ObjectiveTo manufacture a polycaprolactone (PCL)/type Ⅰ collagen (COL Ⅰ) tissue engineered meniscus scaffold (hereinafter referred to as PCL/COL Ⅰ meniscus scaffold) by three-dimensional (3D) printing with low temperature deposition technique and to study its physicochemical properties.MethodsFirst, the 15% PCL/4% COLⅠ composite solution and 15% PCL simple solution were prepared. Then, 15% PCL/4% COL Ⅰmeniscus scaffold and 15% PCL meniscal scaffold were prepared by using 3D printing with low temperature deposition techniques. The morphology and microstructure of the scaffolds were observed by gross observation and scanning electron microscope. The compression modulus and tensile modulus of the scaffolds were measured by biomechanical test. The components of the scaffolds were analyzed by Fourier transform infrared spectroscopy (FTIR). The contact angle of the scaffold surface was measured. The meniscus cells of rabbits were cultured with the two scaffold extracts and scaffolds, respectively. After cultured, the cell proliferations were detected by cell counting kit 8 (CCK-8), and the normal cultured cells were used as controls. Cell adhesion and growth of scaffold-cell complex were observed by scanning electron microscope.ResultsAccording to the gross and scanning electron microscope observations, two scaffolds had orientated 3D microstructures and pores, but the surface of the PCL/COLⅠ meniscus scaffold was rougher than the PCL meniscus scaffold. Biomechanical analysis showed that the tensile modulus and compression modulus of the PCL/COL Ⅰ meniscus scaffold were not significantly different from those of the PCL meniscus scaffold (P>0.05). FTIR analysis results showed that COL Ⅰ and PCL were successful mixed in PCL/ COL Ⅰ meniscus scaffolds. The contact angle of PCL/COLⅠ meniscus scaffold [(83.19±7.49)°] was significantly lower than that of PCL meniscus scaffold [(111.13±5.70)°] (t=6.638, P=0.000). The results of the CCK-8 assay indicated that with time, the number of cells cultured in two scaffold extracts showed an increasing trend, and there was no significant difference when compared with the control group (P>0.05). Scanning electron microscope observation showed that the cells attached on the PCL/ COL Ⅰ meniscus scaffold more than that on the PCL scaffold.ConclusionPCL/COLⅠmeniscus scaffolds are prepared by 3D printing with low temperature deposition technique, which has excellent physicochemical properties without cytotoxicity. PCL/COLⅠmeniscus scaffold is expected to be used as the material for meniscus tissue engineering.
The nondestructive reconstruction of three-dimensional (3D) temperature field in biological tissue is always an important problem to be resolved in biomedical engineering field. This paper presents a novel method of nondestructive reconstruction of 3D temperature field in biological tissue based on multi-island genetic algorithm (MIGA). By this method, the resolving of inverse problem of bio-heat transfer is transformed to be a solving process of direct problem. An experiment and its corresponding simulation were carried out to verify the feasibility and reliability. In the experiment a high purity polypropylene material, whose thermophysical parameters were similar to the fat tissue being tested, were adopted so that it could avoid the negative results created by the other factors. We set the position P(x, y, z) as the point heat source in the biological tissue and its temperature t as optimization variable, got the experimental temperature values of the points in a module surface, subtracted them from the corresponding simulating temperature values in the same module surface, and then took the sum of absolute value. We took it as the objective function of successive iteration. It was found that the less the target value was, the more optimal the current variables, i.e. the heat source position and the temperature values, were. To improve the optimization efficiency, a novel establishment method of objective function was also provided. The simulating position and experimental position of heat source were very approximate to each other. When the optimum values are determined, the corresponding 3D temperature field is also confirmed, and the temperature distribution of arbitrary section can be acquired. The MIGA can be well applied in the reconstruction of 3D temperature field in biological tissue. Because of the differences between the MIGA and the traditional numerical methods, we do not have to acquire all the data of surface. It is convenient and fast, and shows a prosperous application future.
