Publications (64)148.52 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: In this article, a simple self-adaptive neuron based on a position state observer has been proposed to inhibit the influence of load disturbances and accomplish a self-adaptive correction of the moment of inertia. In the process of inertial correction, the error of the position state observer is gradually reduced that facilitates the simultaneous optimisation of the position observer and moment of inertia. Furthermore, it allows accurate prediction of the position value by the position state observer in the subsequent control cycle. Simulations and experiments indicate that the designed controller performs with better adaptive response and robustness compared to the controller that does not implement the proposed method, and that the position state observer estimates the position accurately, a response associated with numerous advantages for practical applications.
- [Show abstract] [Hide abstract] ABSTRACT: The voltage control model and the rotor kinematic model of PMSM(permanent magnet synchronous motor) are analyzed to improve the feedback accuracy of servo control system and to solve the delay problem of feedback signal. The analyzing results are further used to analyze the work timing of control system's feedback loop and the number of hysteretic cycles is obtained. Then, a first level state observer of current and position for PMSM is proposed. The current and position values in the current control cycle are used to obtain accurate estimations of the current and position values in the next control cycle, and the observation output of the first level state observer is served as the input of the second level state observer so that the high frequency oscillation and the time-delay of the current and position's feedback signal can be further suppressed. Results show that the second level state observer of current and position has a significant inhibition on the high frequency noise and an accurate prediction on the feedback value. The observation error of the second level position is less than 0.005 rad, and the high frequency noise included in feedback has is eliminated. When the proposed method is applied in an AC servo control system for position control with high speed and high response, the response frequency of the system reaches 200 Hz, and acceleration arrives at 62 831 rad/s2, and its positioning accuracy is 1.5, while the system's phase current is stable. It can be concluded that the proposed method realizes the accurate observation on current and position values.
- [Show abstract] [Hide abstract] ABSTRACT: In this paper, a method of combining modified space vector control (SVPWM) and sinusoidal pulse width modulation (SPWM) control has been proposed for the three-phase permanent magnet synchronous motor (PMSM). This method solves the problem of the torque ripple when the motor starts running and the hardness to control zero axis component when use SVPWM control method. The proposed method uses SPWM control method when the motor starts running or low speed to ensure the stability of the zero axis component of the control system, and utilize the SVPWM method when the motor at high speed to ensure the stability of the torque ripple of the system. So the method made full use of the advantages of SVPWM and SPWM method respectively. Dynamic response and power quality performance are comparatively analyzed for this method. This method uses PI- IP control structure to further improve the robustness of the control system and the response performance. The simulation and experimental results show the dynamic response of the control structure. In order to guarantee the validity of the data, utilize a high precision identification system to guarantee the precision of the parameter used in control system. This paper gives a detailed description of how to use the method mentioned to realize the PWM output and the control structure used. This method is more efficiently and generates less harmonic distortion when compared with traditional method.
- [Show abstract] [Hide abstract] ABSTRACT: We aimed to analyze the association between the distribution of dendritic cells (DC) with expression of tumor-infiltrating T lymphocytes and clinicopathologic parameters with prognosis in epithelial ovarian cancer (EOC). Thirty-three EOC patient samples were surgically resected, and pathology was examined for clinicopathological variables. Expression of S-100, CD1a, CD45RA and CD45RO was detected using the avidin-biotin complex immunohistochemical technique. The correlation of protein expression with surgical and pathological stage, histological grade, pathological type and prognosis was analyzed. There was significant difference in the CD45RA positive rate in early- and advanced-stage EOC with 50 and 10.5%, respectively (P<0.05). Univariate analysis showed that CD45RO, histological grade and surgical-pathological staging were all factors that influenced the prognosis of patients with EOC. Higher survival rates were found in patients with harboring populations of CD1a(+) DC and CD45RO(+) T lymphocytes or populations of S-100(+) DC and CD45RO(+) T lymphocytes (P<0.05). In addition, histological grade is related to cumulative survival rate. The higher degree of cell differentiation presented better outcome. In conclusion, EOC patients with populations of DC and CD45RO(+) T lymphocytes had a higher survival rate. Histological grade and surgical-pathological stage were independent factors affecting prognosis.Cancer Gene Therapy advance online publication, 27 February 2015; doi:10.1038/cgt.2015.7.
