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Objective To study influencing factors of renal blunt impact injury by using finite element (FE) method. Methods Based on CT images of the kidney, the kidney FE models for different age groups were constructed. The renal blunt impact test was reconstructed, and the influence of kidney material constitutive parameters, kidney tissue structure, kidney size, impact position and impact velocity on injury severity were analyzed. Results Under the same impact condition, the stress of renal cortex decreased with the kidney mass increasing, and increased with the impact velocity of the hammer increasing. The renal capsule had a certain energy absorption effect, so as to reduce the kidney stress. When the kidney was impacted, the stress of renal cortex under side impact was significantly higher than that under frontal impact. Conclusions Compared with viscoelastic constitutive model, Mooney Rivlin material constitutive model is more suitable for FE evaluation on renal injury severity. The renal injury decreases with the kidney mass increasing. The increase of impact velocity will intensify the renal injury severity. Renal capsule will reduce renal injury to a certain extent, so the existence of renal capsule structure must be considered in FE modeling of the kidney. Compared with frontal and rear impact, the renal injury severity is greater when the kidney is impacted from the lateral side.
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The finite element method is a new method to study the mechanism of brain injury caused by blunt instruments. But it is not easy to be applied because of its technology barrier of time-consuming and strong professionalism. In this study, a rapid and quantitative evaluation method was investigated to analyze the craniocerebral injury induced by blunt sticks based on convolutional neural network and finite element method. The velocity curve of stick struck and the maximum principal strain of brain tissue (cerebrum, corpus callosum, cerebellum and brainstem) from the finite element simulation were used as the input and output parameters of the convolutional neural network The convolutional neural network was trained and optimized by using the 10-fold cross-validation method. The Mean Absolute Error (MAE), Mean Square Error (MSE), and Goodness of Fit ( R 2) of the finally selected convolutional neural network model for the prediction of the maximum principal strain of the cerebrum were 0.084, 0.014, and 0.92, respectively. The predicted results of the maximum principal strain of the corpus callosum were 0.062, 0.007, 0.90, respectively. The predicted results of the maximum principal strain of the cerebellum and brainstem were 0.075, 0.011, and 0.94, respectively. These results show that the research and development of the deep convolutional neural network can quickly and accurately assess the local brain injury caused by the sticks blow, and have important application value for understanding the quantitative evaluation and the brain injury caused by the sticks struck. At the same time, this technology improves the computational efficiency and can provide a basis reference for transforming the current acceleration-based brain injury research into a focus on local brain injury research.
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Humans , Brain , Brain Injuries , Computer Simulation , Finite Element Analysis , Neural Networks, ComputerABSTRACT
Objective To predict and assess biomechanical responses and injury mechanisms of the thorax and abdomen for small-sized females in vehicle collisions. Methods The accurate geometric model of the thorax and abdomen was constructed based on CT images of Chinese 5th percentile female volunteers. A thoracic-abdominal finite element model of Chinese 5th percentile female with detailed anatomical structure was developed by using the corresponding software. The model was validated by reconstructing three groups of cadaver experiments (namely, test of blunt anteroposterior impact on the thorax, test of bar anteroposterior impact on the abdomen, test of blunt lateral impact on the chest and abdomen). Results The force-deformation curves and injury biomechanical responses of the organs from the simulations were consistent with the cadaver experiment results, which validated effectiveness of the model. Conclusions The model can be used for studying injury mechanisms of the thorax and abdomen for small-sized female, as well as developing small-sized occupant restraint systems and analyzing the forensic cases, which lays foundation for developing the whole body finite element model of Chinese 5th percentile female.