Objective To evaluate which is better method zymogen or low temperature frozen in removing vascular endothelial cell so as to lay a foundation for creating a kind of brace which is not to be rejected and the same as own blood vessel. Methods Fresh and not damaged umbilical blood vessel was collected from natural labour women, human umbilical blood vessel was remove carefully from normal foetus, then was put into disinfectant at 37℃ for 24 hours. They were divided into 3 groups:normal group(NG),zymogen group(ZG) and low temperature frozen group(LG). ZG: 0.1% collagenⅡ enzyme was addedin umbilical blood vessel and closed the both sides and the vascular endothelialcell was removed in 37℃ water. LG:Umbilical blood vessel was put into liquidnitrogen for 24 hours after frozened step by step, and then it was put into 37℃ water for 30-60 s and the vascular endothelial cells were washed away by normal saline. NG:Umbilical blood vessel was kept into 4℃ Kerb’s liquid. The bacteria were culturedin each group. The samples were stained by HE,elastic fiber and collagen fiberwere observed by light and scanning electron microscope. The difference of compliance was compared. Human leukocyte antigen ABC(HLA-ABC) and HLA-DR were observed by immunohistochemical method and the expression of antigen of umbilical blood vessel was analysed. Results In LG, umbilical vascular endothelial cells were removed completely; artery showed vertical smooth muscle and vein showed elastic membrane. InZG, umbilical vascular endothelial cells were removed completely after 20 minutes;artery showed vertical smooth muscle cells and vein showed lower endothelial layer. The vascular compliance in LG was higher than that in NG, and the latter was also higher than that in ZG,but showing no significant differences (Pgt;0.05). The compliance of umbilical vein was 2-3 times as much asthat of umbilical artery.The expression of HLA-ABC and HLA-DR in LG andZG were lower than that in NG, showing significant differences (Plt;0.01). Conclusion Low temperature frozen methodand zymogen method(0.1% collagen Ⅱ enzyme for 20 min) can remove vascular endothelial cells of human umbilical blood vessel completely.Low temperature frozenmethod was better than zymogen method.
ObjectiveTo discuss the safety and effectiveness of the improved technique by comparing the effects of low temperature bone cement infusion before and after the improvement in the percutaneous vertebroplasty (PVP).MethodsThe clinical data of 170 patients (184 vertebrae) with osteoporotic vertebral compression fracture who met the selection criteria between January 2016 and January 2018 were retrospectively analyzed. All patients were treated with PVP by low-temperature bone cement perfusion technology. According to the technical improvement or not, the patients were divided into two groups: the group before the technical improvement (group A, 95 cases) and the group after the technical improvement (group B, 75 cases). In group A, the patients were treated by keeping the temperature of bone cement at 0℃ and parallel puncture; in group B, the patients were treated by increasing the temperature of bone cement or reducing the time of bone cement in ice salt water and cross puncture. There was no significant difference in gender, age, disease duration, T value of bone mineral density, operative segment, and preoperative vertebral compression rate, visual analogue scale (VAS) score between the two groups (P>0.05). CT examination was performed immediately after operation, and the leakage rate of bone cement was calculated. The amount of bone cement perfusion and the proportion of bone cement in contact with the upper and lower endplates at the same time were compared between the two groups. The vertebral compression rate was calculated and the VAS score was used to evaluate the pain before operation, at immediate after operation, and last follow-up.ResultsThere was no complication such as incision infection, spinal nerve injury, or pulmonary embolism in both groups. There was no significant difference in the amount of bone cement perfusion between groups A and B (t=0.175, P=0.861). There were 38 vertebral bodies (36.89%) in group A and 49 vertebral bodies (60.49%) in group B exposed to bone cement contacting with the upper and lower endplates at the same time, showing significant difference (χ2=10.132, P=0.001). Bone cement leakage occurred in 19 vertebral bodies (18.45%) in group A and 6 vertebral bodies (7.41%) in group B, also showing significant difference (χ2=4.706, P=0.030). The patients in group A and group B were followed up (13.3±1.2) months and (11.5±1.1) months, respectively. The vertebral compression rates of the two groups at immediate after operation were significantly lower than those before operation (P<0.05), but the vertebral compression rate of group A at last follow-up was significantly higher than that at immediate after operation (P<0.05), and there was no significant difference in group B between at immediate after operation and at last follow-up (P>0.05). The VAS scores of the two groups at immediate after operation were significantly lower than those before operation (P<0.05); but the VAS scores of group A at last follow-up were significantly higher than those at immediate after operation (P<0.05) and there was no siginificant difference in group B (P>0.05). There was no significant difference in VAS scores between the two groups at immediate after operation (t=0.380, P=0.705); but at last follow-up, VAS score in group B was significantly lower than that in group A (t=3.627, P=0.000).ConclusionThe improved advanced low-temperature bone cement perfusion technology during PVP by increasing the viscosity of bone cement combined with cross-puncture technology, can reduce bone cement leakage, improve the distribution of bone cement in the vertebral body, and reduce the risk of vertebral collapse, and achieve better effectiveness.