- [Show abstract] [Hide abstract] ABSTRACT: This article presents a double interrupt and frequency-doubled angle compensation control method based on the minimum inductance characteristic of high-speed motor. Moreover, this article designs a proportional-integral-integral-proportional (PI-IP) control structure to realise that the control system can track the d-axis current step response within 330 μs based on the high response characteristic design requirements of the high-speed motor. The effectiveness of this method has been verified by simulations and experiments. The proposed controller has a better ability to track the speed instruction in the case of mutations of the external load. It also has an excellent robustness to respond to the speed when the rotational inertia is changed. The authors design a system to test a high-speed motor whose rated power is 100 W and rated speed is 17,000 rpm. The results show that the method above can realise the high response and high precision servo control of high-speed motor without delay effectively.
- [Show abstract] [Hide abstract] ABSTRACT: Due to solve the shortcomings of the speed and position altering of the interpolation points near the extreme point and the junction point by filtering technology, the inference of moving-average of the position invariance was derived based on moving-average technology. By means of this inference, the shortcomings can be solved. And the method was scalable. It can achieve the acceleration of continuous, and jerk very easily and displacement for time of more-order differentiability of continuous. Thus the proposed algorithm can reduce the machining vibration. Finally, the implementation and experimental results were given in detail. The experimental results show the effectiveness and feasibility.
- [Show abstract] [Hide abstract] ABSTRACT: Condensin, a major non-histone protein complex on chromosomes, is responsible for the formation of rod-shaped chromosome in mitosis. A heterodimer composed of SMC2 (structural maintenance of chromosomes) and SMC4 subunits constitutes the core part of condensin. Although extensive studies have been done in yeast, fruit fly and Xenopus to uncover the mechanisms and molecular nature of SMC proteins, little is known about the complex in mammalian cells. We have conducted a series of experiments to unveil the nature of condensin complex in human chromosome formation. The results show that overexpression of the C-terminal domain of SMC subunits disturbs chromosome condensation, leading to formation of swollen chromosomes, while knockdown of SMC subunits severely disturbs mitotic chromosome formation, resulting in chromatin bridges between daughter cells and multiple nuclei in single cells. The salt extraction assay indicates that a fraction of the condensin complex is bound to chromatin in interphase, but most of the condensin bind to chromatin at the onset of mitosis. Thus, disturbance in condensin function or expression affects chromosome condensation and influences mitotic progression.
- [Show abstract] [Hide abstract] ABSTRACT: The functions of platelets and fibrinogen in protecting tumor cells from natural killer cytotoxicity have been discussed for more than 20 years. However, their exact roles and relationships in the process are still not clear. In this study, we show that tumor cells prefer to adhere to fibrinogen than to platelets, and fibrinogen can enhance the adhesion of tumor cells to platelets. Beta3 integrin plays an important role in the adhesion of B16F10 to platelets enhanced by fibrinogen. In the presence of thrombin, fibrinogen forms dense fibrin(ogen) layers around tumor cells. Tumor cells can induce platelets to aggregate and form thrombin. Platelets, as well as thrombin, can help fibrinogen protect tumor cells from lethal contact with natural killer cells and natural killer cytotoxicity. Hirudin, a specific inhibitor of thrombin, can reverse the effect of platelets on fibrinogen in blocking natural killer cytotoxicity. Our results suggest that fibrinogen helps platelets to adhere to tumor cells, and platelets in turn promote more fibrinogen to aggregate around tumor cells by forming thrombin. They facilitate each other in protecting tumor cells from natural killer cytotoxicity.