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Objective Based on the anthropomorphic phantom experiment and Monte Carlo simulation, the patients’ skin dose, professionals’ dose, and spatial distribution of DSA (Digital Subtraction Angiography) radiation field in an intervention procedure, was performed, in order to provide the basis for the inference of patients’ skin injury and professionals’ radiation protection in intervention procedure. Methods In the simulation experiment, a PBU-60 anthropomorphic phantom was used as the patient and the skin dose of patient’s abdomen was measured by TLD (Thermoluminescence Dosimeters). X-ray and gamma radiation dosimeter (AT1121) was applied to measure the spatial distribution of DSA radiation field, which was verified using Monte Carlo software MCNP meanwhile. Furthermore, the radiation dosimetry of operative staffs at different stations and under different protection conditions was studied experimentally. Results The experimental measurements showed that the maximum skin dose of patients every 5-minute fluoroscopy was 18.62 mGy under the irradiation of PA in an abdominal interventional procedure. The results of Monte Carlo simulation and measurement experiments showed that the spatial distribution of DSA radiation fieldis similar to the butterfly distribution, which is related to distance and angle. The experimental results showed that the dose rate decreases exponentially with the increase of lead equivalent. Conclusion It is very significant to carry out skin dose measurementof patients during interventional surgery and follow-up patients with high dose after surgery. In interventional surgery, doctors should try to avoid the station of high dose rate. However, it is necessary to strengthen the radiation protection of the operator and the first assistant. Under the dual protections of bedside lead protective equipment and personal protective equipment, the exposure dose of intervention personnel can be significantly reduced.
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Objective To explore the influence of child head injury under different impact angles by applying the finite element model of six-year-old child pedestrian as specified in the European New Car Assessment Programme (Euro NCAP). Methods Based on the finite element model of 6-year-old pedestrian with detailed anatomical structure as specified by the Euro NCAP (TB024), four groups of simulation experiments were set up to explore the mechanism of head injury in children under different impact angles. The initial position for head mass center was on the longitudinal center line of the car. The initial speed of the car was 40 km/h. The car contacted with the model from the direction of the right (0°), the front (90°), the left (180°) and the back (270°). The kinematics differences and head impact responses were compared, and injuries of the facial bone and skull were analyzed. Results Through the analysis of head contact force, acceleration of head mass center, resultant velocity of head mass center with the vehicle, head injury criterion (HIC15), facial bone fracture and skull stress distribution, it was found that the risk of head fracture and brain contusion under back impact and front impact was higher than that under side impact. The risk of head fracture and brain contusion was highest under back impact, while the lowest under side impact. Conclusions Child pedestrian head injury was the largest under back impact. The results have important application values for the assessment and development of car-pedestrian collision protection device.
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Objective To study the constitutive model of adipose tissue at medium strain rate and its parameter inversion. Methods Based on experiments of adipose tissue mechanical properties, the compression experiment of adipose tissues was reconstructed by finite element method, and the parameters for characterizing constitutive models of adipose tissues were screened. Combined with the method of feasible direction (MFD) in optimization method, the reverse calculation for parameters of fat tissue constitutive model at medium strain rate was conducted. ResultsCompared with Ogden constitutive model, the viscoelastic constitutive model was more suitable for characterizing the mechanical response at medium strain rate (260 s-1). The parameters of the constitutive model suitable for simulation were obtained using the reverse method. Conclusions The viscoelastic constitutive model was more suitable for characterizing the mechanical response at medium strain rate. The results provide references for studying the influence of human adipose tissues on body injury in finite element simulation of vehicle collisions.
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Objective To study the influence of skull thickness on intracranial biomechanical parameters by finite element method. Methods The female head at 5th percentile was selected for CT scanning to construct finite element model of the head with high biofidelity,and the model was verified by reconstructed cadaver test. The finite element model of the head with different skull thickness was established, and multiple groups of tests were carried out to compare the intracranial mechanical parameters. Results The negative value of intracranial pressure was significantly affected by the decrease in skull thickness under the same head size, while the negative value of intracranial pressure was slightly affected, with an increasing trend. The shear stress and von Mises stress of brain tissues were significantly increased with skull thickness increasing. Conclusions Under the same head size, the skull thickness will affect head injury to a certain extent, and people with small skull thickness are more likely to be injured than those with large skull thickness.
