In vitro degradation behavior of Mg-Zn-Ca alloys / 中国组织工程研究

BACKGROUND:Due to the complex physiological environment of the human body,a wide variety of simulated physiological fluids have been chosen for the current degradation experiments.Therefore,it is of great interest to analyze the degradation behavior of Mg-Zn-Ca alloys in different simulated body fluid environments. OBJECTIVE:To investigate the degradation process and property changes of Mg-Zn-Ca alloy in different simulated body fluids,and to clarify the influence of Ca content and simulated body fluid type on the alloy. METHODS:Mg-Zn-Ca alloys with calcium content of 0.2%,0.5%and 1%were prepared by melting extrusion molding process and were named Mg-Zn-0.2Ca,Mg-Zn-0.5Ca and Mg-Zn-1Ca alloys in turn,with Mg-Zn alloy as the control.The prepared alloys were placed into three simulated body liquids(physiological saline,PBS and Hank's solution),and the morphology,compositional changes,mass loss,pH value and mechanical properties were characterized and analyzed during the degradation. RESULTS AND CONCLUSION:(1)With the extension of degradation time,a large number of nanoscale lamellae and columnar structures were generated on the surface of the degraded alloy,and the main components were MgO and Mg(OH)2.The degradation rate of the four kinds of alloys in physiological saline was the fastest,and that in Hank's solution was the slowest.The degradation rate in physiological saline was as follows:Mg-Zn<Mg-Zn-0.2Ca<Mg-Zn-0.5Ca<Mg-Zn-1Ca.The degradation rate in PBS and Hank's solution was as follows:Mg-Zn<Mg-Zn-0.2Ca ≈ Mg-Zn-0.5Ca<Mg-Zn-1Ca.(2)With the extension of degradation time,all four kinds of alloys had a certain mass loss.The degradation in physiological saline was the fastest;the degradation in Hank's solution and PBS was slow,and in the same simulated body fluid,with the increase of calcium content in the alloy,the corrosion rate of the alloy was obviously accelerated.(3)The pH rise was mainly concentrated in 1 day and slowed down after that,and the pH change was the largest in PBS.In the same simulated body fluid,with the increase of calcium content in the alloy,the pH value in the degradation environment increased significantly.(4)In the initial state,the elastic modulus of all Mg-Zn-Ca alloys was higher than that of Mg-Zn alloys.After being placed in simulated body fluids,the elastic modulus of the four alloys decreased with the extension of degradation time,and the decrease was most obvious in physiological saline.(5)In conclusion,a small amount of Ca addition improved the mechanical properties of Mg-Zn-Ca alloy.A small amount of Ca does not accelerate the degradation rate of the alloy,but excessive Ca accelerates the degradation rate of the alloy.During the degradation,the effect of physiological saline simulated body fluid on the mechanical strength of the alloy was the most significant.

Finite element analysis of osteoporosis in proximal femur after cannulated screw fixation for femoral neck fracture / 中国组织工程研究

BACKGROUND:After the internal fixation of cannulated screws in femoral neck fractures,because the affected limb is often unable to bear weight in the short term and the implants with high stiffness have a stress shielding effect on the fracture end,it is easy to cause osteoporosis of the affected limb and changes in the biomechanical distribution of the proximal femur,the incidence of osteonecrosis of the femoral head is high after surgery.At present,few studies have been conducted on the biomechanical effects of osteoporosis at the proximal end of the femur occurring after femoral neck fracture surgery on femoral neck fracture treated with cannulated screws. OBJECTIVE:Using finite element analysis,to investigate the biomechanical effects of osteoporosis occurring after femoral neck fracture surgery on femoral neck fracture treated with cannulated screws and explore the role of biomechanical factors in osteonecrosis of the femoral head. METHODS:Based on the obtained CT scan data of the femur in a patient with a femoral neck fracture,a proximal femoral model for internal fixation for femoral neck fracture was established by Mimics 19.0,3-Matic,UG 11.0,Hypermesh 14.0,and Abaqus software.One finite element model of the proximal femur without osteoporosis and three finite element models of the proximal femur with osteoporosis were analyzed using Abaqus software.The stress,contact pressure,displacement peak and cloud map under different components of the four models were measured and analyzed,and the internal stress changes and distribution of the femoral head were compared and analyzed. RESULTS AND CONCLUSION:The stresses and contact pressures of the femoral head and lower anterior cannulated screws varied more with the degree of osteoporosis.The peak displacement of the four models increased slowly with the degree of osteoporosis.By one-way analysis of variance,there was no significant effect of the degree of osteoporosis on the peak stress,contact pressure,and displacement of the different components.The internal stress distribution of the femoral head changed with the degree of osteoporosis.Changes in the biomechanical environment of the proximal femur have an important impact on osteonecrosis of the femoral head.

