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Wei L, Xiang G, Ma C, Jiang X, Dian S. Trajectory Tracking Control of Transformer Inspection Robot Using Distributed Model Predictive Control. Sensors (Basel) 2023; 23:9238. [PMID: 38005624 PMCID: PMC10674847 DOI: 10.3390/s23229238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 11/26/2023]
Abstract
To overcome the difficulty in tracking the trajectory of an inspection robot inside a transformer, this paper proposes a distributed model predictive control method. First, the kinematics and dynamics models of a robot in transformer oil are established based on the Lagrange equation. Then, by using the nonlinear model predictive control method and following the distributed control theory, the motion of a robot in transformer oil is decoupled into five independent subsystems. Based on this, a distributed model predictive control (DMPC) method is then developed. Finally, the simulation results indicate that a robot motion control system based on DMPC achieves high tracking accuracy and robustness with reduced computing complexity, and it provides an effective solution for the motion control of robots in narrow environments.
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Affiliation(s)
| | - Guofei Xiang
- College of Electrical Engineering, Sichuan University, Chengdu 610065, China; (L.W.); (C.M.); (X.J.); (S.D.)
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2
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Xiang G, Chai G, Lyu B, Li Z, Yin Y, Wang B, Pan Y, Shi M, Zhao L. Long-Term Results of Induction Chemotherapy for Esophageal Squamous Cell Carcinoma Receiving Concurrent Chemoradiotherapy. Int J Radiat Oncol Biol Phys 2023; 117:e351. [PMID: 37785216 DOI: 10.1016/j.ijrobp.2023.06.2425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
PURPOSE/OBJECTIVE(S) This study aimed to investigate the long-term clinical outcomes and toxicities of induction chemotherapy (IC) followed by concurrent chemoradiotherapy (CCRT) versus CCRT alone in patients with esophageal squamous cell carcinoma (ESCC). MATERIALS/METHODS Between 2008 and 2022, 271 ESCC patients who received definitive CCRT (IC followed by CCRT, n = 72; CCRT alone, n = 199) were enrolled. Radiotherapy technique included intensity modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT). Through a propensity score matched (PSM) method, 71 patients receiving IC and CCRT were matched 1:1 to patients who received CCRT alone, according to age, gender, performance status, tumor length, and pre-treatment TN stage. The Kaplan-Meier method and Cox proportional hazards model were applied to analyze survival and prognosis. RESULTS The IC + CCRT group had no improvement in 5-year overall survival (OS) rate (39.0% vs 29.3%, p = 0.360), recurrence-free survival (RFS) rate (39.0% vs 26.9%, p = 0.142), and distant metastasis-free survival (DMFS) rate (33.6% vs 27.2%, p = 0.515) compared with the CCRT group. The overall clinical response rate was 45.1% after IC in the IC + CCRT group. The IC responders (CR + PR + SD) group showed more favorable 5-year OS (41.7% vs. 14.3% vs. 29.3%, p < 0.001), RFS (41.7% vs. 14.3% vs. 26.9%, p < 0.001) and DMFS (37.3% vs. 0% vs. 27.2%, p < 0.001) compared with the IC non-responders (PD) group and the CCRT group. Besides, the 5-year OS rate (65.6% vs. 17.6% vs. 29.3%, p < 0.001), RFS rate (65.6% vs. 17.6% vs. 26.9%, p < 0.001), and DMFS rate (62.5% vs. 10.3% vs. 27.2%, p < 0.001) of the IC good responders (CR + PR) were significantly higher than that of the IC poor responders (SD + PD) and CCRT group. Multivariate analysis revealed that total radiotherapy time (≥ 49 days) and AJCC stage (Ⅲ/Ⅳ) were independent predictive factors of OS, RFS and DMFS. Besides, age was an independent predictive factor of DMFS. No significant difference was observed in the rates of grades 3-4 toxicities between both groups. CONCLUSION Our results showed the addition of IC to CCRT was not superior to CCRT in unselected ESCC patients, while IC responders could benefit from this regime without increase in toxicities.
