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2020 Vol. 39, No. 1 Published: 2020-02-20

Reviews Communications Regular Papers

Regular Papers

	1	Analysis of Default Mode Network Community Structure in Patients with Alzheimer′s Disease
		Cui Xiaohong, Xiao Jihai, Xiang Jie, Chen Junjie
		DOI: 10.3969/j.issn.0258-8021.2020.01.01
		Studies have shown that dysfunctions of the default mode network (DMN) are associated with Alzheimer′s disease. In this work, in order to further find out the abnormal connective structure of default mode network in patients with Alzheimer′s disease, an unbiased brain network was constructed by using the minimum spanning tree method and tree hierarchical clustering method was used to analyze community structure of DMN in patients with early mild cognitive impairment (EMCI), lately mild cognitive impairment (LMCI), Alzheimer′s disease (AD) and normal controls (NC). In addition, the difference between gyrus rectus and superior frontal gyrus of orbital part, and precuneus and posterior cingulate gyrus was analyzed. At the same time, the centrality of superior temporal gyrus was analyzed. The results showed that DMN was divided into 5 clusters in NC and EMCI, and it was divided into 7 clusters in the LMCI, but it was divided into 9 clusters in AD. There was significant difference between LMCI and AD in the connection between gyrus rectus and superior frontal gyrus of orbital part (P=0.048), LMCI and EMCI in the connection between precuneus and posterior cingulate gyrus (P=0.042). There was a significant difference between LMCI and NC in the connection between precuneus and posterior cingulate gyrus (P=0.016). There was a significant difference in betweenness of superior temporal gyrus between AD and LMCI (P=0.028), LMCI and NC (P=0.001), EMCI and NC (P=0.048). The results showed that with the progress of the disease, the structure of DMN was gradually dispersed, the connection between the brain regions and the centrality were changed. These brain regions mainly include hippocampus, parahippocampal gyrus, precuneus, posterior cingulate gyrus, superior frontal gyrus of orbital part, middle frontal gyrus of orbital part, gyrus rectus and superior temporal gyrus.
		2020 Vol. 39 (1): 1-7 [Abstract] ( 658 ) HTML (1 KB) PDF (1144 KB) ( 485 )

	8	Method for Detecting Pulmonary Nodules Based on Three-Dimensional Dense Network
		Wang Shangli, Jin Gehui, Xu Liang, Jin Wei, Yin Caoqian, Fu Randi
		DOI: 10.3969/j.issn.0258-8021.2020.01.02
		To solve the problem that the detection rate of pulmonary nodules is low and require large amounts of calculation by traditional method which based on three-dimensional features, a more efficient three-dimensional-dense-network based method for pulmonary nodules’ detection was proposed. The method firstly involved the introduction of a densely connected unit into the 3D U-Net to construct a 3D Dense U-Net (3D Densely connected U-Net) network for lung nodule detection. Since 3D Dense U-Net replaced the original ordinary convolution layer of 3D with a densely connected block, it facilitated the maximization of the information flows between layers; it not only solved the problem of feature redundancy in traditional stacked networks, but also speeded up the network training. Additionally, the new method retained the fundamental linking method of U-Net to reuse the underlying features, which enabled an effective obtainment of the candidate nodules. On this basis, in order to solve the problem of false nodules in the candidate nodules, in order to more effectively acquire the features of the nodules and improve the ability of the network to identify the nodules, a three-dimensional dense classification network (3D DenseNet) was used to eliminate false-positive nodules. By testing the data collection of Tianchi Medical AI Competition, the total detection sensitivity for lung nodules using the proposed method reached 94.3%; and the sensitivity of nodules less than 10 mm was 91.5%, and the false-positive rate was 5.9%. The experimental results revealed that the proposed method reached greater sensitivity in detecting small nodules, which not only raised the nodules’ detection rate, but also improved the computational efficiency.
		2020 Vol. 39 (1): 8-18 [Abstract] ( 497 ) HTML (1 KB) PDF (3719 KB) ( 339 )

