier than the lateral peak and that the medial bone stress concentration was more obvious when the knee was longitudinally impacted. CONCLUSION: Both the experiment and FE model confirmed that the biomechanical characteristics of the injured femur and medial tibia are likely to be damaged in a longitudinal impact, which is of great significance for the prevention and treatment of longitudinal impact injuries of the knee joint.

Experimental Study of Thoracoabdominal Injuries Suffered from Caudocephalad Impacts Using Pigs.

To know the caudocephalad impact- (CCI-) induced injuries more clearly, 21 adult minipigs, randomly divided into three groups: control group (n = 3), group I (n = 9), and group II (n = 9), were used to perform the CCI experiments on a modified deceleration sled. Configured impact velocity was 0 m/s in the control group, 8 m/s in group I, and 11 m/s in group II. The kinematics and mechanical responses of the subjects were recorded and investigated. The functional change examination and the autopsies were carried out, with which the injuries were evaluated from the Abbreviated Injury Scale (AIS) and the Injury Severity Score (ISS). The subjects in group I and group II experienced the caudocephalad loading at the peak pelvic accelerations of 108.92 ± 58.87 g and 139.13 g ± 78.54 g, with the peak abdomen pressures, 41.24 ± 16.89 kPa and 63.61 ± 65.83 kPa, respectively. The injuries of the spleen, lung, heart, and spine were detected frequently among the tested subjects. The maximal AIS (MAIS) of chest injuries was 4 in group I and 5 in group II, while both the MAIS of abdomen injuries in group I and group II were 5. The ISS in group II was 52.71 ± 6.13, significantly higher than in group I, 26.67 ± 5.02 (p < 0.05). The thoracoabdomen CCI injuries and the mechanical response addressed presently may be useful to conduct both the prevention studies against military or civilian injuries.

Preliminary study on alterations of altitude road traffic in China from 2006 to 2013.

INTRODUCTION: Road traffic can play an important role in strengthening regional economic activities, especially at high altitude, and it is necessary to know important traffic-related information. Although previous studies reported on road traffic in China, there has been little research on high-altitude road traffic to date. METHOD: The annual official census of road traffic safety from 2006 to 2013 was used to obtain data on the general population, registered drivers, registered vehicles, newly built roads, road traffic accidents (RTAs), mortality rate per 100 000 populations and per 10 000 vehicles in high-altitude provinces, including Tibet, Qinghai, Xinjiang, Gansu, Yunnan, Sichuan, and Chongqing. These provincial data were reviewed retrospectively, with the national data as the reference. Statistical analysis (i.e., t test) was used to compare the estimated average annual change rate of population, number of registered drivers, registered vehicles, and newly built roads in high-altitude provinces with the national rates. RESULTS: Compared with the national data, there are significantly higher annual rates of population growth in Tibet and Xinjiang, registered drivers in Gansu, registered vehicles in Gansu, Sichuan, and Chongqing, and newly built roads in Tibet and Qinghai. Among the investigated provinces, Tibet, Qinghai, and Yunnan had a higher proportion of the roads with the high class. RTAs and RTA-induced casualties in the high-altitude provinces indicated a decreasing trend. The mortality rate per 10 000 vehicles and per 100 000 populations showed a decreasing trend, while the RTA-related mortality rate in Tibet, Qinghai, Xinjiang and Gansu remained high. CONCLUSIONS: Major changes for road traffic in high-altitude provinces have occurred over the past decade; however, the RTA-related mortality rate in high-altitude provinces has remained high. This study furthers understanding about road traffic safety in China; further studies on road traffic safety at high altitude should be performed.

Mechanical Characterization of Immature Porcine Brainstem in Tension at Dynamic Strain Rates.

BACKGROUND: Many brain injury cases involve pediatric road traffic accidents, and among these, brainstem injury causes disastrous outcomes. A thorough understanding of the tensile characterization of immature brainstem tissue is crucial in modeling traumatic brain injury sustained by children, but limited experimental data in tension is available for the immature brain tissue at dynamic strain rates. MATERIAL AND METHODS: We harvested brainstem tissue from immature pigs (about 4 weeks old, and at a developmental stage similar to that of human toddlers) as a byproduct from a local slaughter house and very carefully prepared the samples. Tensile tests were performed on specimens at dynamic strain rates of 2/s, 20/s, and 100/s using a biological material instrument. The constitutive models, Fung, Ogden, Gent, and exponential function, for immature brainstem tissue material property were developed for the recorded experimental data using OriginPro 8.0 software. The t test was performed for infinitesimal shear modules. RESULTS: The curves of stress-versus-stretch ratio were convex in shape, and inflection points were found in all the test groups at the strain of about 2.5%. The average Lagrange stress of the immature brainstem specimen at the 30% strain at the strain rates of 2, 20, and 100/s was 273±114, 515±107, and 1121±197 Pa, respectively. The adjusted R-Square (R2) of Fung, Ogden, Gent, and exponential model was 0.820≤R2≤0.933, 0.774≤R2≤0.940, 0.650≤R2≤0.922, and 0.852≤R2≤0.981, respectively. The infinitesimal shear modulus of the strain energy functions showed a significant association with the strain rate (p<0.01). CONCLUSIONS: The immature brainstem is a rate-dependent material in dynamic tensile tests, and the tissue becomes stiffer with increased strain rate. The reported results may be useful in the study of brain injuries in children who sustain injuries in road traffic accidents. Further research in more detail should be performed in the future.