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Objective To explore the effect of restraint system misuse on head-neck injuries for rear occupant of 6-year-old children in frontal impact crashes. Methods Based on the previously validated 6-year-old child occupant finite element model, in terms of ECE R44 testing regulations, the impact crash under right and wrong use of restraint system was simulated in Pam-Crash software. Results The force and moment of the neck were the minimum by merely using booster seat, but the maximum intracranial pressure, the maximum stress and the maximum principal strain were larger than their damage threshold and would cause fatal brain damage in child head. The only use of adult safety belt would cause more serious damage in child neck with larger force and moment. Conclusions Two ways of misusing the restraint system would aggravate head-neck injuries of the 6-year-old child. The proper use of the restraint system can provide the best protective effect for head and neck of the 6-year-old child occupant.
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Objective To study the effect of neck restrain on traumatic brain injury during airbag inflation in traffic accidents. Methods Based on the previously validated 3-year-old child head finite element (FE) model, the impact on out-of-position (OOP) child occupant during airbag inflation was simulated by FE method, so as to investigate the effects of neck restraint on intracranial response and injury mechanism in traffic accidents. Results The head kinematics with neck restrain was different from that without neck restrain under the impact of airbag inflation. The neck restraint would obviously decrease the maximum Von Mises stress of pediatric brain. When airbag-head distance was 20 cm or 25 cm, the neck restraint would obviously decrease the maximum intracranial pressure. Conclusions Neck restraint had a relatively large influence on pediatric intracranial response. When the FE method is used to predict pediatric craniocerebral injury, consideration of neck restrain on child brain response is necessary.
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Objective To explore the effects of different skull-brain interfaces and mesh density of the cerebrospinal fluid (CSF) on dynamic responses of the brain. Methods The impact kinematics on cadaver head under rotation and translation impacts were reconstructed based on the 50th percentile adult head finite element model. The interfaces between skull and CSF, CSF and brain were modeled with different types of interfaces, which were set as sharing nodes, tied, frictionless sliding, so as to investigate the effect of different interface types on dynamic responses of the brain. Then, the interfaces between CSF, skull and brain were set as sharing nodes, while CSF was divided into single-layer and tri-layer of hexahedral element with the constant thickness of CSF, to study influences of CSF with different mesh density layers on dynamic responses of the brain. Results The intracranial pressure was highly sensitive to the interface types, while the brain response seemed to be relatively insensitive to the variation in CSF layers. Conclusions The research findings provide theoretical references for the construction of CSF and the selection of skull-brain contact interface of the head finite element model.
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Modern vehicle safety design and safety regulations are mostly based on 50th percentile populations. However, with the increase of obese populations, it is very important to investigate the injury mechanism and protection of obese occupant. Methods such as traffic accidents statistics, cadaver experiments, multi-body modeling and finite element modeling, are currently used to study the injury mechanism of obese occupants. Different hypotheses including cushion effect, body geometrical effect and mass increasing effect have been put forward to explain the effect of obesity on occupant injury mechanism, which means that its mechanism is still uncertain. The impact injury mechanisms of obese occupant were comprehensively summarized. Furthermore, the problems confronted by the research of current obese occupant impact injury and future investigations were proposed in this study.