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Affiliation(s)
- G Xiang
- Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi, China
| | - G Chai
- Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi, China
| | - B Lyu
- Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi, China
| | - Z Li
- Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi, China
| | - Y Yin
- Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi, China
| | - B Wang
- Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi, China
| | - Y Pan
- State Key Laboratory of Cancer Biology, National Clinical Research Center for Digestive Diseases and Xijing Hospital of Digestive Diseases, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi, China
| | - M Shi
- Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, China
| | - L Zhao
- Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
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Xiang G, Zhao L. Re-Irradiation for Locally Primary Recurrence in Esophageal Squamous Cell Carcinoma Treated with IMRT/VMAT. Int J Radiat Oncol Biol Phys 2023; 117:e351. [PMID: 37785218 DOI: 10.1016/j.ijrobp.2023.06.2426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
PURPOSE/OBJECTIVE(S) Locally primary recurrence of esophageal squamous cell carcinoma (ESCC) after definitive treatment has the potential for increasing overall survival with re-irradiation (Re-RT), especially with advanced technique. This study aimed to evaluate the efficacy and toxicities of Re-RT using intensity-modulated radiotherapy (IMRT)/volumetric modulated arc therapy (VMAT) for local primary-recurrence of ESCC. MATERIALS/METHODS A total of 130 ESCC patients with local primary-recurrence from Xijing hospital between 2008 and 2021 were enrolled and 30 patients underwent IMRT/VMAT based salvage Re-RT. Cox regression analysis was used to analyze the prognostic factors for overall survival (OS) and after recurrence survival (ARS). The toxicities of 30 patients receiving Re-RT were also assessed. RESULTS The median OS and ARS of the 130 recurrent patients were 21 months (1-164 months) and 6 months (1-142 months). The 1-, 2-, and 3-year OS rates were 81.5%, 39.2%, and 23.8%, respectively. Besides, the 1-, 2-, and 3-year ARS rates were 30.0%, 10%, and 6.2%. Multivariate analysis showed that Re-RT ± chemotherapy (p = 0.043) and chemotherapy alone (p < 0.001) and esophageal stents (p = 0.004) were independent prognostic factors for OS. The median OS of 30 patients treated with Re-RT were significantly better than that of 29 patients treated with chemotherapy (34.5 months vs. 22 months, p = 0.030). Among 30 ESCC patients treated with Re-RT, the median OS and ARS were 34.5 months (range 12-163 months) and 6 months (range 1-132 months), respectively. The recurrence-free interval (RFI) (> 12 months) and initial radiation dose (> 60 Gy) were significantly associated with improved OS. Radiation esophagitis (Grade 1-2) occurred in 16 patients and myelosuppression (Grade1-2) occurred in 10 patients. Grade 3 toxicities (radiation esophagitis and myelosuppression) were only 13.3%. There were no grade 4 toxicities. CONCLUSION Our results demonstrated that IMRT/VMAT-based Re-RT was an effective therapeutic option for ESCC patients with local primary-recurrence compared with chemotherapy alone or without any treatment. Re-RT had improved OS but unfavorable ARS.