- [Show abstract] [Hide abstract] ABSTRACT: To investigate the correlation between subnucleolar structure and function, the precise distribution and configuration of nucleolar DNA during the cell cycle of Allium sativum were determined using the NAMA-Ur DNA-specific staining technique. We showed that nucleolar DNA is present in two forms: compacted chromatin clumps and a decondensed DNA cloud. The form of the DNA within the nucleolus varied greatly as the cell cycle progressed. During telophase, chromosomes extended into the prenucleolar body. In early G1 phase, DNA was only located in the fibrillar centers in the form of the condensed chromatin clump, while in mid-G1, S and G2 phases, the two forms of DNA were distributed in the fibrillar centers (FC) and dense fibrillar component (DFC). In prophase of mitosis, nucleolar DNA, along with FC and DFC, was linked into a network structure and condensed into a large chromatin clump. The area of the DNA cloud in the dense fibrillar component changed during different phases of the cell cycle. Our results demonstrated that the configuration of nucleolar DNA undergoes a series of decondensations and condensations during the cell cycle to fulfill the function of the nucleoli during the different phases.
- [Show abstract] [Hide abstract] ABSTRACT: By using the conventional electron microscopic technique and DNA specific cytochemical staining method (NAMA-Ur), we directly observed the arrangement and location of intranucleolar DNA in situ in wheat (Triticum aestivum L.) cells. The results showed that nucleolar DNA was found in Fibrillar Centers (FC), Dense Fibrillar Component (DFC) and the transitional region between FC and DFC. Moreover, the nucleolar DNA was distributed along the periphery of FC and by surrounding FC. We employed RNP preference staining (Bernhard staining) method to visualize the distribution and position of RNP in situ in nucleoli of wheat cells. The results directly showed that RNP mainly located in the transitional region between FC and DFC, in DFC and in Granular Component (GC). Moreover, RNP was irregularly distributed around FC. By employing anti-RNA/DNA hybrid antibodies, we directly and selectively labeled transcription sites of rRNA genes and testified that localization of transcription sites was not only in the transitional region between DFC and FC but also in DFC of nucleoli in wheat cells.
- [Show abstract] [Hide abstract] ABSTRACT: The distribution and configurations of nucleolar DNA in Pisum sativum L., Allium sativum L., Triticum aestivum L. were analyzed by specific cytochemical staining using NAMA-Ur. It has been observed that in the nucleoli of different plant species, the DNA occupied different positions in different areas, which may imply a different status and strategy of rDNA transcription. Our results showed irregular clumps of rDNA surrounding FCs in semi-circular formations in P. sativum and T. aestivum, indicating a regular pattern of rDNA distribution and supporting the helix model of rDNA configuration. The rDNA was condensed in some regions and uncondensed in others. Nucleolus-associated chromatin extended from outside the nucleolus to the periphery of the FCs via nucleolar channels, which suggests a possible origin for nucleolar DNA.
- [Show abstract] [Hide abstract] ABSTRACT: Lymphocyte recruitment onto inflamed tissues requires cells tethering to and rolling on vascular surfaces under flow. L-selectin is constitutively expressed on leukocytes to mediate the leukocytes' initial capture and subsequent rolling along the vessel. Apart from its adhesive function, engagement of L-selectin also results in cell activation, which is related to the completed signaling transduction. Here we show that ligation of L-selectin with its mAb increases c-Abl kinase activity, and that the activated c-Abl kinase can be recruited to and phosphorylate the cytoplasmic domain of L-selectin. In addition, the activated c-Abl kinase can regulate Zap70 kinase by increasing the phosphorylation of the Y319 site of Zap70 kinase and connect with Zap70 kinase through its SH2 domain. These results indicate that c-Abl kinase plays an important role in accepting and transferring the upstream activation events induced by L-selectin ligation.
- [Show abstract] [Hide abstract] ABSTRACT: Actin is an important protein in nucleus and has been implicated in transcription, however, the mechanism of its function in transcription is still not clear. In this article, we studied the role of actin in the regulation of human CSF1 gene transcription. Our results showed that nuclear actin stimulates the activity of CSF1 promoter, and the role in augmenting CSF1 gene transcription requires the formation of chromatin and Z-DNA structure. The ATP binding motifs of nuclear actin are essential for its function in regulating CSF1 gene transcription, and upon actin overexpression, there is an increase in the ATPase activity of nuclear proteins. Further investigation revealed that nuclear actin regulates CSF1 gene transcription in a BRG1 independent manner. Together, these original results have provided evidence for further understanding the mechanism of nuclear actin in regulating gene transcription.
