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.

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.

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.

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.

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.

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.

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

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)

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.

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.

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.

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.

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.

Effects of Intercellular Adhesion of Tumor on Immune Escape / 医用生物力学

Objective To study the effect of intercellular adhesion of tumor cells on immune response of human body. Methods A tumor growth-cellular immune feedback model was developed based on cellular Potts model (CPM) to simulate the progression of tumor cells and the cellular immune feedback system, and the influence of adhesion between tumor cells on the immune system was analyzed. Results Under the condition of tumor intercellular adhesion with normal intensity, tumor cells could escape when the immune system was weak and be eliminated when the immune system was strong. Under the condition of tumor intercellular adhesion with low intensity, tumor cells could escape when the immune system was weak, while exhibited behavior of oscillation and could not be eliminated when the immune system was strong. Conclusions Higher adhesion between tumor cells inhibited escape of tumor cells from the immune system, while lower adhesion between tumor cells could effectively help the tumor escape killing from the immune system. When the tumor was extremely spread, the immune system could not completely eliminate tumor cells.

Hierarchical Biomechanical Properties and Constitutive Relationships of Bone Tissues / 医用生物力学

As the main organ of the body, the load-bearing ability of bone is closely connected to its biomechanical properties. Bone is a complex hierarchical biomaterial, whose biomechanical properties are determined by its own structure and biological characteristics. Because of its mechanical adaptability, bone tissues represent different biomechanical properties under different mechanical loading. To quantify the complicated properties of bone and provide an accurate theoretical basis for clinical research, it is necessary to give insight into the biomechanical properties of bone at different levels and the constitutive relationships of bone tissues. In this review, relative researches on constitutive relationships in recent years were summarized based on its hierarchical biomechanical properties.

Establishment and Verification of Personalized Musculoskeletal Model Based on nmsBuilder and OpenSim / 医用生物力学

Objective To establish a personalized musculoskeletal multi-body dynamics model of total knee replacement (TKR) by two software nmsBuilder and OpenSim, and verify this established model by using bouncy and medthrust gait patterns. Methods Based on skeletal data from a patient, the body, skeletal landmark clouds and muscular landmark clouds were established for automatically generating reference systems and muscles. The musculoskeletal model generated by nmsBuilder was introduced into OpenSim, and inverse kinematics, static optimization and knee joint force analysis were performed successively. Finally, the model was driven by bouncy gait and medthrust gait respectively, and the results were compared with experimental measurements. Results Except for the lateral joint contact forces, the predicted magnitude and trend of knee joint contact forces by the model had a good agreement with the experimental data, and the constructed skeletal muscle multi-body dynamics model could be used for knee joint research. Conclusions The established musculoskeletal multi-body dynamics model could predict the medial, lateral and total tibiofemoral joint contact forces simultaneously by inputting the marker positions and the ground reaction forces. The research ideas of this study can provide references for designing personalized knee prostheses for TKR patient.

Hierarchical Biomechanical Properties and Constitutive Relationships of Bone Tissues / 医用生物力学

As the main organ of the body, the load-bearing ability of bone is closely connected to its biomechanical properties. Bone is a complex hierarchical biomaterial, whose biomechanical properties are determined by its own structure and biological characteristics. Because of its mechanical adaptability, bone tissues represent different biomechanical properties under different mechanical loading. To quantify the complicated properties of bone and provide an accurate theoretical basis for clinical research, it is necessary to give insight into the biomechanical properties of bone at different levels and the constitutive relationships of bone tissues. In this review, relative researches on constitutive relationships in recent years were summarized based on its hierarchical biomechanical properties.

Research progress on osteochondral tissue engineering / 生物医学工程学杂志

Osteochondral defects is a common clinical joint disease. The complexity of cartilage-bone interface and the poor self-repair capacity of cartilage are both reasons for current relatively limited clinical treatments. The introduction of tissue engineering provides a new treatment method for osteochondral repair. This paper reviews three main elements of cartilage-bone tissue engineering: seed cell source and culture method, cytokines regulation and synergistic effect, and scaffold components and type. We mainly focused on current status quo and future progress of cartilage-bone repair scaffolds. This paper provides some reference for the further development of osteochondral tissue engineering.

Experimental study on mechanical properties of the ventral and the dorsal tissues of porcine descending aorta / 生物医学工程学杂志

The mechanical properties of the aorta tissue is not only important for maintaining the cardiovascular health, but also is closely related to the development of cardiovascular diseases. There are obvious differences between the ventral and dorsal tissues of the descending aorta. However, the cause of the difference is still unclear. In this study, a biaxial tensile approach was used to determine the parameters of porcine descending aorta by analyzing the stress-strain curves. The strain energy functions Gasser-Ogden-Holzapfel was adopted to characterize the orthotropic parameters of mechanical properties. Elastic Van Gieson (EVG) and Sirius red stain were used to observe the microarchitecture of elastic and collagen fibers, respectively. Our results showed that the tissue of descending aorta had more orthotropic and higher elastic modulus in the dorsal region compared to the ventral region in the circumferential direction. No significant difference was found in hyperelastic constitutive parameters between the dorsal and ventral regions, but the angle of collagen fiber was smaller than 0.785 rad (45°) in both dorsal and ventral regions. The arrangement of fiber was inclined to be circumferential. EVG and Sirius red stain showed that in outer-middle membrane of the descending aorta, the density of elastic fibrous layer of the ventral region was higher than that of the dorsal region; the amount of collagen fibers in dorsal region was more than that of the ventral region. The results suggested that the difference of mechanical properties between the dorsal and ventral tissues in the descending aorta was related to the microstructure of the outer membrane of the aorta. In the relatively small strain range, the difference in mechanical properties between the ventral and dorsal tissues of the descending aorta can be ignored; when the strain is higher, it needs to be treated differently. The results of this study provide data for the etiology of arterial disease (such as arterial dissection) and the design of artificial blood vessel.