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Objective To compare the effects of losartan and irbesartan on blood pressure,blood uric acid,insulin sensitivity and insulin resistance in female hypertensive patients complicated with hyperuricemia.Methods From August 2015 to December 2017,100 females of hypertension complicated with hyperuricemia who hospitalized in the Third People's Hospital of Ningxia were enrolled in the study.All the patients were divided into two groups according to the random digital table,with 50 cases in each group.The observation group was treated with losartan,and the control group was treated with irbesartan for 8 weeks.The total effective rate and adverse reactions were compared between the two groups.Also the changes of blood pressure,serum uric acid,fasting glucose (FBG),fasting insulin (FINS),high sensitivity C-reactive protein (hs-CRP),insulin sensitivity index (ISI) and insulin resistance index (HOMA-IR) were compared between the two groups after treatment.Results There was no statistically significant difference in the total effective rate between the two groups [92.0％ (46/50) vs.90.0％ (45/50)] (P ＞ 0.05).Before treatment,there were no statistically significant differences in blood pressure,serum uric acid,FBG,FINS,hs-CRP,ISI and HOMA-IR between the two groups (all P ＞ 0.05).After treatment,the systolic blood pressure and diastolic blood pressure in the two groups were (133.09 ± 10.11) mmHg vs.(131.54 ± 11.01) mmHg and (82.76 ± 6.23) mmHg vs.(83.75 ± 6.88) mmHg,which were lower than those before treatment (observation group:t =19.742,10.606,control group:t =18.925,-9.956,all P ＜ 0.05).But there were no statistically significant differences between the two groups (all P ＞ 0.05).After treatment,the serum uric acid in the observation group was lower than that in the control group [(387.21 ± 25.56) μmol/L vs.(429.67 ± 27.44) μmol/L] (t =8.006,P ＜ 0.05).The hs-CRP,FINS,HOMA-IR,ISI in the observation group were (4.92 ± 1.02) rmg/L,(15.92 ± 3.01) mU/L,(1.71 ± 0.24),(1.047 ± 0.095),which in the control group were (4.54 ± 1.00) mg/L,(17.23 ± 3.20) mU/L,(1.65 ± 0.27),(1.140 ± 0.083).After treatment,the hs-CRP,FINS,HOMA-IR in the two groups were decreased (all P ＜ 0.05),while ISI was increased (P ＜ 0.05).Furthermore,the improvement of FINS,ISI and HOMA-IR in the observation group was better than those in the control group (t =2.109,-5.213,3.191,all P ＜ 0.05).Conclusion Both losartan and irbesartan can improve clinical symptoms,lower blood pressure and improve insulin resistance in female hypertension patients complicated with hyperuricemia,and losartan is more effective than irbesartan.
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Objective To compare and analyze the effect of membrane element and spring element on biomechanical responses of cervical ligaments. Methods Based on the existing 6-year-old pediatric neck finite element model, the ligaments were simulated by membrane element and spring element, respectively. Then dynamic tensile test of C4-5 vertebrae and tensile test of full cervical spine were conducted. The membrane element model was also used to simulate the bending test, and the simulation results were analyzed. Results In dynamic tensile test of C4-5 vertebral segment, the final failure force of membrane element simulation test and spring element simulation test was 1 207 N and 842 N, respectively, and their difference from the cadaver experiment was 0.6% and 30.6%, respectively. In full cervical tensile test, the difference of peak force from membrane element simulation test and cadaver experiment was 1.8%. The peak force of spring element simulation test was 484 N, and the difference from simulation test and cadaver experiment was large. The simulation result of membrane element bending test was good. Conclusions The spring element had some limitations in force simulation. The membrane element had higher biofidelity and could reflect the biomechanical response of the ligaments.
