Background： The increasing frequency of explosive injuries has increased interest in blast-induced traumatic brain injury （bTBI）. Various shock tube models have been used to study bTBI. Mild-to-moderate explosions ...Background： The increasing frequency of explosive injuries has increased interest in blast-induced traumatic brain injury （bTBI）. Various shock tube models have been used to study bTBI. Mild-to-moderate explosions are often overlooked because of the slow onset or mildness of the symptoms. However, heavy gas cylinders and large volume chambers in the model may increase the complexity and danger. This study sought to design a modified model to explore the effect of moderate explosion on brain injury in mice. Methods： Pathology scoring system （PSS） was used to distinguish the graded intensity by the modified model. A total of 160 mice were randomly divided into control, sham, and bTBI groups with different time points. The clinical features, imaging features, neurobehavior, and neuropathology were detected after moderate explosion. One-way analysis of variance followed by Fisher＇s least significant difference posttest or Dunnett＇s t 3-test was performed for data analyses. Results： PSS of mild, moderate, and severe explosion was 13.4 ± 2.2, 32.6 ± 2.7 （t = 13.92, P 〈 0.001; vs. mild group）, and 56.6 ± 2.8 （t = 31.37, P 〈 0.001; vs. mild group）, respectively. After moderate explosion, mice showed varied symptoms of malaise, anorexia, incontinence, apnea, or seizure. After bTBI, brain edema reached the highest peak at day 3 （82.5% ± 2.1% vs. 73.8% ± 0.6%. t - 7.76, P 〈 0.001）, while the most serious neurological outcomes occurred at day 1 （Y-maze： 8.25 ±2.36 vs. 20.00 ± 4.55, t = -4.59, P=0.048; 29.58% ± 2.84% vs. 49.09% ±11.63%, t = -3.08, P = 0.008; neurologic severity score： 2.50 ± 0.58 vs. 0.00±0.00, t = 8.65, P = 0.016）. We also found that apoptotic neurons （52.76% ± 1.99% vs. 1.30% ± 0.11%, t =57.20, P 〈 0.001 ） and gliosis （2.98 ± 0.24 vs. 1.00 ± 0.00, t = 14.42, P = 0.021） in the frontal were significantly higher at day 3 post-bTBI than sham bTB1. Conclusions： We provide a reliable, reproducible bTBI model in mice that can produce a graded explosive waveform similar to the free-field shock wave in a controlled laboratory environment. Moderate explosion can trigger mild-to-moderate blast damage of the brain.展开更多
Blast-induced traumatic brain injury(b-TBI)is a kind of significant injury to soldiers in the current military conflicts.However,the mechanism of b-TBI has not been well understood,and even there are some contradictor...Blast-induced traumatic brain injury(b-TBI)is a kind of significant injury to soldiers in the current military conflicts.However,the mechanism of b-TBI has not been well understood,and even there are some contradictory conclusions.It is crucial to reveal the dynamic mechanism of brain volume and shear deformations under blast loading for better understanding of b-TBI.In this paper,the numerical simulation method is adopted to carry out comprehensive and in-depth researches on this issue for the first time.Based on the coupled Eulerian-Lagrangian method,the fluid-structure coupling model of the blast wave and human head is developed to simulate two situations,namely the head subjected to the frontal and lateral impacts.The simulation results are analyzed to obtain the underlying dynamic mechanisms of brain deformation.The brain volume deformation is dominated by the local bending vibration of the skull,and the corresponding frequency for the forehead skull under the frontal impact and the lateral skull faced to the lateral impact is as high as 8 kHz and 5 kHz,respectively.This leads to the high-frequency fluctuation of brain pressure and the large pressure gradient along the skull,totally different from the dynamic response of brain under head collisions.While the brain shear deformation mainly depends on the relative tangential displacement between the skull and brain and the anatomical structure of inner skull,being not related to the brain pressure and its gradient.By further comparing the medical statistics,it is inferred that diffuse axonal injury and brain contusion,the two most common types of b-TBI,are mainly attributed to brain shear deformations.And the von Mises stress can be adopted as the indicator for these two brain injuries.This study can provide theoretical guidance for the diagnosis of b-TBI and the development of protective equipment.展开更多