Biomechanical response of postural kyphosis under the action of bending moments / 中国组织工程研究

BACKGROUND:Most of the biomechanical studies on kyphosis have focused on trunk muscle strength and sagittal plane balance,and little has been reported on the biomechanical response within the spine during kyphosis. OBJECTIVE:To investigate the biomechanical response of the spine during postural kyphosis by simulating the process of postural kyphosis. METHODS:A three-dimensional finite element model of the normal thoracolumbar segment(T1-S1 segment)was established by using the finite element method.10 groups of pure bending loads from 1.15-11.52 N·m were applied using a three-point force system on T1,T6,and T12 vertebrae to simulate the process of postural kyphosis in normal humans.The relationship between the loads and Cobb angle and the biomechanical responses of vertebrae,ribs,and intervertebral discs were analyzed. RESULTS AND CONCLUSION:(1)During postural kyphosis,the Cobb angle size of T1-T12 segments was linearly related to the load size.(2)The maximum stresses on the vertebrae,ribs,and intervertebral discs increased with increasing load.(3)Under the action of 11.52 N·m moment,the maximum stresses on the vertebral body,ribs,and intervertebral disc were found in the front of the T6 vertebral body,the rib head of the 10th pair of ribs,and the right posterior side of the intervertebral disc of the T5-T6 segments.(4)The results of this study suggest that postural kyphosis leads to increased stress on the vertebrae,ribs,and discs,with the most significant increase in stress on the anterior side of the T6 vertebrae,at the rib head of the 10th pair of ribs,and on the anterior side of the disc at the T5-T6 segment,as well as on the posterior side,which may increase the risk of injury to the vertebrae,ribs,and discs,which provides a biomechanical basis for the design of kyphosis orthoses.

Possible mechanisms of multi-pathway biological effects of laser therapy for knee osteoarthritis / 中国组织工程研究

BACKGROUND:Laser therapy is a non-invasive and painless treatment that is considered to be an effective method suitable for the treatment of osteoarthritis due to its simplicity and non-invasive nature.Currently,the mechanism of action of laser therapy is unclear and the results of studies on its clinical application are controversial. OBJECTIVE:To review and summarize the latest research progress of laser therapy on chondrocytes,animal experiments and clinical efficacy,and to explore the possible mechanism of laser-mediated multi-pathway biological effects,so as to provide a theoretical basis for further research on the laser treatment of osteoarthritis of the knee joint. METHODS:A literature search was performed in CNKI,WanFang Data,VIP and PubMed databases for relevant literature published from 2018 to 2023,with"laser therapy,low level laser therapy,high level laser therapy,photobiomodulation,knee osteoarthritis,chondrocytes"as the search terms in Chinese and English,respectively.Together with 14 articles searched manually,70 articles were finally included for review. RESULTS AND CONCLUSION:Laser therapy in the treatment of knee osteoarthritis is mainly categorized into two types:low-level laser therapy and high-level laser therapy.Differences in laser parameters and treatment protocols have a direct impact on laser efficacy.When appropriate parameters are used,low-level lasers show positive effects in cellular experiments,animal models,and clinical efficacy.High-level lasers have been less studied in the treatment of knee osteoarthritis,but some preliminary clinical studies have shown positive results.Cell experiments have shown that low-level laser promotes chondrocyte proliferation and cartilage matrix synthesis,thereby reducing inflammatory response.Animal experiments have shown that low-level laser can reduce the release of pro-inflammatory factors,promote cartilage matrix synthesis,inhibit matrix degradation,and effectively improve the repair process of cartilage tissue.Low-level laser is also able to reduce oxidative stress damage and relieve pain in knee osteoarthritis.In clinical trials,both low-and high-level laser can reduce patients'pain and improve functional activities.The combination of laser therapy and exercise therapy modalities may improve the therapeutic effect.Lasers may affect intracellular signaling and cellular functions through photobiological or thermodynamic effects.This provides direct evidence that laser promotes articular cartilage regeneration.

