BACKGROUND:Tracheal injury suture and the development of a new tracheal prosthesis all need to understand the tensile mechanical properties of tracheal cartilage.so as to repair and rebuild tracheal function.Previous researches on the biomechanics of artificial trachea are many reported.while the biomechanics of human tracheal cartilage is reported less.OBJECTIVE:To investigate the mechanical properties of tracheal cartilage using one-dimensional tensile test method.METHODS:Two fresh cadaver specimens of normal human trachea.with the informed consents of their families.were involved.The specimens were thaw at room temperature,and then tracheal cartilage specimens were cut using scalpel into 20 samples at the length of 25 mm,width 5 mm,thickness 1.8-2.2 mm.The 20 tracheal cartilage samples were subjected to one-dimensional tensile test with Shimadzu electronic universal testing machine Japan,at the tensile test speed of 5 mm/min.The tensile maximum load,maximum displacement,maximum stress,maximum strain,elastic modulus and stress-strain curve of the specimens were observed.RESULTS AND CONCLUSION:The maximum load of human cadaver tracheal cartilage was(60 946±10.377)N,maximumdisplacementwas(1.973±0.159)mm,maximum stresswas(6.229±1.125)Mpa,maximum strainwas(32.825±2.776)%.Tracheal cartilage stress-strain curves was changed along with the index,the initial low slope of the curye was due to the direction of imposed tension was similar with the arrangement of collagen structure,the steep slope represented the tensile strength of collagen.To describe the tracheal cartilage stress-strain relationship in a one-dimensional tension,15 stress-strain data of the tracheal cartilage experimental data adopted polynomial by the least square fitting method,to obtain stress(δ)-strain(ε)relationship forrnula:σ(ε)=-0.111 3e~5+1.602 1e~4-7.821 6e~3+17.995 1e~2+3.624e.It is indicated that tracheal cartilage has a strong capacity to bear Joad and resist deformation,reflecting their viscoelastic mechanical properties of both flexibility and viscosity,supporting that the mechanical properties of cartilage is positively related to cartilage collagen content.

BACKGROUND:Shear mechanical properties of lumbar trabecular bone should be understood in treating osteoporosis,bone remodeling,bone reconstruction,as well as the choice of fracture fixed equipment.OBJECTIVE:To explore whether the shear mechanical properties of lumbar trabecular bone is different in young and aged normal fresh cadavers.METHODS:Experimental samples were from 4 normal fresh corpse,aged 22,28,70 and 75 years,were provided by Department of Anatomy,Norman Bethune Medical University.Spinal column thoracic vertebra L_2-L_5 specimen were obtained from corpse within 1 hour and cut into 40 min×5 mm×5 mm pieces.The specimen were tested on electronic universal testing machine with speed of 5 mm/min,the shear load,stress,strain and other data would be printed automatically,and the morphology of fracture surface was observed.RESULTS AND CONCLUSION:Majority of the fracture surfaces were comminuted,minority were transverse or oblique fracture.The macroscopic observation showed that trabecular arranged compact in the thoracic vertebra cancellous bone of the youth group,which was sparse arrangement and presented with senile osteoporosis in the aged group.The shear force,shear stress and strain of the youth group was greater than that of the aged group[(37.19±3.25),(28.34±3.42) N;(1.49+0.13),(1.13±0.14) MPa;(1.40±0.50)%,(0.90±0.20)%,P＜0.05].It demonstrated that the impact mechanics properties of thoracic vertebra cancellous bone are different between the youth and aged groups.

BACKGROUND:The brachial plexus injury anastomosis suture technique is necessary to understand the mechanics characteristic of brachial plexus nerve stress relaxation.Previous studies mainly focused on single tension mechanics of brechial plexus nerve,but few studies concerning stress relaxation and creeping elasticity.OBJECTIVE:To observe and analyze experimental animal brachial plexus nerve stress relaxation mechanics characteristic in the description manner of function,to provide experimental parameters for clinic.DESIGN,TIME AND SETTING:The experimental observations to use function as a way to describe from 1~(st) to 10~(th_ March,2007 at the Experimental Center of Jilin University.MATERIALS:The experimental male Sprague Dawley rats aged 6 months were provided by Changchun Gaoxin Medicine Animal Experimentation Center.METHODS:The stress relaxation experiment was performed in Experimental animal Brachial plexus Nerve on the the electronic universal testing machine (Shimadzu,Japan).The stress relaxation experiment strain increased speed was 1%/s,setting time of 7 200 seconds.100 empirical data were collected and disposed by one-way linear regression analysis.MAIN OUTCOME MEASURES:The stress relaxation data and curve,the Stress and time change rule were measured.RESULTS:The stress relaxation quantity of animal brachial plexus nerve test specimen at 7 200 s was 0.316 MPa.Stress relaxation curve changed with logarithm.Stress relaxation changed rapidly at 600 seconds,decreased gradually,and reached a balance level at 7 200 seconds.CONCLUSION:The stress relaxation curve changed with the logarithm relations.Brachial plexus has visco-elastic mechanical properties.