Objective To conduct a systematic review on the Electrocardiogram (ECG) changes in the workers exposed to high temperatures by means of meta-analysis.Methods The retrospective cohort studies on the relationship between high temperature and ECG abnormalities published from 1990 to May 2009 were searched in CNKI, VIP, WanFang database and CBM database. The literatures meeting the inclusive criteria were selected, the quality was assessed, the data were extracted, and the meta-analyses were conducted with RevMan 4.2.2 software. Results A total of 20 studies were included. The results of meta-analyses showed: the ECG abnormality rate of the high-temperature group was obviously superior to that of the control group with significant difference (OR=2.76, 95%CI 2.37 to 3.20, Plt;0.000 01). The high-temperature severely affected left ventricular hypertrophy (OR=3.49, 95%CI 2.83 to 4.31, Plt;0.000 01), sinus bradycardia (OR=2.83, 95%CI 2.33 to 3.43, Plt;0.000 01), and changes in ST-T segment (OR=2.63, 95%CI 1.48 to 4.68, P=0.000 10), which indicated that the abnormal changes of ECG, such as left ventricular hypertrophy, sinus tachycardia, sinus bradycardia, and changes in ST-T segment could be the sensitive indexes to monitor cardiovascular disease of workers exposed to high-temperature. Conclusion The incidence of ECG abnormalities caused by high-temperature operation is obviously superior to that of the control group, so it is required to strengthen the health monitoring and labor protection for the workers exposed to high temperature.
Numerical simulation is one of the most significant methods to predict the temperature distribution in high-intensity focused ultrasound (HIFU) therapy. In this study, the adopted numerical simulation was used based on a transcranial ultrasound therapy model taking a human skull as a reference. The approximation of the Westervelt formula and the Pennes bio-heat conduction equation were applied to the simulation of the transcranial temperature distribution. According to the temperature distribution and the Time Reversal theory, the position of the treatable focal region was corrected and the hot spot existing in the skull was eliminated. Furthermore, the influence of the exposure time, input power and the distance between transducer and skull on the temperature distribution was analyzed. The results showed that the position of the focal region could be corrected and the hot spot was eliminated using the Time Reversal theory without affecting the focus. The focal region above 60℃ could be formed at the superficial tissue located from the skull of 20 mm using the hot spot elimination method and the volume of the focal region increases with the exposure time and the input power in a nonlinear form. When the same volume of the focal region was obtained, the more power was inputted, the less the exposure time was needed. Moreover, the volume of the focal region was influenced by the distance between the transducer and the skull.
Objective To investigate the construction of a novel tissue engineered meniscus scaffold based on low temperature deposition three-dimenisonal (3D) printing technology and evaluate its biocompatibility. Methods The fresh pig meniscus was decellularized by improved physicochemical method to obtain decellularized meniscus matrix homogenate. Gross observation, HE staining, and DAPI staining were used to observe the decellularization effect. Toluidine blue staining, safranin O staining, and sirius red staining were used to evaluate the retention of mucopolysaccharide and collagen. Then, the decellularized meniscus matrix bioink was prepared, and the new tissue engineered meniscus scaffold was prepared by low temperature deposition 3D printing technology. Scanning electron microscopy was used to observe the microstructure. After co-culture with adipose-derived stem cells, the cell compatibility of the scaffolds was observed by cell counting kit 8 (CCK-8), and the cell activity and morphology were observed by dead/live cell staining and cytoskeleton staining. The inflammatory cell infiltration and degradation of the scaffolds were evaluated by subcutaneous experiment in rats. Results The decellularized meniscus matrix homogenate appeared as a transparent gel. DAPI and histological staining showed that the immunogenic nucleic acids were effectively removed and the active components of mucopolysaccharide and collagen were remained. The new tissue engineered meniscus scaffolds was constructed by low temperature deposition 3D printing technology and it had macroporous-microporous microstructures under scanning electron microscopy. CCK-8 test showed that the scaffolds had good cell compatibility. Dead/live cell staining showed that the scaffold could effectively maintain cell viability (>90%). Cytoskeleton staining showed that the scaffolds were benefit for cell adhesion and spreading. After 1 week of subcutaneous implantation of the scaffolds in rats, there was a mild inflammatory response, but no significant inflammatory response was observed after 3 weeks, and the scaffolds gradually degraded. Conclusion The novel tissue engineered meniscus scaffold constructed by low temperature deposition 3D printing technology has a graded macroporous-microporous microstructure and good cytocompatibility, which is conducive to cell adhesion and growth, laying the foundation for the in vivo research of tissue engineered meniscus scaffolds in the next step.