- [Show abstract] [Hide abstract] ABSTRACT: c-Abl non-receptor tyrosine kinase has been implicated in many cellular processes including cell differentiation, stress response and regulating gene transcription. The mechanism by which c-Abl is involved in the regulation of gene transcription remains to be elucidated. In this study, we investigated the functions of c-Abl in the activation of p21 promoter. Our results showed that overexpression of c-Abl tyrosine kinase activated p21 promoter and endogenous p21 transcription in U2OS cells. We found that p53 is involved in the activation of p21 promoter by c-Abl, and integrative structure of p53 is required for regulating p21 transcription. In addition, the chromatin immunoprecipitation study demonstrated that c-Abl and p53 can be recruited to the region containing p53 binding site of p21 promoter, and c-Abl increases the DNA binding activity of p53 to the p21 promoter. Furthermore, not only the activation of p21 promoter but also the recruitment to p21 promoter by c-Abl is dependent on the interaction between c-Abl and p53 protein.
- [Show abstract] [Hide abstract] ABSTRACT: The presence of actin in the nucleus as well as its functions in various nuclear processes has been made clear in the past few years. Actin is known to be a part of chromatin-remodeling complexes BAF, which are required for maximal ATPase activity of the Brg1 component of the BAF complex. Moreover, the essential roles of actin in transcription mediated by RNA polymerases I, II and III have been demonstrated recently. On the other hand, a myosin I isoform, which contains a unique NH2-terminal extension for nucleus localization, has been specifically localized in nucleus. As is well known, myosin I is an actin-binding protein and plays an important role in various cellular activities. Though actin and nuclear myosin I (NM I) have been implicated to play distinct roles in gene expression, there has been no evidence for the actin-myosin interaction that might be involved in gene transcription mediated by RNA polymerase II (RNAP II). Here we show evidence that both actin and NM I are associated with RNAP II in nucleus by using co-localization and co-IP assays, and they may act together on gene transcription. The antibodies against β-actin or NM I can block RNA synthesis in a eukaryotic in vitro transcription system with template DNA comprising the promoter and the coding region of human autocrine motility factor receptor (hAMFR) gene; the antibodies pre-adsorbed with purified actin and NM I have no effect in transcriptional inhibition, indicating that the inhibition of transcription by anti-actin and anti-NM I is specific. These results suggest a direct involvement of actin-myosin complexes in regulating transcription. It also implicates that actin and NM I may co-exist in a same complex with RNAP II and the interaction of RNAP II with actin and NM I functions in the RNAP II-mediated transcription.
- [Show abstract] [Hide abstract] ABSTRACT: In order to get a deeper understanding of the relationship between nucleolus structure and its function, the dynamic change and derivation of FC (fibrillar center) and DFC (dense fibrillar component) through interphase were investigated in HeLa cells synchronized at the ultrastructural level. The results showed that there was a process of FC and DFC derivation in the nucleolus of HeLa cells during interphase. In G1 phase there were a few big FCs in the nucleolus of the HeLa cell. In S phase DFC around the FC got thickened and the configuration of the DFC changed. A lot of tiny FCs were derived from parts of the thickened DFC. We called the FC and DFC formed in G1 phase as primary FC (pri-FC) and primary DFC (pri-DFC) and the FC and DFC derived from the thickened pri-DFC as secondary FC (sec-FC) and secondary DFC (sec-DFC). In G2 phase sec-FC and sec-DFC were gradually separated from pri-DFC and scattered evenly in the nucleolus. Few large pri-FCs coexisted with numerous tiny sec-FCs in the nucleolus of HeLa cells in G2 phase. Based on the results of our observation, we suggest here a model of the dynamic change and the process of derivation of FC and DFC through interphase.