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Affiliation(s)
- G Xiang
- Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi, China
| | - L Zhao
- Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, Shaanxi, China
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Xiang G, Dian S, Zhao N, Wang G. Semantic-Structure-Aware Multi-Level Information Fusion for Robust Global Orientation Optimization of Autonomous Mobile Robots. Sensors (Basel) 2023; 23:1125. [PMID: 36772164 PMCID: PMC9920800 DOI: 10.3390/s23031125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 01/12/2023] [Accepted: 01/13/2023] [Indexed: 06/18/2023]
Abstract
Multi-camera-based simultaneous localization and mapping (SLAM) has been widely applied in various mobile robots under uncertain or unknown environments to accomplish tasks autonomously. However, the conventional purely data-driven feature extraction methods cannot utilize the rich semantic information in the environment, which leads to the performance of the SLAM system being susceptible to various interferences. In this work, we present a semantic-aware multi-level information fusion scheme for robust global orientation estimation. Specifically, a visual semantic perception system based on the synthesized surround view image is proposed for the multi-eye surround vision system widely used in mobile robots, which is used to obtain the visual semantic information required for SLAM tasks. The original multi-eye image was first transformed to the synthesized surround view image, and the passable space was extracted with the help of the semantic segmentation network model as a mask for feature extraction; moreover, the hybrid edge information was extracted to effectively eliminate the distorted edges by further using the distortion characteristics of the reverse perspective projection process. Then, the hybrid semantic information was used for robust global orientation estimation; thus, better localization performance was obtained. The experiments on an intelligent vehicle, which was used for automated valet parking both in indoor and outdoor scenes, showed that the proposed hybrid multi-level information fusion method achieved at least a 10-percent improvement in comparison with other edge segmentation methods, the average orientation estimation error being between 1 and 2 degrees, much smaller than other methods, and the trajectory drift value of the proposed method was much smaller than that of other methods.
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Affiliation(s)
- Guofei Xiang
- College of Electrical Engineering, Sichuan University, Chengdu 610065, China
- National Key Laboratory of Special Vehicle Design and Manufacturing Integration Technology, Baotou 014031, China
| | - Songyi Dian
- College of Electrical Engineering, Sichuan University, Chengdu 610065, China
| | - Ning Zhao
- National Key Laboratory of Special Vehicle Design and Manufacturing Integration Technology, Baotou 014031, China
| | - Guodong Wang
- National Key Laboratory of Special Vehicle Design and Manufacturing Integration Technology, Baotou 014031, China
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Xiang G, Dian S, Du S, Lv Z. Variational Information Bottleneck Regularized Deep Reinforcement Learning for Efficient Robotic Skill Adaptation. Sensors (Basel) 2023; 23:762. [PMID: 36679561 PMCID: PMC9864208 DOI: 10.3390/s23020762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/03/2023] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
Deep Reinforcement Learning (DRL) algorithms have been widely studied for sequential decision-making problems, and substantial progress has been achieved, especially in autonomous robotic skill learning. However, it is always difficult to deploy DRL methods in practical safety-critical robot systems, since the training and deployment environment gap always exists, and this issue would become increasingly crucial due to the ever-changing environment. Aiming at efficiently robotic skill transferring in a dynamic environment, we present a meta-reinforcement learning algorithm based on a variational information bottleneck. More specifically, during the meta-training stage, the variational information bottleneck first has been applied to infer the complete basic tasks for the whole task space, then the maximum entropy regularized reinforcement learning framework has been used to learn the basic skills consistent with that of basic tasks. Once the training stage is completed, all of the tasks in the task space can be obtained by a nonlinear combination of the basic tasks, thus, the according skills to accomplish the tasks can also be obtained by some way of a combination of the basic skills. Empirical results on several highly nonlinear, high-dimensional robotic locomotion tasks show that the proposed variational information bottleneck regularized deep reinforcement learning algorithm can improve sample efficiency by 200-5000 times on new tasks. Furthermore, the proposed algorithm achieves substantial asymptotic performance improvement. The results indicate that the proposed meta-reinforcement learning framework makes a significant step forward to deploy the DRL-based algorithm to practical robot systems.