Matrix stiffening related lncRNA SNHG8 regulates chemosensitivity of ovarian cancer / 生物医学工程学杂志

Extracellular matrix (ECM) has been implicated in tumor progress and chemosensitivity. Ovarian cancer brings a great threat to the health of women with a significant feature of high mortality and poor prognosis. However, the potential significance of matrix stiffness in the pattern of long non-coding RNAs (lncRNAs) expression and ovarian cancer drug sensitivity is still largely unkown. Here, based on RNA-seq data of ovarian cancer cell cultured on substrates with different stiffness, we found that a great amount of lncRNAs were upregulated in stiff group, whereas SNHG8 was significantly downregulated, which was further verified in ovarian cancer cells cultured on polydimethylsiloxane (PDMS) hydrogel. Knockdown of SNHG8 led to an impaired efficiency of homologous repair, and decreased cellular sensitivity to both etoposide and cisplatin. Meanwhile, the results of the GEPIA analysis indicated that the expression of SNHG8 was significantly decreased in ovarian cancer tissues, which was negatively correlated with the overall survival of patients with ovarian cancer. In conclusion, matrix stiffening related lncRNA SNHG8 is closely related to chemosensitivity and prognosis of ovarian cancer, which might be a novel molecular marker for chemotherapy drug instruction and prognosis prediction.

Shoulder arthroscopic balance point compaction with cross suture-bridge technique for treatment of avulsion fracture of the greater tuberosity of the humerus / 中华创伤杂志

Objective:To investigate the efficacy of shoulder arthroscopic balance point compaction with cross suture-bridge technique inr the treatment of avulsion fracture of the greater tuberosity of the humerus.Methods:A retrospective case series study was conducted on 14 patients with avulsion fracture of the greater tuberosity of the humerus treated in Affiliated Xinhua Hospital of Dalian University from March 2021 to March 2022, including 8 males and 6 females; aged 30-58 years [(40.2±10.5)years]. Among them, 5 patients had fracture in the left shoulder and 9 in the right shoulder. The fracture was classified as the avulsion type according to Mutch classification. All the patients were treated with shoulder arthroscopic balance point compaction with cross suture-bridge technique. The anteroposterior X-ray of the shoulder joint was taken at 1 week, 3 months, and 6 months after surgery to evaluate fracture reduction and fixation. The operative time and intraoperative blood loss were recorded. Fracture healing was evaluated by shoulder MRI at 6 months after surgery. The visual analog score (VAS), Constant shoulder joint score, American Shoulder and Elbow Surgeons (ASES) score, and shoulder range of motion (active abduction angle, active lateral external rotation angle, and active lateral internal rotation) preoperatively, at 3, 6 months after surgery and at the last follow-up were compared. The postoperative complications were observed.Results:All the patients were followed up for 12-15 months [(12.5±0.8)months]. The operative time and intraoperative blood loss were (67.0±10.5)minutes and (20.0±3.8)ml. The anteroposterior X-ray of the shoulder joint showed good reduction and fixation at 1 week, 3 months and 6 months after surgery. MRI T1 image at 6 months after surgery showed locally evenly distributed high signal, suggesting that the fracture was healed well. The values of VAS were (3.2±0.4)points, (2.5±0.5)points, and (0.7±0.3)points at 3, 6 months after surgery and at the last follow-up, which were lower than (7.2±0.6)points preoperatively; the values of Constant joint shoulder score were (53.2±5.3)points, (81.1±4.4)points, and (92.8±5.3)points, which were higher than (42.3±7.6)points preoperatively; the values of ASES score were (55.6±3.6)points, (77.1±3.2)points, and (90.8±3.5)points, which were higher than (45.8±4.2)points preoperatively; the active abduction angles were (60.5±2.5)°, (107.8±6.6)°, and (168.5±3.5)°, which were higher than (18.3±3.3)°preoperatively; the active lateral external rotation angles were (25.8±2.5)°, (30.8±2.2)°, and (63.8±2.8)°, which were higher than (15.6±3.2)°preoperatively ( P<0.05 or 0.01). The level of active internal rotation was L 5, L 1, and T 10, which was better than S 3 before surgery. The VAS, Constant shoulder joint score, ASES score, active abduction and active external rotation were significantly improved at the last follow-up compared with those at 3, 6 months after surgery (all P<0.05), with markedly improved level of active internal rotation. No major complications such as infection, instability of the shoulder joint or acromial impingement were found after surgery. Conclusion:Shoulder arthroscopic balance point compaction with cross suture-bridge technique for the treatment of avulsion fracture of the greater tuberosity of the humerus has advantages of decreased intraoperative blood loss, good reduction and healing, shoulder pain relief, early restoration of shoulder function and mobility, and few complications.

