BACKGROUND: The biomechanics of cervical spine is complicated. It is an important way to select the appropriate biomechanical model and research method so as to explore the diagnosis and evaluation mechanism of cervical spine injury and prognosis judgement.OBJECTIVE: To discuss the alternation of cervical biomechanics after the degeneration of cervical disc and the influence of degeneration on cervical stability.METHODS: (1) A three-dimensional finite element model of cervical spine was established from the CT scan images of cervical spine of a healthy male volunteer, Solid-Works2015, HyperMesh and ANSYS11.0. We created a cervical three-dimensional finite element model. To simulate the degenerative disc by modified the mechanical characters and height of the disc model, we observed the biomechanics of the impact on the cervical spine (the range and the stress on intervertabral disc).RESULTS AND CONCLUSION: (1) The entire model with a total of 97705 nodes and 372896 elements. Ligament and joint capsule were also constructed. Face to face contact element was used in the facet joint, with complete structure and high accuracy of measurement of spatial structure. (2) The range of motion of cervical spine increased during degeneration compared with normal cervical segments (P < 0.05). (3) Intervertebral disc degeneration caused angle increase at disc and motion segment. Osteophyte formed on vertebral edge. Intervertebral disc degeneration caused cervical instability. Simultaneously, instability increased the disc degeneration.

In this paper, combined with the finite element (FE) method and optimization theory, a strain energy criterion is used to simulate and predict the bone remodeling. The strain energy density is taken as the mechanical stimulus. The bone remodeling is described as the changes of material distribution, which can represent the process of bone remodeling. By remodeling simulation of a two-dimensional proximal femur, a three-dimensional proximal femur and bone fracture healing plastic process, we demonstrate that this criterion can produce a realistic apparent density distribution in the proximal femur, and this criterion can well illuminate the mechanism of bone fracture healing plastic process.
Adaptation, Physiological ; physiology ; Biomechanical Phenomena ; Bone Remodeling ; physiology ; Bone and Bones ; physiology ; Computer Simulation ; Femur ; physiology ; Finite Element Analysis ; Humans ; Models, Biological ; Stress, Mechanical

Objective To investigate the effects of signal transducer and activator of transcription 3 (STAT3) RNAi on the content of reactive oxygen species (ROS) and the DNA damage in glioma cells.Methods Glioma cells of the line U251 cells were cultured and transfected with STAT3 RNAi plasmid (pSilencer2.1-STAT3,STAT3 group) and pSilencer2.1-GFP (GFP control group) respectively.Part of the U251 cells were irradiated with γ-rays of 60Co as positive control group of smear phenomenon.The levels of ROS and malondialdehyde (MDA) in the cells were detected 24,48,and 72 h later by flow cytometry and fluorescence chamoluminescence analyzer,respectively.The DNA damage in the transfected U251 cells was examined by using single cell gel electrophoresis assay,and the cell cycle distribution was examined using FACS PI staining 12,24,and 36 h later.Results At 24 h after the transfection,the ROS level of the siSTAT3-transfected ceils was 8.91 times that of the control group (F = 89.296,P < 0.05),and returned to the normal level 48 h later.There were not significant differences in the MDA level of the cells 24,48,and 72 h later between the siSTAT3 group and siGFP group.Compared with the 8 Gy irradiation positive group with obvious smear phenomenon,smear phenomenon was shown in part of the ceils in the siSTAT3 group 6 h later,became less 12 h later,and disappeared completely 24 h later.Compared with the control group,lag of S stage rate was 17.22% and the lag of G2/M stage rate was 6.4% 12 h later in the siSTAT-transfected group,and the G0/G1 stage lag rate was 18.44% 24 h later,and the lag of S stage rate was 17.99% 36 h later.Conclusions Inhibition of STAT3 results in the change of oxidoreduction status in glioma cells,as well as damage and reparation of DNA.