	19	Prediction and Evaluation of Schizophrenia Symptom by fMRI Brain Connectivity Centrality
		Duan Mingjun, Li Ning, Chang Xin, Li Cheng, Zhang Nan, Ren Youwei, Yang Huanghao, He Hui, Luo Cheng, Yao Dezhong
		DOI: 10.3969/j.issn.0258-8021.2020.01.03
		Schizophrenia is a kind of serious mental disorder. Most of patients with schizophrenia need lifetime treatment of antipsychotic drugs. It is very important to evaluate the effects of drugs for the choice of therapeutic approaches. In this study, the degree centrality (DC) of brain functional connectivity was used to investigate the effects of taking two clinical different kinds of antipsychotic drugs: risperidone and clozapine, aiming to construct a model to predict their effects. The resting-state functional magnetic resonance imaging data were collected from 20 schizophrenia patients therapized with risperidone, 24 patients were treated with clozapine and 30 healthy as controls. The voxel-based DC was evaluated using analysis of variance. The DC in the regions with difference between patients and healthy controls was used in support vector regression (SVR) to construct predictive model for the scores of syndromes in patients with different drugs respectively. Experimental results indicated that the DC was altered in thalamus, insula and primary perception and motor-related cortexes in schizophrenia contrast to healthy controls (P< 0.05). In addition, The SVR model based on the DC in these regions could predict the negative syndrome of patients’ treatment with clozapine (r=0.448, P<0.05), while the syndrome of patients was not predicted in the risperidone group. Therefore, using SVR for the regions with difference in analysis of variance, several main regions related with antipsychotic drugs in schizophrenia were determined, and these findings would contribute to the choice antipsychotic drugs in the future.
		2020 Vol. 39 (1): 19-25 [Abstract] ( 537 ) HTML (1 KB) PDF (4311 KB) ( 417 )

	26	Intelligent Classification and Identification of Composite Colonies Based on Convolutional Neural Network
		Yu Hui, Du Peipei, Liu Xiang, Liu Zheng, Zhu Xianfeng, Cao Yuzhen
		DOI: 10.3969/j.issn.0258-8021.2020.01.04
		To meet the requirement of intelligent morphology classification of compound colonies, a convolution neural network for colony classification was proposed in this work. All connected domains in the culture dish were obtained by level set evolution. Limit corrosion was used to determine the connected domains that seed points were greater than one. Obtaining the convex closures of the connected domains, the concave points were detected. By connecting the corresponding concave points, the connected domains with adhesion were segmented. Herein 600 single colony samples were normalized, and the data were expanded to 30,000 cases by rotating and flipping and superimposing random noise with signal-to-noise ratio not exceeding 5%. Samples of 70% were used as the training set for the network. The network was cross-verified by 10 folds. Samples of 30% were used as the test set. The weighted average accuracy of the four colonies reached 87.50%, of which the classification accuracy of spotted smooth colonies was 86.40%, that of circle like wavy colonies was 87.21%, that of oval colonies was 88.11%, and that of irregular other colonies was 87.25%. Compute unified device architecture (CUDA) was adopted to accelerate the algorithm. The running time was optimized to 1/10 of the original time. In terms of running speed and convenience, the algorithm far exceeded the traditional methods. The statistical results showed that the proposed method could effectively complete the task of intelligent classification and identification of compound colonies. This method showed good expansibility and self-learning function, which had reference value for intelligent analysis of biochemical samples based on images.
		2020 Vol. 39 (1): 26-32 [Abstract] ( 814 ) HTML (1 KB) PDF (4576 KB) ( 562 )