Objective To explore the application value of virtual touch tissue quantification(VTQ) technique in differentiating small solid thyroid nodules.Methods The patients with suspiciously malignant thyroid nodules(solitary,size range 5-15 mm),homogeneous and normal color Doppler flow imaging in the rest of thyroid parenchyma,were enrolled in this study.Five repeated measurements were performed on both nodules and extra-nodular tissues using VTQ.A receiver-operating characteristic (ROC) curve was drew according to shear wave velocity(Vs).Results 62 patients with a total of 67 lesions were included in this study,turned out to be 39 malignant and 28 benign.The Vs of malignant group nodules,malignant group extra-nodular tissues,benign group nodules and benign group extra-nodular tissues were (3.91 ±1.85) m/s,(2.03 ± 0.42)m/s,(2.29 ± 0.56)m/s,(1.84 ± 0.45)m/s,respectively.The Vs difference between malignant and benign nodules was statistically significant (P =0.000),while the Vs difference between malignant and benign extra-nodular tissues had no statistical significance (P =0.07).The best cutoff Vs value for distinguishing malignant from benign nodules was 2.78 m/s,with the sensitivity,specificity and accuracy of 76.9％,78.6％ and 80.6％ respectively.The area under ROC curve was 0.84.Conclusions VTQ could evaluate the elasticity of thyroid nodules,and was helpful in the diagnostic work-up of thyroid nodules.

Lipases are important biocatalysts that are widely used in food processing and bio-diesel production. However, organic solvents could inactivate some lipases during applications. Therefore, the efficient cloning and expression of the organic solvent-tolerant lipase is important to its application. In this work, we first found out an organic solvent-tolerant lipase from Staphylococcus saprophyticus M36 and amplified the 741 bp Lipase gene lip3 (GenBank Accession No. FJ979867), by PCR, which encoded a 31.6 kD polypeptide of 247 amino acid residues. But the lipase shared 83% identity with tentative lip3 gene of Staphylococcus saprophyticus (GenBank Accession No. AP008934). We connected the gene with expression vector pET-DsbA, transformed it into Escherichia coli BL21 (DE3), and obtained the recombinant pET-DsbA-lip3. With the induction by 0.4 mmol/L of isopropyl beta-D-thiogalactopyranoside at pH 8.0, OD600 1.0, 25 degrees C for 12 h, the lipase activity reached up to 25.8 U/mL. The lipase expressed was stable in the presence of methanol, n-hexane, and isooctane, n-heptane.
Amino Acid Sequence ; Base Sequence ; Cloning, Molecular ; Enzyme Stability ; Escherichia coli ; genetics ; metabolism ; Lipase ; biosynthesis ; genetics ; Molecular Sequence Data ; Organic Chemicals ; chemistry ; Recombinant Proteins ; biosynthesis ; genetics ; Solvents ; chemistry ; Staphylococcus saprophyticus ; enzymology

Objective:At present,the doctor-patient relationship is tense.The prevalence of negative emotions,such as depression and anxiety,among healthcare workers is increasing every year.Negative attitudes of medical workers toward mental problems may aggravate the doctor-patient conflict and psychological problems of medical workers.This study aims to explore the complex network relationships between outpatient medical workers'attitudes toward mental problems,doctor-patient relationships,and their depression/anxiety levels. Methods:A total of 578 outpatient medical staff from the Second Xiangya Hospital of Central South University(167 males,411 females)completed questionnaires on their attitudes toward mental problems,doctor-patient relationships,and depression/anxiety symptoms.Network analysis was conducted separately to construct the"attitude towards mental problems-doctor-patient relationship network"and"depression-anxiety related network". Results:The edge between"M15(insulting words)"and"D8(waste time)"showed the strongest strength in the"attitude towards mental problems-doctor-patient relationship network",and"M15(insulting words)"had the highest bridge strength in the network.For the analysis of emotional variables,"P1(anhedonia)"showed the most obvious association with"D10(communication difficulties)"in the doctor-patient relationship and"M2(poor quality of life)"in the psychiatric attitudes,and"P1(anhedonia)"was the key bridge symptom in the network. Conclusion:The"insulting words"may be an intervention target for medical workers'attitudes toward mental problems.The"anhedonia"in depression is the potential symptom that needs to be treated.Intervention targeting these variables may be beneficial to improve the mental health level of medical workers and the doctor-patient relationship.