Bionic optic nerve based on perovskite (CsPbBr 3) quantum-dots / 生物医学工程学杂志

The bionic optic nerve can mimic human visual physiology and is a future treatment for visual disorders. Photosynaptic devices could respond to light stimuli and mimic normal optic nerve function. By modifying (Poly(3,4-ethylenedioxythio-phene):poly (styrenesulfonate)) active layers with all-inorganic perovskite quantum dots, with an aqueous solution as the dielectric layer in this paper, we developed a photosynaptic device based on an organic electrochemical transistor (OECT). The optical switching response time of OECT was 3.7 s. To improve the optical response of the device, a 365 nm, 300 mW·cm -2 UV light source was used. Basic synaptic behaviors such as postsynaptic currents (0.225 mA) at a light pulse duration of 4 s and double pulse facilitation at a light pulse duration of 1 s and pulse interval of 1 s were simulated. By changing the way light stimulates, for example, by adjusting the intensity of the light pulses from 180 to 540 mW·cm -2, the duration from 1 to 20 s, and the number of light pulses from 1 to 20, the postsynaptic currents were increased by 0.350 mA, 0.420 mA, and 0.466 mA, respectively. As such, we realized the effective shift from short-term synaptic plasticity (100 s recovery of initial value) to long-term synaptic plasticity (84.3% of 250 s decay maximum). This optical synapse has a high potential for simulating the human optic nerve.

Research progress of chondrocyte mechanotransduction mediated by TRPV4 and PIEZOs / 生物医学工程学杂志

Mechanical signal transduction are crucial for chondrocyte in response to mechanical cues during the growth, development and osteoarthritis (OA) of articular cartilage. Extracellular matrix (ECM) turnover regulates the matrix mechanical microenvironment of chondrocytes. Thus, understanding the mechanotransduction mechanisms during chondrocyte sensing the matrix mechanical microenvironment can develop effective targeted therapy for OA. In recent decades, growing evidences are rapidly advancing our understanding of the mechanical force-dependent cartilage remodeling and injury responses mediated by TRPV4 and PIEZOs. In this review, we highlighted the mechanosensing mechanism mediated by TRPV4 and PIEZOs during chondrocytes sensing mechanical microenvironment of the ECM. Additionally, the latest progress in the regulation of OA by inflammatory signals mediated by TRPV4 and PIEZOs was also introduced. These recent insights provide the potential mechanotheraputic strategies to target these channels and prevent cartilage degeneration associated with OA. This review will shed light on the pathogenesis of articular cartilage, searching clinical targeted therapies, and designing cell-induced biomaterials.

The Effect of Ankle Brace on Biomechanics of the Lower Extremity During Landing: A Systematic Review and Meta Analysis / 医用生物力学

Objective To examine the effects of ankle brace on biomechanics of the lower extremity during landing, so as to provide a theoretic support to choose ankle brace for people with different sports levels. Methods The key words (ankle brace OR ankle braces OR ankle bracing OR ankle support) AND (landing OR land OR jump OR hopped OR hopping) AND (biomechanics OR kinematics OR kinetics OR electromyography OR neuromuscular) in Chinese and English were searched from different electronic databases (CNKI, Web of Science, EBSCO, PubMed and other databases), for a period of Jan. 2000 to Dec. 2020. Cochrane was used to evaluate the quality of eligible studies. For meta analysis, subgroup analysis was used to assess the impact of ankle braces on ankle biomechanics.Results Thirteen studies with a total of 222 participants were included for mata analysis in this study. The semi-rigid ankle brace reduced the peak of ankle inversion by 25.8% compared with the elastic ankle brace (SMD=-0.562, P<0.001). Moreover, the elastic ankle brace reduced ankle plant flexion during landing among athletes (SMD=-3.42, P=-0.021). As for collagiate students, both elastic ankle and semi-rigid ankle decreased the ankle inversion (elastic ankle brace: 35.4%, SMD=-1.000, P=-0.013; semi-rigid ankle brace: 31.11%, SMD=-0.881, P<0.001) and ankle plant flexion (elastic ankle brace:23.30%, SMD=-1.381, P<0.001;semi-rigid ankle brace: 36.33%, SMD=-1.605, P<0.001).Conclusions Both ankle braces can prevent ankle sprain for athletes (basketball, volleyball, running) who experience training more than 5 years. The elastic ankle brace can limit the inversion and plantar flexion, while the semi-rigid ankle brace can merely decrease the ankle inversion. Therefore, athletes are more suitable for the elastic ankle brace. As for collegiate students without training history, both ankle brace can decrease the ankle inversion and plantar flexion. The elastic ankle brace has greater restriction on inversion, while the semi-rigid ankle brace has more restriction on plantar flexion. Therefore, the elastic ankle brace should be utilized if collegiate students have calcaneofibular ligament injury, while the semi-rigid ankle brace is more suitable for collegiate students who have a history of anterior talofibular ligament injury.