	33	Fuzzy Entropy Analysis of Mental Fatigue Based on EMD DetrendedFluctuation
		Yang Shuo, Li Runze, Ding Jianqing, Xu Guizhi
		DOI: 10.3969/j.issn.0258-8021.2020.01.005
		Mental fatigue is caused by engaging in repeated single or high-load cognitive activities for long time. Short-term mental fatigue can cause decreased attention and reduced work efficiency, while long-term mental fatigue can cause brain damage. Extraction of mental fatigue characteristics can help detect mental fatigue and prevent the harm. Entropy can reflect changes of dynamic complexity under mental fatigue state and is expected to be an indicator for evaluating mental fatigue. However, entropy's extraction of EEG signal characteristics is affected by the superimposed trends in signals, makeing it impossible to accurately describe the dynamic characteristics of the signal and resulting in inconsistent entropy characteristics obtained at different time periods. In order to solve the problems, the empirical mode decomposition (EMD) detrended fluctuation analysis was combined with fuzzy entropy to evaluate the dynamic complexity of EEG signal. The four-hour English scientific paper translation was used as a mental fatigue-inducing task and the EEG signal were recorded from 14 undergraduate volunteers in resting-state and mental fatigue state. The approximate entropy, fuzzy entropy and detrended fuzzy entropy of EEG signals in the two status and the three time periods were compared and analyzed. Results showed that compared with the traditional approximate entropy and fuzzy entropy, the detrended fuzzy entropy in the mental fatigue state was significantly different than that in the resting-state in the left hemisphere dominance (FC3, P=0.022; P5, P=0.007), and the electrodes with significant differences were basically consistent in the three time periods (The P-values of the FC3 in the three time periods are 0.025, 0.017, and 0.012, respectively, and the P-values of the P5 are 0.011, 0.006, and 0.017). It was shown that the detrended fuzzy entropy could better express the difference of brain complexity in two status, and had good time stability. Therefore, EMD-based detrended fuzzy entropy can be used to evaluate the impact of mental fatigue on brain dynamic complexity more quickly and effectively.
		2020 Vol. 39 (1): 33-39 [Abstract] ( 512 ) HTML (1 KB) PDF (4702 KB) ( 346 )

	40	Regression Analysis of Microbial Substructure Based on Tree-Based LASSO
		Xu Xiaomin, Lin Yong
		DOI: 10.3969/j.issn.0258-8021.2020.01.06
		Human microbial composition and function changes have an important impact on their phenotype or disease. When studying the association of microorganisms with human phenotypes or diseases, not only the individual microbial dynamics, but also the overall impact of the community at the taxonomic level should be considered. In this work, a method of regression analysis of microbial substructure based on tree-based LASSO was proposed to analyze the correlation between microbial community and human phenotype. First, a new penalty function was constructed based on phylogenetic tree structure, and the tree structure is analyzed node by node. Second, 148 samples were tested for complex and sparse substructure regression and coefficient evaluation. The regression results of strains in different substructures were analyzed and compared with the traditional LASSO method. The results showed that this method could highlight the tree structure of microbial communities. The regression coefficients of this method on test nodes were 0.122 and 0.127, which were better than those of the traditional LASSO method (0.106 and 0.118). The advantage of this method in identifying microbial structure was verified. In conclusion, the method could better analyze the association between microbial communities and human phenotypes or diseases.
		2020 Vol. 39 (1): 40-49 [Abstract] ( 474 ) HTML (1 KB) PDF (12443 KB) ( 94 )