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Objective To screen out the cytokines relating to cardiac insufficiency caused by au-toantibodies against the second extracellular loop of the β1-adrenoceptor(β1-AA) using cytokine chip tech-nique, and to analyze the changes in signaling pathways. Methods Blood samples were collected from 67 patients with coronary artery disease(CAD) and 42 healthy subjects. ELISA was performed to detect β1-AA in plasma. BALB/c mice were passively immunized with the monoclonal antibodies against β1-AA (β1-AA mAb). Dynamic changes in mouse cardiac structure and functions were detected by heart ultrasound. Hema-toxylin and eosin (HE) and Masson staining were used to observe morphological changes in heart tissues.Cytokine chip technique was used to screen out the cytokines causing myocardial injury. Gene Ontology (GO) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment analysis were used to classify the differentially expressed cytokines. Results Patients with CAD showed increased titer and posi-tive rate of β1-AA as compared with healthy subjects(P<0.001). The mouse model of heart injury was in-duced by β1-AA at the 8th week after immunization. A total of 37 differentially expressed cytokines were found in the model group,of which 11 cytokines were up-regulated and 26 cytokines were down-regulate as compared with those in the mouse control group. The level of CXCL16 was significantly increased in β1-AA-positive mice. GO analysis showed that CXCL16 was mainly involved in life processes including the positive regulation of cell death, migration, locomotion and cellular component movement. KEGG pathway enrich-ment analysis showed CXCL16 was significantly enriched in the pathway of cytokine-cytokine receptor inter-action and chemokine signaling pathway. ELISA showed that compared with β1-AA-negative patients, CXCL16 level was significantly increased in β1-AA-positive patients (P<0.01). A positive correlation was found between β1-AA and CXCL16 (P<0.01,r=0.43). Conclusion CXCL16 may play a critical role in the development of cardiac insufficiency induced by β1-AA.
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The pediatric cadaver impact experiments were reconstructed using the validated finite element(FE) models of the 3-year-old and 6-year-old children. The effect of parameters, such as hammer size, material parameters and thorax anatomical structure characteristics, on the impact mechanical responses of 3-year-old and 6-year-old pediatric thorax was discussed by designing reasonable finite element simulation experiments. The research results showed that the variation of thorax contact peak force for 3-year-old group was far larger than that of 6-year-old group when the child was impacted by hammers with different size, which meant that 3-year-old child was more sensitive to hammer size. The mechanical properties of thoracic organs had little influence on the thorax injury because of the small difference between 3-year-old and 6-year-old child in this research. During the impact, rib deformation led to different impact location and deformation of internal organs because the 3-year-old and 6-year-old children had different geometrical anatomical structures, such as different size of internal organs. Therefore, the injury of internal organs in the two groups was obviously different. It is of great significance to develop children finite element models with high biofidelity according to its real anatomical structures.
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Objective To explore the effect of cigarette smoke exposure on testis structure and nitric oxide (NO) level in testis of rats.Methods A total of 160 adult male SD rats were divided into control group and low,medium,high dose groups.The smoke-exposed rats were respectively exposed to the smog for the periods of 2,4,6,8 and 12 weeks,10 rats in each group.The smoke-exposed rats were exposed to cigarette smoke for 0.5 h per day.The testicular tissue structure was observed and the body mass and the NO level of testis were measured.Results Compared with the control group and low dose group,the body mass of the rats was significantly lower in the medium and high dose groups exposed for 4,6,8,12 weeks (P<0.05).Compared with the medium dose groups,the body mass of the rats was significantly lower in the high dose group exposed for 8 weeks and 12 weeks (P<0.05).And with the increase of exposure dose,the reducing was even more obvious.Compared with the control group and low and medium dose groups,NO level in testis of rats was significantly increased in the high dose groups exposed for 2,4,6,8 weeks (P<0.05).Compared with the control group,NO level in testis of rats was significantly increased in the medium dose groups exposed for 8 weeks (P<0.05).Compared with the control group,NO level in testis of rats was significantly increased in the low,medium and high dose groups exposed for 12 weeks (P<0.05);and compared with the low dose group,NO level in testis of rats was significantly increased in the medium and high dose groups(P<0.05).Conclusion Cigarette smoke exposure may have impacts on testis tissue and lead to the increase of NO level in testis of male rats.
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Objective To develop the finite element model of six-year-old child occupant lower extremity with higher biofidelity and validate the model of knee joints,as well as analyze the biomechanical responses of growth plate under frontal impact load and injury mechanisms of the knee joint by using this model.Methods The sixyear-old child occupant lower extremity with growth plate was modeled based on children's anatomy and CT images,and corresponding material properties of the lower extremity model were assigned.The model was validated according to biomechanical experiments by Kerrigan et aL and Haut et aL and then was used to analyze the injury results of growth plate with different material properties.Results The model validation was qualified by comparing the curves from the experimental and simulation results.The growth plates at knee regions could change injury patterns of the child occupant lower extremity fracture.The material properties of growth plate could affect threshold of axial damage of the femur as well as relative position of the fracture.Conclusions The validated model can be used for related study and application on biomechanical responses and injury mechanisms of sixyear-old child occupant lower extremities.