Deeper Understanding the Pathogenesis of Osteoarthritis from Matrix Viscoelasticity and Calcium Signaling / 医用生物力学

Generally, extracellular matrix (ECM) has the characteristics of viscoelasticity. In osteoarthritis (OA), catabolic processes alter the viscoelastic properties of functional pericellular matrix (PCM) of chondrocytes. Chondrocytes sense and respond to their mechanical microenvironment via an array of mechanosensitive receptors and channels that activate a complex network of downstream signaling pathways to regulate several cell processes central to OA pathology. Advances in understanding the specific mechanosignalling mechanisms in articular cartilage will promote the development of cell microenvironment construction in cartilage tissue engineering and the targeted precision therapeutics for OA. In this review, the work on the mechanism of matrix viscoelasticity regulating chondrocytes mechanotransduction by Agarwal et al. was briefly commented, and the recent advances related with their work was also discussed.

Characteristics of oral microbiota among women before conception and in third trimester: a retrospective cohort study / 中华围产医学杂志

Objective:To summarize and compare the characteristics of oral microbiota in women during the preconception period and the third trimester.Methods:This retrospective cohort study involved 55 women who were recruited in the Preconceptional Offspring Trajectory Study (PLOTS) conducted by Fudan University and followed up to the third trimester in the Maternal and Child Health Care Hospital of Jiading District of Shanghai from September 2016 to December 2019. A total of 110 unstimulated saliva samples were collected in the preconception period ( n=55) and the third trimester ( n=55). Features of oral microbiota in the samples were analyzed by 16S rRNA gene-based sequencing. Moreover, the related factors were also analyzed. Paired t test or Wilcoxon matched-pairs signed-ranks test were used to analyze the differences in α-diversity during preconception and the third trimester; t test, analysis of variance (ANOVA), Kruskal-Wallis test and Mann-Whitney U test for comparison between groups with different characteristics and permutational multivariate analysis of variance (PerMANOVA) for β-diversity were used; Linear discriminant analysis (LDA) effect size (LEfSe 1.0) was used to identify the iconic oral flora. Results:(1) The Ace index of oral microbiota was significantly lower in the third trimester than that in the preconception period [661.14(578.15-752.85) vs 730.64 (632.40-911.00), T=1 077.00, P=0.010]. There was also a significance difference in β-diversity ( F=12.539, R2=0.104, P=0.001). Some species such as Saccharibacteria_TM7_G3, Prevotella_7, Absconditabacteria_SR1_G1, Porphyromonas, Ruminococcaceae_UCG_014, Prevotella, Peptostreptococcus, Prevotella_2, Alloprevotella, Parvimonas, Solobacterium and Eubacterium_nodatum_group in saliva were statistically more abundant in the third trimester than those in the preconception period (all P<0.05). (2) The third-trimester Shannon index was lower among those with lower income [5.44 (5.08-5.77) vs 5.75 (5.44-6.12), U=219.00, P=0.029] and those with gargle habit after meal or dessert [5.36 (4.91-5.48) vs 5.72 (5.44-6.05), U=374.00, P=0.046]. Conclusions:The features of oral microbiota vary in women during the preconception period and the third trimester. There is a significant increase in the abundance of oral pathogenic and opportunistic bacteria in the third trimester.