	50	Peripheral Nerve Noninvasive Stimulation via Temporally Interfering Electric Fields
		Wu Yongliang, Wang Zimu, Ding Xiaoyu, Cang Chen, Zheng Zheng
		DOI: 10.3969/j.issn.0258-8021.2020.01.07
		Peripheral nerve electrical stimulation can be used for sports rehabilitation and chronic neuralgia treatment, but the current spatially selective non-invasive stimulation remains a problem to be solved. A non-invasive peripheral nerve electrical stimulation method that features a certain level of selectivity was developed based on the temporally interfering (TI) electric field. The rat sciatic nerve was tested and the stimulating electrodes were arranged in the direction parallel to the nerve on the ventral and dorsal skin of the thigh. The TI stimulation peak was localized to the nerve for selective stimulation by the scan of interfering electric field. The results showed that optimal electrical parameters, through which the electrical field was delivered to the nerve, could be acquired by scanning without knowing the exact location of the nerve in advance. Thus, selective non-invasive stimulation of nerves could be achieved and the control of the intensity of stimulation could be realized under the premise of keeping the stimulation focus fixed. On this basis, the stimulation threshold I_T of TI electric field on rat sciatic nerve was explored and I_Tof different conditions were measured as well, including fixing frequency difference Δf=0.5 Hz (n=12), changing the frequency f=1～6 kHz and fixed f=5 kHz (n=11), changing the frequency difference Δf=0.5～10 Hz, at the same time, compared with that of equal amplitude kHz electric field (n=7). The results demonstrated that the I_T of the equal-amplitude kHz electric field is significantly higher than that of the TI electric field (P<0.05), and there is a significant difference in the I_T at different frequencies f(P<0.05), while no remarkable difference in the I_T of different Δf(P<0.05), which was different between two frequencies, was observed, indicating that the stimulation threshold of TI electric field on rat sciatic nerve was affected by frather than Δf, and the stimulation threshold I_T was proportional to the frequency f.
		2020 Vol. 39 (1): 50-56 [Abstract] ( 501 ) HTML (1 KB) PDF (1665 KB) ( 697 )

	57	Hardware Implementation and Discharge Performance Comparison of Nerve Synapses Based on FPGA
		Chen Kai, Lu Mai, Yi Feihong, Wang Chao
		DOI: 10.3969/j.issn.0258-8021.2020.01.08
		At present, there are few studies on the hardware implementation of chemical synaptic, the use of FPGA chip to realize chemical synapses is of great value to the realization of neural network hardware. In this work, based on the DSP Builder model, the DSP Builder model of the chemical synapse was reasonably splited, and then each module was compiled and run in the software environment corresponding to the FPGA, and finally downloaded to the FPGA core chip, using the FPGA hardware to realize five kinds of chemical synapses based on different mechanisms. The correlation coefficient method was used to compare the pre-synaptic neuron action potential, post-synaptic neuron action potential and synaptic current amplitude between the simulation results and the hardware results in the same cycle. Five chemical synapses realized by hardware could better transmit action potentials, but each model consumed different resources. The internal multiplier resources consumed by Model 3 (69%) were about 2 times that of Model 5 (31%), indicating that the higher the mathematical complexity of the synapse model, the more multiplier resources it consumed. The comparison of the correlation coefficient method showed that the correlation of model 3 was the highest, which was 0.791 3, and the correlation coefficient of model 4 was the lowest, which was 0.693 5. Although Model 3 had the high mathematical complexity and hardware resource consumption, its performance was the best. The five synaptic models implemented by hardware could better represent the one-way transmission of chemical synapses. The model 5 had low hardware resource consumption and high correlation. The model 5 was recommended as the first choice for hardware realization of chemical synapses.
		2020 Vol. 39 (1): 57-66 [Abstract] ( 493 ) HTML (1 KB) PDF (2837 KB) ( 349 )

