Finite element analysis of different reconstruction methods of coracoclavicular ligament for acromioclavicular joint dislocation / 中国骨伤

OBJECTIVE@#This study aims to examine the biomechanical effects of different reconstruction methods, including single-bundle, double-bundle anatomical reconstruction, and double-bundle truly anatomical reconstruction of the coracoclavicular ligament on the acromioclavicular joint using finite element analysis, to provide a theoretical basis for the clinical application of truly anatomical coracoclavicular ligament reconstruction.@*METHODS@#One volunteer, aged 27 years old, with a height of 178 cm and a weight of 75 kg, was selected for CT scanning of the shoulder joint. Three-dimensional finite element models of single-bundle reconstruction, double-bundle anatomical reconstruction, and double-bundle truly anatomical reconstruction of coracoclavicular ligament were established by using Mimics17.0, Geomagic studio 2012, UG NX 10.0, HyperMesh 14.0 and ABAQUS 6.14 software. The maximum displacement of the middle point of the distal clavicle in the main loading direction and the maximum equivalent stress of the reconstruction device under different loading conditions were recorded and compared.@*RESULTS@#The maximum forward displacement and the maximum backward displacement of the middle point of the distal clavicle in the double-bundle truly anatomic reconstruction were the lowest, which were 7.76 mm and 7.27 mm respectively. When an upward load was applied, the maximum displacement of the distal clavicle midpoint in the double-beam anatomic reconstruction was the lowest, which was 5.12 mm. Applying three different loads forward, backward, and upward, the maximum equivalent stress of the reconstruction devices in the double-beam reconstruction was lower than that in the single-beam reconstruction. The maximum equivalent stress of the trapezoid ligament reconstruction device in the double-bundle truly anatomical reconstruction was lower than that in the double-bundle anatomical reconstruction, which was 73.29 MPa, but the maximum equivalent stress of the conoid ligament reconstruction device was higher than that of the double-bundle anatomical reconstruction.@*CONCLUSION@#The truly anatomical reconstruction of coracoclavicular ligament can improve the horizontal stability of acromioclavicular joint and reduce the stress of the trapezoid ligament reconstruction device. It can be a good method for the treatment of acromioclavicular joint dislocation.

The study of the protective effect and its mechanism of Edaravone to neurons with hydrogen peroxide stimulated / 中华外科杂志

<p><b>OBJECTIVES</b>To prove the protective effect of Edaravone to neurons and to study the particular mechanism.</p><p><b>METHODS</b>Neurons were collected from 18-day fetal rat brains and a culture of almost pure neurons was obtained after 14-day culture, then the cells were randomly assigned to one of the three groups: control group, hydrogen peroxide (H₂O₂)-treated group, and Edaravone-treated group. In H₂O₂-treated group, 300 µmol/L H₂O₂ was added to the medium, followed by returning to the normal culture for the presupposition of time. In Edaravone-treated group, 500 µmol/L Edaravone was prophylactically added to the medium for 30 minutes before the insult. Morphology of mitochondria was visualized by transmission electron microscopy. The rate of apoptotic cells was detected by flow cytometry analysis. The relationships between the proteins and the key proteins expressions were observed by immunoprecipitation and immunoblotting.</p><p><b>RESULTS</b>Compared to the Edaravone-treated group, mitochondria in H₂O₂-treated group displayed more vesicular matrix compartments at the same time. Percentage of apoptotic cells in H₂O₂-treated group after 0.5, 2, 6 and 12 h were 14.40% ± 1.23%, 45.50% ± 2.81%, 56.40% ± 3.53%, 62.50% ± 4.23%, which were higher than control group (F = 274.8, P < 0.01). Edaravone-treated group were 0.90% ± 0.07%, 1.10% ± 0.08%, 3.50% ± 1.90%, 12.60% ± 1.10%, which were lower than H₂O₂-treated group (F = 362.7, P < 0.01). After H₂O₂ stimulation for 0.5 h in H₂O₂-treated group, the levels of p-JNK (Thr183/Tyr185) and cytochrome c in cytosol and BAX in heavy membrane were increased significantly at 0.5 h, reaching a peak at 12 h after stimulation, In addition, the expressions of p-BAD, BAX, BAD and 14-3-3 of cytoplasm decreased, however, these changes were inhibited in the Edaravone-treated group.</p><p><b>CONCLUSIONS</b>As a free radical scavenger, the Edaravone could protect neurons by inhibiting the activity of JNK, the disassociation of BAD from 14-3-3 and the translocation of BAX from the cytosol to mitochondria.</p>

The effect of oxidative stress in myocardial cell injury in mice exposed to chronic intermittent hypoxia / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Obstructive sleep apnea syndrome (OSAS) is an important risk factor for cardiovascular diseases. Chronic intermittent hypoxia (CIH) is considered to be one of the most important causes of cardiovascular diseases in OSA patients. This repeated hypoxia and reoxygenation cycle is similar to hypoxia-reperfusion injury, which initiates oxidative stress. In this study, we observed cardiocytes injury induced by CIH and the effect of N-acetylcysteine (NAC).</p><p><b>METHODS</b>Thirty ICR mice were randomly assigned to 3 groups: control, CIH and NAC (CIH + NAC) groups. Malondialdehyde (MDA) and superoxide dismutase (SOD) of cardiocyte homogenates were measured. Serum lipids were measured by an instrument method. Serum cardiac troponin I (cTnI) was detected by enzyme-linked immunosorbent assays (ELISA). Myocardium pathological sections were observed.</p><p><b>RESULTS</b>(1) The SOD activity and MDA concentration of cardiocyte homogenates in the CIH group were significantly higher than in other groups (P < 0.005). The MDA concentration of the NAC group was lower than that of the control group (P < 0.01). (2) The serum cTnI concentration of the CIH and NAC groups was significantly higher than that of the control group (P < 0.01). (3) Serum triglyceride levels in the NAC group were lower than in the other groups (P < 0.01), while there were no significant differences in low density lipoprotein and high density lipoprotein among the three groups. (4) The degeneration of myocardium, transverse striation blurred, and fabric effusion were observed in tissue sections in the CIH and NAC groups. However, normal tissue was found in the control group.</p><p><b>CONCLUSION</b>The oxidative stress induced by CIH can injure cardiocytes and the injury effect can be partially inhibited by NAC.</p>

GIT1 promotes osteoblast migration by regulating ERK1/2 activity in focal adhesions / 中华创伤骨科杂志

Objective To study the function and mechanism of GIT1(G protein coupled receptor kinase interacting protein 1)in osteoblast migration.Methods GIT1 and ERK1/2(Extracellular Signal-regulated ki- nase 1/2)were detected in mice primary osteoblasts.The localizations of GIT1 and ERK1/2 were determined by immunofluorescence stain with or without PDGF(platelet-derived grnwth factor)stimulation.The association of GIT1 anti ERK1/2 was analyzed by co-immunoprecipitation and western blot.After stimulation,the co-localization of GIT1 and pERK1/2 in osteoblasts was detected by double-immunnfluorescence stain.The pERK1/2 localization was detected by immunofluorescence stain after GIT1RNAh adenovirus infection of osteoblasts.The role of this associa- tion was determined by wound healing assay.Results The co-immunoprecipitation results showed that GIT1 in- teracted with ERK1/2 in osteoblasts induced by PDGF and this association occurred in focal adhesions.GIT1 RNAh adenovirus significantly inhibited the pERK1/2 translocation to focal adhesions and osteoblast migration induced by PDGF.Conclusion GIT1 associates with ERK1/2 in osteoblasts,which is required for pERK1/2 translocation to focal adhesions and osteoblast migration.