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Objective@#To explore an optimal method for granulocyte cell production from umbilical cord blood mononuclear cells.@*Methods@#Erythrocytes were precipitated by hydroxyethyl starch. Mononuclear cells were isolated through Ficoll density gradient centrifugation. Different media, additives and cultivation model were chosen for granulocyte induction. Cell morphology was observed by microscopy, and cell phenotype was detected by flow cytometry. The CD18 expression of granulocytes was tested by immunofluorescence assay, and phagocytosis test was executed as well.@*Results@#Compared to fetal bovine serum (FBS) treatment group, cell viability, counts and differentiation rate of granulocytes induced by X-VIVOTM 15 combined with TPO, SCF, G-CSF but without FBS were superior. And X-VIVOTM15 medium was better than SCGM medium at effectiveness and cost. Using two-stage mode of hematopoietic stem cell expansion followed by granulocyte induction with X-VIVOTM15 combining TPO, SCF and G-CSF, cell proliferation was nearly 132 times at day 21. Flow cytometry showed that the differentiation was lagged in 2-stage mode than in direct induction mode, CD15 expression was (69.60± 1.06) % vs (97.73±0.39) %; Wright-Giemsa staining demonstrated mature granulocytes; immunofluorescence showed the expression of lysosomal proteins CD18. A strong phagocytic function of mature granulocytes was demonstrated by phagotrophic efficiency of (51.43±0.05) %. And granulocyte had chemotaxis ability under the role of chemotactic factor IL-8.@*Conclusion@#Optimized culture media and cultivation mode are achieved for functional granulocytes induction in vitro.
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Inflammatory bowel disease is a chronic inflammation of the intestinal tract ,which comprises two primary forms of Crohn's disease(CD) and ulcerative colitis (UC) .Decades of studies have revealed that environmental factors ,suscepti-bility genes ,and gut microbiota are considered as the major determinants for the induction of IBD .The combination of factors has made IBD as an appropriate and a high-priority platform for studying host-microbiome interactions .More recently ,profiling studies of the intestinal microbe have associated pathogenesis of IBD with characteristic alterations in the composition of the in-testinal microbiota ,reinforcing the viewpoint that IBD results from the altered interplays between the host and intestinal mi-crobe .the studies of the gut flora in IBD were reviewed andthe multiple effects of intestinal microbiota-dysfunction on the IBD were described .The progress of intestinal microbiota alterations with different therapeutic methods in animal models and clinic trials were provided .
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OBJECTIVE:To evaluate the rationality and validity of chemical medicine tablet production equipment cleaning pro-cedure. METHODS:Among several chemical medicines prepared by similar production technology as Metoprolol succinate sus-tained-release tablets,Captopril tablets,Isosorbide mononitrate tablet and Metformin hydrochloride tablet,Metoprolol succinate sus-tained-release tablets had strongest toxicity and were included in validation test. The production equipment was cleaned and disinfect-ed according to cleaning procedure. The point which was most difficult to clean could be wiped and sampled by using the cotton swab method. The detection limit and the limit of quantitation of the residue limits were verified as well as the recovery rate of wip-ing,in order to evaluate whether the results meet the requirements. RESULTS:The cotton swab method is adopted to wipe sample and detect the point which is most difficult to clean. The visible foreign body has not been found in each sampling point. The amount of residual drug is <29.75 μg/cotton bud,and microbial limits are <50 CFU/cotton bud,indicating test items are in line with the standard. CONCLUSIONS:The cleaning method can effectively clean the production equipment,and can effectively pre-vent product contamination and cross contamination to ensure the quality,efficacy and safety of the next batch of products.