Objective To explore impact of climate change on aortic dissection and to put forward a new way about prediction and prevention of aortic dissection. Methods We retrospectively analyzed the characteristics of acute aortic dissection patients came from Hebei province in Fuwai Hospital between 2010 and 2016 year. Meanwhile, we collected monthly maximum temperature, minimum temperature, average temperature, average pressure, amount of rainfall, sunshine, humidity and other meteorological data. Generalized model was implied to explore climate change and the incidence of aortic dissection. Results A total of 1 121 acute aortic dissection patients from Hebei province were admitted in Fuwai Hospital during the period of 6 years. There were 774 patients were type A aortic dissection, and 347 patients were type B aortic dissection. The average age was 51.4±12.0 years. There were 873 males and 248 females. There were 889 (79.3%) patients with hypertension, 99 (8.83%) with Marfan syndrome. It was found that temperature, humidity and air pressure were all statistically significant for indication aortic dissection through single variable analysis (P<0.01). The temperature was only variable by one-way analysis of variance (P<0.01). The lowest temperature has the best predictive effect on the occurrence of aortic dissection. The relative risk was 1.02 with 95% confidence interval 1.02 to 1.03. Conclusion The change of climatic conditions can affect the occurrence of aortic dissection, and the lowest temperature is an important trigger factor for aortic dissection onset.
The flushing pump which is applied to clean operative wound has no temperature controlling function up to now, and doctors have to prepare the flushing fluid that has previously been warmed. The flushing pump system with medical constant temperature designed in our laboratory can absorb flushing fluid at the room temperature, and then eject flushing fluid with the temperature in accordance with the requirements of operations at a controlled constant flow rate. The system combines flow rate control with temperature control functions. The flushing pump system includes flushing part, temperature controlling part, key inputting part, liquid crystal displaying part and exceptional situation monitoring part. The present paper introduces the design method and principle of each part of the system at first, and then gives the debug method of all the system parameters. Finally the paper discusses the performance of the system according to the result of the experiment.
Objective To investigate the clinical efficacy and safety of coblation-assisted adenotonsillectomy for treatment of children with obstructive sleep apnea hypopnea syndrome (OSAHS). Methods From June 2007 to May 2008, after monitoring polysomnography (PSG) confirmed 82 cases of OSAHS in children aged 3 to 14 years, with an average age of 6.2 years old, the ENT CoblatorII surgical instrument made by Arthrocare in the US and one-time EVac 70 T amp; A segment was used under complete anesthesia to remove tonsils and(or)adenoid ablation. Polysomnography monitoring was used preoperatively and 6 months postoperatively to determine the therapeutic effect. Results No significant complications occurred among the children both during the operation and postoperatively. Patients were followed for 6 months, and a satisfactory effect was achieved. The lowest oxygen saturation (LSaO2) improved significantly (Plt;0.001); the apnea-hypopnea index (AHI) decreased significantly after the operation (Plt;0.001). In accordance with OSAHS diagnosis and efficacy evaluation standards, 45 patients were cured after 6 months, 21 patients showed an excellent effect, 10 patients showed a good effect, six patients had no effect, and the total effective rate was 92.6%. Conclusion Low-temperature coblation-assisted adenotonsillectomy has good clinical efficacy with a shortened surgical time, less intraoperative and postoperative blood loss, less postoperative pain, few complications, and a simple operation procedure. It can effectively expand the nasopharynx, oropharynx ventilation cross-sectional area, lift the upper airway obstruction, and can be especially suitable for surgical treatment of children with OSAHS.