	67	Experimental Study on a New Type of Chinese-Made Mitral Valve Clip System
		Li Bin, Luo Xiaokang, Zhang Dong, Luo Fuliang, Li Bo, Pan Wenzhi, Tang Yue
		DOI: 10.3969/j.issn.0258-8021.2020.01.09
		We conducted an animal experiment to evaluate the feasibility and safety of a new type of Chinese-made mitral valve clip system. Fourteen pigs were divided into experimental group (n=10) and the control group (n=4). The experimental group was implanted with a new type of mitral valve clip, and the control group underwent traditional mitral valve repair. Echocardiography and blood testing were performed before and after operation. Tissue samples were taken from animals after euthanasia 140 days postoperatively. Pathological examination of heart and major organs were conducted. Results: In total, 8 animals in the experimental group and 4 animals in the control group reached the end of the experiment. No serious complications such as clip falling off, heart rupture, valve injury, intractable arrhythmia, viscera embolization, heart failure and death occurred in all animals. Echocardiography showed that all the clips were fixed at the mitral valve, and no statistically significant difference in mitral pressure gradient was found between the two groups. The implantation device had no significant influence on the hepatic and renal function. Pathological examination revealed chronic inflammation, mucinous degeneration and a small amount of bleeding in the leaflets around the clip. No damages to the mitral valve and heart tissue were observed. No thromboembolism was detected in the major organs. Conclusions: Animal experiments suggested that the new type of Chinese-made mitral valve clip system had good biocompatibility and could be effectively fixed at the mitral valve without causing serious complications.
		2020 Vol. 39 (1): 67-73 [Abstract] ( 485 ) HTML (1 KB) PDF (4240 KB) ( 479 )

	74	Effect of Segmental Curvature on Stress Evolution of Lumbar Intervertebral Disc under Axial Vibration
		Xie Yixiang, Zhang Han, Zhu Weiping
		DOI: 10.3969/j.issn.0258-8021.2020.01.10
		To study the effect of segmental curvature on the stress evolution of lumbar intervertebral disc when the lumbar motion segment is subjected to long-term axial vibration. Based on the CT scan data of human lumbar spine L4～5 segment, the finite element model of human lumbar spine L4～5 segment was constructed. Poroelastic property was assigned to the intervertebral disc and the finite element model was validated. Based on this finite element model, processes of L4～5 segment subjected to a 1000-s axial vibration with different segmental curvatures (neutral posture, 2° of extension, 2° of flexion) were simulated, and the stress evolution of the intervertebral disc in those cases were obtained. With each segmental curvature, the peak axial stress of the annulus fibrosus of the intervertebral disc existed in its posterolateral part. With each segmental curvature, the peak axial stress of the annulus fibrosus increased nonlinearly and the growth rate was decreased. In all cases, the peak axial stress of the annulus fibrosus was inclined to an equilibrium state at 1000 s. At 1000 s, the peak axial stress of the annulus fibrosus in the case with the L4～5 segment in 2° of extension was 39% greater than that in the case with the L4～5 segment in neutral posture and 109% greater than that in the case with the L4～5 segment in 2° of flexion. With each curvature, the axial stress of the nucleus pulposus also increased nonlinearly and the growth rate was decreased. At 1000s, the axial stress of the nucleus pulposus in the case with the L4～5 segment in 2° of extension was slightly less than those in the other two cases. The intervertebral disc was damaged most severely when the L4～5 segment was loaded in 2° of extension, while it suffered the slightest damage when the L4～5 segment was loaded in 2° of flexion. When exposed to the whole body vibration for a long time, an extended posture of lumbar spine should be avoided, and a slight flexed posture of lumbar spine can protect the intervertebral disc.
		2020 Vol. 39 (1): 74-83 [Abstract] ( 452 ) HTML (1 KB) PDF (3575 KB) ( 297 )