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Affiliation(s)
- Guofei Xiang
- College of Electrical Engineering, Sichuan University, Chengdu 610065, China
- National Key Laboratory of Special Vehicle Design and Manufacturing Integration Technology, Baotou 014031, China
| | - Songyi Dian
- College of Electrical Engineering, Sichuan University, Chengdu 610065, China
| | - Shaofeng Du
- National Key Laboratory of Special Vehicle Design and Manufacturing Integration Technology, Baotou 014031, China
| | - Zhonghui Lv
- National Key Laboratory of Special Vehicle Design and Manufacturing Integration Technology, Baotou 014031, China
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Fang H, Zhu Y, Dian S, Xiang G, Guo R, Li S. Robust tracking control for magnetic wheeled mobile robots using adaptive dynamic programming. ISA Trans 2022; 128:123-132. [PMID: 34756757 DOI: 10.1016/j.isatra.2021.10.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 10/18/2021] [Accepted: 10/18/2021] [Indexed: 06/13/2023]
Abstract
To handle the tracking control problem of the magnetic wheeled mobile robot (MWMR), this paper developed an online robust tracking control scheme by adaptive dynamic programming (ADP). The problem, that how to achieve optimal tracking control of continuous-time (CT) MWMR system with the time-varying unknown uncertainty, can be solved indirectly through matching the optimal tracking control of the associated nominal system . A single critic NN-based actor-critic structure is tailored for simpler controller architecture. By minimizing the Bellman error with gradient descending and least-squares updating laws, the critic NN weights can be optimized online. Thus the optimal cost function and the optimal control signal can be approximated with high precision. Using the Lyapunov stability theorem, the convergence of the critic NN weights, and the stability of the closed-loop system is provided. Simulations, in comparison with robust PD control and adaptive control, are presented to illustrate the effectiveness of the proposed tracking control method for the MWMR.
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Affiliation(s)
- Hongwei Fang
- College of Electrical Engineering, Sichuan University, Chengdu, 610065, China.
| | - Yuqi Zhu
- College of Electrical Engineering, Sichuan University, Chengdu, 610065, China.
| | - Songyi Dian
- College of Electrical Engineering, Sichuan University, Chengdu, 610065, China.
| | - Guofei Xiang
- College of Electrical Engineering, Sichuan University, Chengdu, 610065, China.
| | - Rui Guo
- State Grid Shandong Electric Power Company, Jinan, 250001, China.
| | - Shengchuan Li
- Electric Power Research Institute of State Grid Liaoning Electric Power Company, Ltd., Shenyang, 110006, China.
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7
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Wen Y, Xiang G, Xiong C, Yang Y, Zhang J. Isolated left subclavian artery with right aortic arch and bilateral ductus arteriosus: a challenging fetal diagnosis. Ultrasound Obstet Gynecol 2021; 57:500-501. [PMID: 32250490 DOI: 10.1002/uog.22039] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/20/2020] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Affiliation(s)
- Y Wen
- Department of Ultrasound, The Fifth People's Hospital of Chengdu, Chengdu, Sichuan Province, China
| | - G Xiang
- Department of Ultrasound, The Fifth People's Hospital of Chengdu, Chengdu, Sichuan Province, China
| | - C Xiong
- Department of Ultrasound, The Fifth People's Hospital of Chengdu, Chengdu, Sichuan Province, China
| | - Y Yang
- Department of Radiology, The Women and Children's Hospital of Chengdu, Chengdu, Sichuan Province, China
| | - J Zhang
- Department of Ultrasound, The Fifth People's Hospital of Chengdu, Chengdu, Sichuan Province, China
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Bao Z, Wang LJ, He K, Lin X, Yu T, Li J, Gong J, Xiang G. High expression of ACE2 in the human lung leads to the release of IL6 by suppressing cellular immunity: IL6 plays a key role in COVID-19. Eur Rev Med Pharmacol Sci 2021; 25:527-540. [PMID: 33506945 DOI: 10.26355/eurrev_202101_24425] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE The pathogenesis of coronavirus disease 2019 (COVID-19) remains clear, and no effective treatment exists. SARS-CoV-2 is the virus that causes COVID-19 and uses ACE2 as a cell receptor to invade human cells. Therefore, ACE2 is a key factor to analyze the SARS-CoV-2 infection mechanism. MATERIALS AND METHODS We included 9,783 sequencing results of different organs, analyzed the effects of different ACE2 expression patterns in organs and immune regulation. RESULTS We found that ACE2 expression was significantly increased in the lungs and digestive tract. The cellular immunity of individuals with elevated ACE2 expression is activated, whereas humoral immunity is dampened, leading to the release of many inflammatory factors dominated by IL6. Furthermore, by studying the sequencing results of SARS-CoV-2-infected and uninfected cells, IL6 was found to be an indicator of a significant increase in the number of infected cells. However, although patients with high expression of ACE2 will release many inflammatory factors dominated by IL6, cellular immunity in the colorectum is significantly activated. This effect may explain why individuals with SARS-CoV-2 infection have severe lung symptoms and digestion issues, which are important causes of milder symptoms. CONCLUSIONS This finding indicates that ACE2 and IL6 inhibitors have important value in COVID-19.