Effects of Gender and Maneuvers on ACL Injury Risk Factors for Volleyball Players / 医用生物力学

Objective To study the effect of gender and maneuvers on anterior cruciate ligament (ACL) injury risk factors for volleyball players. Methods Sports biomechanics data of volleyball players during stop-jump, drop landing and sidestep cutting were collected. The ACL injury rate and biomechanical parameters of simulated injured jumps were obtained with Monte Carlo simulation. The influence of gender and maneuvers on ACL injury risk factors was validated by 2×3 mixed designed two-way ANOVA. Results Sidestep cutting was the highest risk maneuver of ACL injury for both genders (P＜0.001). Compared with male players, female players had a greater risk of ACL injury during sidestep cutting and stop-jump (P＜0.001), while male players were more prone to have ACL injury than female players during drop landing (P＜0.001). The risk factors of ACL injury obtained by simulation were significantly influenced by gender and maneuvers (P＜0.001). Conclusions Male players were more likely to increase ACL load due to smaller knee flexion, forward leg tilt and heel landing than female players during sidestep cutting, while female players owned larger ground reaction force (GRF) and knee extension moment. Smaller knee flexion angle during stop jump was the major risk factor for both genders, however more characteristics contributed to the males. Female players with large GRF, knee valgus and extension moment, and heel-landing were likely to have ACL injury, while the small knee flexion angle was the key risk factor for male players. The results can provide evidences for evaluation of volleyball players’ ACL injury risk, individualized injury prevention protocols, and clinical treatment and rehabilitation directions.

Influences of Cell-ECM Adhesion on Migration of Tumor Cells Regulated by ECM Stiffness: A Model Study / 医用生物力学

Objective To study the influence of cell-extracellular matrix (ECM) adhesion on migration of tumor cells regulated by ECM stiffness. Methods The cellular Potts model (CPM) was established to simulate tumor cell growth and cellular immune feedback system. The effects from mechanical behavior of cells on cell-ECM adhesion were observed, and the migration of tumor cells under different ECM was analyzed. Results The ECM stiffness could influence the migration rate of tumor cells. The change of ECM stiffness regulated the adhesion force between cells and ECM, and the change of adhesion force would influence the migration rate of cells. Conclusions The migration and distribution patterns of cells are closely related to the adhesion and stiffness of ECM. The increase in ECM stiffness can effectively promote the migration rate of tumor cells, and the further increase in ECM stiffness inhibits the migration of tumor cells. These findings may further reveal dynamic changes of ECM, adhesion and mechanical performance of tumor cell migration.

Risk factors of necrotizing enterocolitis after surgery for intestinal atresia / 中国新生儿科杂志

Objective:To study the risk factors of necrotizing enterocolitis (NEC) after surgery for intestinal atresia.Method:From August 2013 to June 2020, children with intestinal atresia receiving surgery in our hospital were retrospectively reviewed. The patients were assigned into NEC group and non-NEC group according to the occurrence of postoperative NEC. Demographic data and clinical characteristics were summarized and the risk factors for postoperative NEC were analyzed using Logistic regression analysis method.Result:A total of 96 infants were enrolled and NEC occurred in 13 patients (13.5%) after surgery for intestinal atresia. Compared with the non-NEC group, the NEC group were diagnosed of intestinal atresia [4.0(1.5,6.0)d vs. 1.4(0,2.0)d, P<0.001] and received surgery [4.8(2.0,7.0)d vs. 3.1(1.0,4.0)d, P=0.034] at later ages. The incidences of complex intestinal atresia [76.9%(10/13) vs. 44.6%(37/83), P=0.030] and blood transfusion [46.2%(6/13) vs. 13.3%(11/83), P=0.007] in the NEC group were higher than the non-NEC group. Logistic regression analysis showed that the age of initial diagnosis of intestinal atresia ( OR=3.346, 95% CI 1.493~7.500, P=0.003), complex intestinal atresia ( OR=9.052, 95% CI 1.119~73.209, P=0.039) and blood transfusion ( OR=6.835, 95% CI 1.399~33.380, P=0.018) were independent risk factors for postoperative NEC. Conclusion:Patients with delayed diagnosis of intestinal atresia, complex intestinal atresia and blood transfusion within 48 hours after surgery should be monitored for the occurrence of postoperative NEC.