文摘Background： The increasing frequency of explosive injuries has increased interest in blast-induced traumatic brain injury （bTBI）. Various shock tube models have been used to study bTBI. Mild-to-moderate explosions are often overlooked because of the slow onset or mildness of the symptoms. However, heavy gas cylinders and large volume chambers in the model may increase the complexity and danger. This study sought to design a modified model to explore the effect of moderate explosion on brain injury in mice. Methods： Pathology scoring system （PSS） was used to distinguish the graded intensity by the modified model. A total of 160 mice were randomly divided into control, sham, and bTBI groups with different time points. The clinical features, imaging features, neurobehavior, and neuropathology were detected after moderate explosion. One-way analysis of variance followed by Fisher＇s least significant difference posttest or Dunnett＇s t 3-test was performed for data analyses. Results： PSS of mild, moderate, and severe explosion was 13.4 ± 2.2, 32.6 ± 2.7 （t = 13.92, P 〈 0.001; vs. mild group）, and 56.6 ± 2.8 （t = 31.37, P 〈 0.001; vs. mild group）, respectively. After moderate explosion, mice showed varied symptoms of malaise, anorexia, incontinence, apnea, or seizure. After bTBI, brain edema reached the highest peak at day 3 （82.5% ± 2.1% vs. 73.8% ± 0.6%. t - 7.76, P 〈 0.001）, while the most serious neurological outcomes occurred at day 1 （Y-maze： 8.25 ±2.36 vs. 20.00 ± 4.55, t = -4.59, P=0.048; 29.58% ± 2.84% vs. 49.09% ±11.63%, t = -3.08, P = 0.008; neurologic severity score： 2.50 ± 0.58 vs. 0.00±0.00, t = 8.65, P = 0.016）. We also found that apoptotic neurons （52.76% ± 1.99% vs. 1.30% ± 0.11%, t =57.20, P 〈 0.001 ） and gliosis （2.98 ± 0.24 vs. 1.00 ± 0.00, t = 14.42, P = 0.021） in the frontal were significantly higher at day 3 post-bTBI than sham bTB1. Conclusions： We provide a reliable, reproducible bTBI model in mice that can produce a graded explosive waveform similar to the free-field shock wave in a controlled laboratory environment. Moderate explosion can trigger mild-to-moderate blast damage of the brain.
文摘Blast-induced traumatic brain injury(b-TBI)is a kind of significant injury to soldiers in the current military conflicts.However,the mechanism of b-TBI has not been well understood,and even there are some contradictory conclusions.It is crucial to reveal the dynamic mechanism of brain volume and shear deformations under blast loading for better understanding of b-TBI.In this paper,the numerical simulation method is adopted to carry out comprehensive and in-depth researches on this issue for the first time.Based on the coupled Eulerian-Lagrangian method,the fluid-structure coupling model of the blast wave and human head is developed to simulate two situations,namely the head subjected to the frontal and lateral impacts.The simulation results are analyzed to obtain the underlying dynamic mechanisms of brain deformation.The brain volume deformation is dominated by the local bending vibration of the skull,and the corresponding frequency for the forehead skull under the frontal impact and the lateral skull faced to the lateral impact is as high as 8 kHz and 5 kHz,respectively.This leads to the high-frequency fluctuation of brain pressure and the large pressure gradient along the skull,totally different from the dynamic response of brain under head collisions.While the brain shear deformation mainly depends on the relative tangential displacement between the skull and brain and the anatomical structure of inner skull,being not related to the brain pressure and its gradient.By further comparing the medical statistics,it is inferred that diffuse axonal injury and brain contusion,the two most common types of b-TBI,are mainly attributed to brain shear deformations.And the von Mises stress can be adopted as the indicator for these two brain injuries.This study can provide theoretical guidance for the diagnosis of b-TBI and the development of protective equipment.
