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Objective:To compare biomechanical stabilities between screw-plate fixation and non-cannulated screw fixation for Lisfranc ligament injury by a 3-D finite element analysis.Methods:A 3-D model of a healthy foot was developed from computed tomography images. The 1st and the 2nd dorsal tarsometatarsal ligaments and Lisfranc ligament were cut in the 3-D model of a healthy foot to establish a Lisfranc ligament injury model, in which screw-plate fixation (with 2 locking plates and 8 standard screws and one non-cannulated screw) and non-cannulated screw fixation (with 3 non-cannulated screws) for Lisfranc ligament injury were simulated respectively. Finite element analyses were carried out by Abaqus 6.14 software after loads were added in the 3-D models of screw-plate fixation and non-cannulated screw fixation for Lisfranc ligament injury. The overall stress-strain nephogram, the stress distribution and displacement of the foot bone, and the stress distribution on the internal fixation system were compared between the 2 kinds of models.Results:Under the same load, the stress of the whole screw-plate fixation was concentrated on the fixators, and the stress of the non-cannulated screws was also greater than that of the bones. In both models, the strain of the whole foot led to arch collapse, especially in the medial column. The maximum stress on the screw holes in the medial and middle columns in the screw-plate fixation model was 39.91 MPa, smaller than that in the non-cannulated screw fixation model (53.13 MPa). The relative displacement of the first metatarsal joint in the screw-plate fixation model was 8.515 × 10 -1 mm, much greater than that in the non-cannulated screw fixation model (3.893 × 10 -1 mm). Stress concentration was observed in both models. The stress of the screw-plate system was concentrated on the fibular side of the middle section of the plate used to fix the first tarsometatarsal joint, decreasing towards both ends. The maximum stress of the non-cannulated screws was located in the middle of the medial column screw for fixation of the first tarsometatarsal joint, significantly greater than those of the both ends. The maximum stress of the screw-plate system was 239.5 MPa, smaller than that of the non-cannulated screws (256.8 MPa). Conclusions:Non-cannulated screw fixation demonstrates a greater biomechanical stability for Lisfranc ligament injury than screw-plate fixation. However, the former may have a higher risk of screw breakage because it bears a greater stress.
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Life sciences are the disciplines most closely related with human beings. As experimental disciplines, life sciences develop rapidly and highly intersect in many scientific fields. Under the "double first-class" initiative, the comprehensive development-oriented talent training system has put forward an urgent need for life sciences literacy and comprehensive ability training of college students. Taking the reform of liberal education curriculum system as an opportunity, we developed a series of eight life sciences practical liberal courses for students with non-biology majors. The courses cover all sub-disciplines or directions of life sciences, and aim to foster interdisciplinary talents with life sciences knowledge and literacy, as well as practical and innovative abilities. These courses could serve as references for experimental teaching centers in colleges and universities to set up practical liberal and experimental courses.
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Humans , Biological Science Disciplines , Curriculum , Students , UniversitiesABSTRACT
The correct differentiation of oligodendrocyte precursor cells (OPCs) is essential for the myelination and remyelination processes in the central nervous system. Determining the regulatory mechanism is fundamental to the treatment of demyelinating diseases. By analyzing the RNA sequencing data of different neural cells, we found that cyclin-dependent kinase 18 (CDK18) is exclusively expressed in oligodendrocytes. In vivo studies showed that the expression level of CDK18 gradually increased along with myelin formation during development and in the remyelination phase in a lysophosphatidylcholine-induced demyelination model, and was distinctively highly expressed in oligodendrocytes. In vitro overexpression and interference experiments revealed that CDK18 directly promotes the differentiation of OPCs, without affecting their proliferation or apoptosis. Mechanistically, CDK18 activated the RAS/mitogen-activated protein kinase kinase 1/extracellular signal-regulated kinase pathway, thus promoting OPC differentiation. The results of the present study suggest that CDK18 is a promising cell-type specific target to treat demyelinating disease.