	84	The Optimized Analysis on the Distribution Gradient of Material Attributes of Femur Finite Element Model
		Jin Qiankun, Wang Wei, He Shengwei, He Feixiong, Chen Bingzhi, Fu Yanmian
		DOI: 10.3969/j.issn.0258-8021.2020.01.11
		The aim of this work is to investigate the optimized analysis on the femur finite element model in the distribution gradient of material attributes, getting the precise and economic divided layers, which can be used as the theoretical support for the application of CT gray value assignment in the research area of medical finite element. The femur of an adult volunteer was firstly selected for CT scanning, the obtained DICOM format CT serial medicinal image data were input into Mimics, and the 3D rendering model was constructed. On this basis, using SolidWorks to substantiate the model, importing it into HyperMesh for volume mesh division, and then returning to Mimics, choosing layer 2, 4, 5, 10, 50, 100, 200 and 400 eight kinds of the gradient for material assignment. Finally, the working condition of the finite element model was set in ABAQUS software for simulation analysis. At the same time, the femur proxima finite element was established, and its validity was verified through the comparative analysis with literature data. Results showed that the level of stress and strain of the established femur finite element model had similar results with the experimental results in the literature; thus the effectiveness of the femoral finite element model was fully verified. The optimized analysis on the distribution gradient of material attributes: compared with the material properties of other layers, the stress of layer 2, 4, 5 and 400 was significantly different (P<0.05), and the stress between the four groups of material properties was significantly different (P<0.05),while the stress results of layer 10, 50, 100 and 200 were not significantly different. The material properties of the finite element model should be divided in an appropriate way. We found out that the material properties in 10 layers could not only improve the calculation speed and save the calculation amount, but also ensure the accuracy of the calculation results; the CT gray value assignment could be used to the analysis on the clinical individualized rapid finite element simulation.
		2020 Vol. 39 (1): 84-90 [Abstract] ( 454 ) HTML (1 KB) PDF (10701 KB) ( 65 )

	91	Research on the Relationship Between Mechanical Properties of 3D Printed Hydroxyapatite Scaffolds and Inner Structures
		Li Xiangcheng, Suo Hairui, Wang Ling, Xu Mingen
		DOI: 10.3969/j.issn.0258-8021.2020.01.12
		3D printed bone tissue engineering scaffolds are becoming hotspot recently, and preparation of bone tissue engineering scaffolds with high porosity and sufficient mechanical properties is still one of the difficulties in current research. The purpose of this study was to investigate the effects of different filling angle structures on the mechanical properties of 3D printing scaffold with the same porosity. Firstly, three different filling angle (45°, 60°, 90°) scaffold structures with the same porosity were designed by SolidWorks software, the structure of the intersection point was used as the minimum support unit of the scaffold, and it′s mechanical properties were simulated by ABAQUS software. Next, the compression modulus of the structure unit was accumulated to investigate the effect of filling angle on the mechanical properties of the scaffold. Three kinds of hydroxyapatite scaffolds with inner structure were prepared by 3D printing, and the porosity and mechanical properties of the scaffolds were tested to verify the simulation results. Results showed that the compression modulus ratio of the three inner structures obtained by simulation was E_s(90°)∶E_s(60°)∶E_s (45°)=12.3:10.9:10.0. There were no significant differences in the porosity of the hydroxyapatite scaffolds among the three different filling angles (90°, 60°, 45°), and the compression modulus ratio was E_s(90°):E_s(60°):E_s(45°)=15.4:13.1:10.0, consistent with the simulation results. The 90° scaffold had the highest compressive strength (7.36 ± 0.63) MPa and compressive modulus (33.55 ± 2.49) MPa. Compared with the 45° scaffold, the compressive strength of 90° scaffold was increased by 74.8% and the compressive modulus was increased by 55.18%. With the same porosity, the scaffold with smaller area of single pore showed higher compressive modulus and compressive strength. This study provided an analytical method and theoretical basis for the preparation of 3D printed biological scaffolds with optimal inner structure.
		2020 Vol. 39 (1): 91-96 [Abstract] ( 582 ) HTML (1 KB) PDF (4812 KB) ( 298 )