The finite element model of the intact lumbar spine (L1-L5) was set up to study the biomechanical changes of three different pairs of the lumbar laminectomy. The three-dimensional finite elements model of L1-L5 vertebrae structure was constructed by the combination of self-compiled software and Hyper Mesh. The finite element model was compared with the experimental data in vitro. The finite element model was modified of stenosis at L3-L4 and L4-L5 with the same boundary conditions and physical loads to study the motion and loading in the annulus changes at the surgical site as a result of surgical alteration. The study suggested that the removal of posterior lumbar spinal elements for the treatment of stenosis at L3-L4 and L4-L5 produced a graded increase in motion at the surgical site, with the greatest changes occurring in flexion-extension and axial rotation and that during lateral bending the amount of resection was only slightly affected. The data showed that for flexion-extension and axial rotation the increases in motion were correlated to the extent of posterior element removal. It is necessary to retain the greatest degree of posterior lumbar structures in thorough decompression, which can further reduce the postoperative intervertebral disc, facet degeneration.
Adult ; Biomechanical Phenomena ; Computer Simulation ; Finite Element Analysis ; Humans ; Laminectomy ; methods ; Lumbar Vertebrae ; diagnostic imaging ; surgery ; Male ; Models, Biological ; Spinal Stenosis ; diagnostic imaging ; surgery ; Tomography, Spiral Computed

OBJECTIVETo study the regularity of the passive tensile of the masticatory muscles and ligaments by Twin-Block appliance under various bite reconstruction, and to provide some biomechanical references for the clinical use and improvement of Twin-Block appliance.

METHODS"Temporomandibular joint, mandible and Twin-Block appliance" model was set up by the three dimensional finite element method, and the related masticatory muscles and ligaments were added on it. Seven experimental groups were designed according to the clinical and research, the occlusal inclined plate's angles of Twin-Block appliance were 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees and 70 degrees. The passive tensile in the masticatory muscles and ligaments were analyzed by the computer.

RESULTSUnder various experimental groups, the passive tensile in the anterior deep masseter (AM), the posterior deep masseter (PM), the anterior temporalis (AT), the posterior temporalis (PT), the stylomandibular ligament and sphenomandibular ligament improved with the increased slant angles of occlusal guide. The maximum value of the passive tensile was 82.57 N, the minimum value was 0.07 N.

CONCLUSION1) In various experimental groups, AT, AM, PM, PT, stylomandibular ligament and sphenomandibular ligament are subject to passive tension force in the process of Twin-Block appliance guiding the mandibular forward and play the important role on the remodeling of the mandible. 2)All groups of occlusal inclined plate's angle are in physiologically tolerable range and can be used in clinic.

Dental Occlusion ; Humans ; Ligaments ; Mandible ; Masseter Muscle ; Masticatory Muscles ; Reconstructive Surgical Procedures ; Temporal Muscle ; Temporomandibular Joint

In this study we calculate theoretically and use FEM to simulate the effect of plate position relative to bending direction on the overall bending stiffness of the composite system plate-bone. The results show that for different bending directions the effect of the modulus of elasticity of the plate is negligible. Changing the position of a plate will often alter the stress obviously. During the operation, the steel plate should be assigned onto the tension side of the bone.
Bone Plates ; Finite Element Analysis ; Fracture Fixation, Internal ; methods ; Models, Biological ; Stainless Steel ; Stress, Mechanical ; Tensile Strength

Antibiotics are a category of chemical compounds used to treat bacterial infections and are widely applied in cultivation,animal husbandry,aquaculture,and pharmacy.Currently,residual antibiotics and their metabolites pose a potential risk of allergic reactions,bacterial resistance,and increased cancer incidence.Residual antibiotics and the resulting bacterial antibiotic resistance have been recognized as a global challenge that has attracted increasing attention.Therefore,monitoring antibiotics is a critical way to limit the ecological risks from antibiotic pollution.Accordingly,it is desirable to devise new analytical platforms to achieve efficient antibiotic detection with excellent sensitivity and specificity.Quantum dots(QDs)are regarded as an ideal material for use in the development of antibiotic detection biosensors.In this review,we characterize different types of QDs,such as silicon,chalcogenide,carbon,and other doped QDs,and summarize the trends in QD-based antibiotic detection.QD-based sensing applications are classified according to their recognition strategies,including molecularly imprinted polymers(MIPs),aptamers,and immunosensors.We discuss the advantages of QD-derived antibiotic sensors,including low cost,good sensitivity,excellent stability,and fast response,and illustrate the current challenges in this field.

DNA assembly is the core technology of synthetic biology. With the development of synthetic biology, researchers have developed different DNA assembly technologies that rely on DNA polymerase or DNA ligase, and also have developed some non-enzyme-dependent DNA assembly techniques to facilitate the automation of DNA assembly. The assembly of large fragments of DNA from a few hundred kb to Mb is mostly dependent on microbial recombination. In this paper, the three types of DNA assembly technologies, including enzyme-dependent, non-enzymatic and in vivo homologous recombination, are reviewed.
DNA ; Synthetic Biology