The effect of parasitic ions on riboflavin permeability and cross-linking effectiveness in iontophoresis-assisted scleral cross-linking / 生物医学工程学杂志

The effect of parasitic ions on the results of ultraviolet A (UVA) cross-linking in iontophoresis was still not clear. In this work, the porcine sclera was cross-linked by riboflavin lactate Ringer's solution (group A) and riboflavin normal saline (group B)

Finite element analysis of the effect of local posterior sclera collagen cross-linking on eyeball shape / 生物医学工程学杂志

China is the country with high incidence of high myopia in the world. High myopia can cause severe vision impairment. So far, there is no effective treatment for high myopia in clinic. Scleral collagen cross-linking surgery has been proven to be effective in preventing animal eye axial elongation

Finite element analysis of determining corneal biomechanical properties in vivo based on Corvis ST / 生物医学工程学杂志

The decrease of corneal stiffness is the key factor leading to keratoconus, and the corneal collagen fiber stiffness and fiber dispersion are closely related to the corneal biomechanical properties. In this paper, a finite element model of human cornea based on corneal microstructure, namely collagen fiber, was established before and after laser assisted in situ keratomileusis (LASIK). By simulating the Corvis ST process and comparing with the actual clinical results, the hyperelastic constitutive parameters and corneal collagen fiber stiffness modulus of the corneal material were determined before and after refractive surgery. After LASIK, the corneal collagen fiber stiffness modulus increased significantly, and was highly correlated with central corneal thickness (CCT). The predictive relationship between the corneal collagen fiber stiffness modulus and the corresponding CCT before and after surgery was: = exp(9.14 - 0.009CCT ), = exp(8.82 - 0.008CCT ). According to the results of this study, the central corneal thickness of the patient can be used to estimate the preoperative and postoperative collagen fiber stiffness modulus, and then a personalized corneal model that is more consistent with the actual situation of the patient can be established, providing a theoretical reference for more accurately predicting the safe surgical cutting amount of the cornea.

The Trans-Scale Conduction Behavior of Fluid Stimulation in Loaded Bone / 医用生物力学

Objective To investigate the conduction behavior of fluid flow induced by physiological loads at different scales of bone. Method sThe multiscale bone models were established by using the COMSOL Multiphysics software, and the fluid behaviors were investigated at macro-, meso- and micro-scale. Results At macro-meso scale，the distribution of pore pressure and fluid velocity of osteon near the periosteum and endoosteum were different from that in other parts. Due to the different structure and material parameters at different layers, the loading and fluid pressure caused different biomechanical responses in the process of transferring from macro-scale to micro-scale. Conclusions The multi-scale layered modeling of bone structure-osteon-lacunae-bone canaliculi was established, which provided the theoretical reference for deeper understanding of fluid stimulation and mechanotransduction.

Effects of LASIK on Biomechanical Properties of Human Cornea / 医用生物力学

Objective To study the changes in biomechanical properties of human cornea after laser in situ keratomileusis (LASIK) and predict corneal stiffness after the LASIK surgery. Methods According to the measurement results from corneal visualization scheimpflug technology (Corvis ST), the corneal tangent stiffness coefficient (STSC) and energy absorbed area (Aabsorbed) were calculated. The change patterns of corneal stiffness and viscosity after refractive surgery were analyzed. Results The difference of corneal STSC and Aabsorbed before and after LASIK had a statistical significance (P<0.05). The obtained formula for predicting corneal stiffness after refractive surgery was: Sbefore surgery =1.055bIOPbefore surgery + 0.015CCTbefore surgery，Safter surgery =0.937Sbefore surgery +0.019CCTafter surgery. Conclusions LASIK surgery not only changes corneal thickness, but also reduces corneal stiffness and viscosity. Prediction of corneal stiffness after surgery can provide guidance for the design of clinical surgery and improve the safety of surgery.

Biomechanical Study on Segmental Compression of Rabbit Spine / 医用生物力学

Objective To investigate the pathological mechanism of spinal injury by axial compression experiment on animal spine, so as to provide references for the treatment, prevention and research of spinal injury. Methods The biomechanical study of rabbit spine segments was performed by axial segment compression experiment. The compression process was recorded and strain analysis was performed by digital image correlation (DIC) technology. Results From the top to the bottom of the spine, the ultimate load and bearing capacity of the segment increased continuously; the average limit load of the corresponding single vertebral body was significantly larger than the segment; the strain of the intervertebral disc in the horizontal and vertical directions was significantly larger than that of the upper and lower vertebral bodies. Conclusions In the process of spine compression, the bearing capacity of the intervertebral disc should be taken into account and the injury of spinal segments is mainly manifested as abnormality of the intervertebral disc. The research findings contribute to the prevention and treatment of spinal compression fractures, as well as the design of related therapeutic instruments and assistive devices.