Reviews

	97	Fabrication of Organ-on-a-Chip by 3D Printing Technology
		Liu Yan, Yang Qingzhen, Chen Xiaoming, Gu Fangwei, Zhang Hui
		DOI: 10.3969/j.issn.0258-8021.2020.01.13
		Organ-on-a-chip is an emerging in vitro biological model with great prospects in biomedical researches. However, its development is often limited by the cumbersome and expensive fabrication process. Recently, researchers have adopted 3D printing technology into the fabrication and therefore made this process simpler and less expensive. Besides, this strategy also increased the complexity of chip structure and allowed the one-step fabrication. 3D printing technology has strongly promoted organ-on-a-chip related researches and contributed to its wide application. This paper reviewed the research status of 3D printing technology in the fabrication of organ-on-a-chip, including the development background of organ-on-a-chip, limitations of traditional fabrication methods, the technical classification and biomedical applications of 3D printing technology.Five 3D printing methods were listed based on different forming principles, and their characteristics and applications in chip fabrication were compared as well. Besides, the applications of 3D printing technology in the construction of liver, kidney, blood vessel, heart and other organs-on-chips were also discussed. Finally, we concluded with our thoughts on the challenges and future perspectives of this technology.
		2020 Vol. 39 (1): 97-108 [Abstract] ( 840 ) HTML (1 KB) PDF (4728 KB) ( 868 )

	109	Exosomes and Their Applications in Tissue Engineering
		Liu Yufei, Zhang Zhiling, Wang Yanying, Dong Yunsheng, Zhang Lin, Wang Shufang
		DOI: 10.3969/j.issn.0258-8021.2020.01.14
		Mesenchymal stem cells are adult stem cells with self-renewal ability, which are widely found in tissues such as bone marrow, adipose tissue, and peripheral blood. Mesenchymal stem cells have many therapeutic effects in the clinic currently, which brings hope for the cure of many diseases. Recent studies have shown that mesenchymal stem cells release many kinds of small molecular substances, among them, exosomes carrying large amounts of biologically active factors can mediate communication between cells and play a role in physiological and pathological processes. As a research hotspot of cell-free tissue engineering in recent years, exosomes have contributed to solutions in clinical applications of regenerative medicine to some extent, such as seed cell source, quantity and immune rejection, and at the same time in disease diagnosis and treatment. This paper introduces the methods of exosome extraction and identification and its potential application in tissue engineering and discusses its future development.
		2020 Vol. 39 (1): 109-113 [Abstract] ( 654 ) HTML (1 KB) PDF (792 KB) ( 611 )

	114	Progress of Carriers and Techniques for Therapeutic Enzymes
		Wan Shengli, Yang Gang, Ye Yun
		DOI: 10.3969/j.issn.0258-8021.2020.01.15
		Therapeutic enzymes are a class of medicines with medical effects. In recent years, more and more attention has been paid to the development of new carriers and new technologies for therapeutic enzymes. In this review, new carriers of therapeutic enzymes, including liposomes, nanoparticles, micelles, red blood cells, inclusion complexes and microemulsions, were summarized. And new technologies of therapeutic enzymes, such as supercritical fluid technology and chemical modification technology, were explained. Application examples showed that both new carriers and new technologies can optimize therapeutic enzymes. New carriers and technologies have broad prospects in the research and development of therapeutic enzymes.
		2020 Vol. 39 (1): 114-118 [Abstract] ( 395 ) HTML (1 KB) PDF (763 KB) ( 262 )

Communications

	119	Fracture Toughness and Fractography of Pyrolytic Carbon for Artificial Heart Valve
		Zhang Jianhui, Ruan Yepeng, Sun Zhenguo
		DOI: 10.3969/j.issn.0258-8021.2020.01.16

		2020 Vol. 39 (1): 119-123 [Abstract] ( 448 ) HTML (1 KB) PDF (3832 KB) ( 232 )

	124	Cytotoxicity Study of Cobalt Alloys and Titanium Alloys
		She Zhizhong, Yu Shu, Li Yun-ping, Yin Yanxiong, Zhong Hui, Li Xiao, Xiao Tao, Yang Hu
		DOI: 10.3969/j.issn.0258-8021.2020.01.17

		2020 Vol. 39 (1): 124-128 [Abstract] ( 400 ) HTML (1 KB) PDF (6943 KB) ( 464 )

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