- [Show abstract] [Hide abstract] ABSTRACT: L-selectin is a cell adhesion molecule mediating the initial capture and subsequent rolling of leukocytes along the endothelial cells expressing L-selectin ligands. In addition to its action in adhesion, an intracellular signaling role for L-selectin has been recognized. Its cytoplasmic domain is involved in signal transduction following antibody crosslinking and in the regulation of receptor binding activity in response to intracellular signals. In this work, we demonstrated that L-selectin crosslinking led to F-actin polymerization and redistribution in human neutrophils. Using immuno-fluorescence microscopy, we observed that F-actin redistribution spatiotemporally related to the polarization of L-selectin. STI571, a specific inhibitor for cytoplasmic tyrosine kinase c-Abl, can inhibit F-actin polymerization and c-Abl redistribution in the activated neutrophils. Furthermore, we determined that c-Abl redistributed to the region where L-selectin polarized and associated with L-selectin in the activated neutrophils. The association between L-selectin and c-Abl was reduced by cytochalasin B. These results suggested that c-Abl was involved in the F-actin alteration triggered by L-selectin crosslinking in human neutrophils.
- [Show abstract] [Hide abstract] ABSTRACT: Several independent studies have indicated that tumor metastasis can be inhibited by chemically modified heparin with low anticoagulant activity in the different tumor models. The mechanism of inhibition by the heparin derivatives in part accounts for the interference of tumor cell-platelet interaction mediated by P-selectin. In the present study, we demonstrated that both heparin and chemically modified heparins inhibited the adhesion of nonsmall cell lung cancer (NSCLC) cells to P-selectin under static or flow conditions in vitro. Flow cytometric analysis with the heparan sulfate-specific monoclonal antibody revealed that both NSCLC cells express heparan sulfate-like proteoglycans. Furthermore, heparinase treatment impaired P-selectin binding, indicating that heparan sulfate-like proteoglycans on the tumor cell surface are implicated in the adhesion of NSCLC cells to P-selectin. These findings suggest that some chemically modified heparins with low anticoagulant activity may deserve further testing in the experimental NSCLC treatment protocols.
- [Show abstract] [Hide abstract] ABSTRACT: Accumulating evidence has suggested that one of the mechanisms by which heparin inhibits metastasis is by blocking the P-selectin-based interaction of platelets with tumor cells. Here we demonstrate that the sulfate groups at C6/N and especially C6, but not C2 and C3, of heparin play a critical role in P-selectin recognition and that 2-O,3-O-desulfated heparin can block P-selectin-mediated A375 human melanoma cell adhesion. Our findings show that chemical modification of heparin, especially 2-O,3-O-desulfation, may result in a therapeutic agent that is anti-metastatic because it blocks unwanted P-selectin-dependent adhesion but that lacks dose-limiting anticoagulant effects.
- [Show abstract] [Hide abstract] ABSTRACT: c-Abl tyrosine kinase, predominantly distributed in nucleus, has been implicated in many important cellular processes including the regulation of gene transcription. In this study, we showed that c-Abl promoted the transcription of c-fos gene, both exogenously and endogenously. The nuclear localization and tyrosine kinase activity of c-Abl were required for the activation of c-fos gene. c-Abl was associated with RNA polymerase II (RNAP II) in vivo and augmented the tyrosine phosphorylation of the largest subunit of RNAP II. In addition, c-Abl and RNAP II could be recruited to the region of c-fos promoter. The combined results suggest that c-Abl plays an important role in the transcriptional regulation of c-fos gene and the tyrosine phosphorylation of the largest subunit of RNAP II by c-Abl is involved in the regulating process.
Harbin Institute of TechnologyCharbin, Heilongjiang Sheng, China
Northeast Normal University
Hsin-ching, Jilin Sheng, China
- • The Institute of Genetics and Cytology
- • School of Life Sciences
Tianjin, Tianjin Shi, China
- College of Life Sciences
Changchun Normal UniversityHsin-ching, Jilin Sheng, China
Chinese Academy of Medical SciencesPeping, Beijing, China