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The differentiation and maturation of oligodendrocyte precursor cells (OPCs) is essential for myelination and remyelination in the CNS. The failure of OPCs to achieve terminal differentiation in demyelinating lesions often results in unsuccessful remyelination in a variety of human demyelinating diseases. However, the molecular mechanisms controlling OPC differentiation under pathological conditions remain largely unknown. Myt1L (myelin transcription factor 1-like), mainly expressed in neurons, has been associated with intellectual disability, schizophrenia, and depression. In the present study, we found that Myt1L was expressed in oligodendrocyte lineage cells during myelination and remyelination. The expression level of Myt1L in neuron/glia antigen 2-positive (NG2) OPCs was significantly higher than that in mature CC1 oligodendrocytes. In primary cultured OPCs, overexpression of Myt1L promoted, while knockdown inhibited OPC differentiation. Moreover, Myt1L was potently involved in promoting remyelination after lysolecithin-induced demyelination in vivo. ChIP assays showed that Myt1L bound to the promoter of Olig1 and transcriptionally regulated Olig1 expression. Taken together, our findings demonstrate that Myt1L is an essential regulator of OPC differentiation, thereby supporting Myt1L as a potential therapeutic target for demyelinating diseases.
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Animals , Mice , Cell Differentiation , Physiology , Demyelinating Diseases , Lysophosphatidylcholines , Toxicity , Mice, Inbred C57BL , Nerve Tissue Proteins , Metabolism , Oligodendrocyte Precursor Cells , Cell Biology , Metabolism , Oligodendroglia , Cell Biology , Metabolism , Remyelination , Physiology , Transcription Factors , MetabolismABSTRACT
Objective To explore the best anticoagulant ratio in SD rats .To analyse the influence of insufficient blood specimens volume on coagulation tests .Methods 60 rats were divided into 2 groups.According to the method of vacuum blood, collect abdominal aortic blood after fasting 12 hours.The first group 20 rats were used only for routine blood test.Fully automatic hematology analyzer detected hematocrit and platelet .The second group 40 rats were used for coagulation test .Every rat was collected 2 blood specimens with different anticoagulant ratio [ the proportion of sodium citrate anticoagulation and the whole blood (vlume∶volume)]1∶9(the control group)and 1∶5( the experimental group),1∶8( the experimental group) and 1∶7( the experimental group).Get plasma without platelet through centrifugation.Fully automatic blood coagulation analyzer detected prothrombin time , activated partial thromboplatin time , thrombin time and Fibrinogen.Results HCT (%) and PLT (x 109/L) in SD rats were respectively 41.7 ±2.9 and 1114 ±173.As anticoagulant ratio was increased ,PT, APTT and TT were extended and FIB was decreased .Compared with the control group ,these PT,APTT,TT,FIB four results of 1∶8 group were not statistically different , of 1∶5 group were statistically different, these PT,APTT,FIB three results of 1∶7 group were not statistically different , TT of 1∶7 group was statistically different.Conclusions The detection of coagulation project coagulation test results were affected by the proportion of anticoagulant and blood .1∶9 was the best anticoagulant ratio in SD rats , 1∶8 can also.Rat had its unique physiological characteristics .The results could provide reference for the evaluation of rats .
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10.3969/j.issn.2095-4344.2013.26.022
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BACKGROUND: Defatting is to reduce the special cell surface antigens by clearing fat and lipoprotein, so as to decrease immunological rejection, improve the biocompatibility of allograft bone, and increase osteogenic potential. However, the effect of defatting on biomechanical performance of bone remains controversial.OBJECTIVE: To explore the influence of defatting on the biomechanics of bovine cortical bone samples.DESIGN, TIME AND SETTING: Randomized, self-controlled observation was performed in Futian People's Hospital of Guangdong Medical College between 2006 and 2008.MATERIALS: Eight pairs of healthy adult bovine femora were used. Bone blocks, 50 mm long and 10 mm wide, were selected from each pair of femora, and burnished into 24 pairs of 7 mm×7 mm×40 mm rectangular bovine cortical bone samples.METHODS: The 24 pairs of cortical bone samples were randomly divided into two groups (n=12). One of each pair was selected as test group sample, and the other as control group sample. The samples of test group were defatted In 500 mL chloroform and methanol mixture (1:1) for 24 hours, while control samples were immerged in deionized water for 24 hours. Six samples from each group were selected for axial compressive test and three-point bending test.MAIN OUTCOME MEASURES: Load and deflection of every sample.RESULTS: Axial compressive test showed that the maximum load and the maximum strain of defatted samples were significantly decreased compared with control group, but the fragility and elastic modulus were increased (P < 0.05). In three-point bending test, the maximum load and the maximum stress of defatted sampled were significantly decreased, the maximum deflection was decreased, and the elastic modulus was increased (P < 0.05).CONCLUSION: The mechanical strength of cortical bone decreased but the fragility increased after defatting.
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Objective To observe the application and efficacy of dynamic condylar screw (DCS) in treating intertrochanteric fractures of the femur and discuss the fixation principle, feasibility, advanta-ges and related issues. Methods A retrospective analysis was done on 23 patients with intertrochanter-ic fractures of the femur treated with DCS from January 2000 to December 2006. Of all, there were 10 elderly patients with different levels of various kinds of internal diseases and 13 young patients injuried by high-energy such as traffic accidents. According to Boyd' s classfication, there was one patient with type Ⅰ fracture, five with type Ⅱ , nine with type Ⅲ and eight with type Ⅳ. After a detailed pre-operative physical examination and targeted treatment, DCS fixation was employed for intertrochanteric fractures of the femur. Results A follow-up for average 18 months showed no death. Early complications occurred in three patients including two with pulmonary infection and one with urinary tract infection, who got cured after proper treatment. There was one patient with long-term complication, post-traumatic arthritis. All 23 patients got bone healing, with excellenee rate of 96% according to Harris criteria. There were no complications like breakage of nails, nonunion, eoxa yarn deformity, shortening or external rotation of the lower limb. Conclusions DCS has advantages of simple operation, reliable fixation and coincidence with biomechanical characteristics and hence is one of ideal methods for treatment of intertrochanteric frac-ture of the femur, especially for subtrochanteric fracture, contrary chanteric fractur, fracture involving large pyriform troehanteric and comminuted fractures of sub-trochanteric lateral os integumentale.
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Objective To investigate the relationship between estrogen levels and tenosynovitis in postm-enopausal women. Methods 74 cases of postmenopausal women,including 32 cases of tenesynovitis (group A),42 cases healthy postrnenopausal women for the control group (group B) were observed. 42 cases of normal menstruation women were taken as control group (group C). Results The estrogen level was (89.7066±126.7458) pmol/L in group A,(45.6768±30.6342) pmol/L in group B,and (626.7384±361.5348)pmol/L in group C,There is statistical difference between group A and group C (P<0.05). Conclusions Tenosynovitis incidence in postmeno-pausal women has no significant relationship with the level of estrogen change.
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The content and thought on gradually exploratory experiment teaching of pharmacology was introduced to research the cultivation of innovative talents and good experiment concept.
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This article is to introduce our experience in the application of random controll blind trial technique in experimental teaching of pharmacology.
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The paper reviewed the main methods for the determination of paralytic and diarrhoetic shellfish toxins,including mouse bioassay,immunoassay and high performance liquid chromatography coupled with multiple techniques and so on,and summarized the principles,advantages and disadvantages of these methods.Some newly developed techniques and the development tendency for the detection of paralytic and diarrhetic shellfish poisoning toxins were also described in this paper,in order to give some reference for the detection of marine food in our country.
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0.05).The results differentiated by Sysmex XS-800i showed excellent correlation with those by handwork.Conclusion The performance of the Sysmex XS-800i automated hematology analyzer is satisfied.