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Affiliation(s)
- Z Bao
- Department of General Surgery, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, P.R. China.
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Abstract
Reinforcement learning (RL) and imitation learning (IL), especially equipped with deep neural networks, have been widely studied for autonomous robotic skill acquisition and control tasks. However, these methods and their extensions require extensive environmental interactions during training, which greatly prevents them from being applied to real-world robots. To alleviate this problem, we present an efficient model-free off-policy actor-critic algorithm for robotic skill acquisition and continuous control, by fusing the task reward with a task-oriented guiding reward, which is formulated by leveraging few and imperfect expert demonstrations. In this framework, the agent can explore the environment more intentionally, thus sampling efficiency can be achieved; moreover, the agent can also exploit the experience more effectively, thereby substantially improved performance can be realized simultaneously. The empirical results on robotic locomotion tasks show that the proposed scheme can lower sample complexity by 2-10 times in contrast with the state-of-the-art baseline deep RL (DRL) algorithms, while achieving performance better than that of the expert. Furthermore, the proposed algorithm achieves significant improvement in both sampling efficiency and asymptotic performance on tasks with sparse and delayed reward, wherein those baseline DRL algorithms struggle to make progress. This takes a substantial step forward to implement these methods to acquire skills autonomously for real robots.
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10
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Xiang G, Su J. Interactive Natural Motion Planning for Robot Systems Based on Representation Space. Int J Soc Robot 2020. [DOI: 10.1007/s12369-019-00552-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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11
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Wen Y, Xiang G, Zhou L, Tong X. Left juxtaposition of atrial appendages with anatomically corrected malposition of great arteries: a challenging fetal diagnosis. Ultrasound Obstet Gynecol 2019; 54:560-562. [PMID: 31180602 DOI: 10.1002/uog.20369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/27/2019] [Accepted: 05/31/2019] [Indexed: 06/09/2023]
Affiliation(s)
- Y Wen
- Department of Ultrasound, The Fifth People's Hospital of Chengdu, Chengdu, China
| | - G Xiang
- Department of Ultrasound, The Fifth People's Hospital of Chengdu, Chengdu, China
| | - L Zhou
- Department of Ultrasound, The Children and Women's Hospital of Chengdu, Chengdu, China
| | - X Tong
- Department of Ultrasound, The Fifth People's Hospital of Chengdu, Chengdu, China
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Xiang G, Su J. A Heuristic algorithm for robustly stable generalized disturbance observer synthesis with closed loop consideration. ISA Trans 2019; 90:147-156. [PMID: 30773216 DOI: 10.1016/j.isatra.2019.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 12/18/2018] [Accepted: 01/07/2019] [Indexed: 06/09/2023]
Abstract
This paper investigate the problem of disturbance observer (DOB) based disturbance rejection control with closed loop performance guaranteed. A generalized DOB based control framework is presented. Specifically, the novel DOB framework if obtained by taking advantage of Youla factorization of a two degree-of-freedom controller in a nontraditional way. Closed loop analysis clarifies that generalized DOB inherits advantages of the traditional one, while mitigating its restrictions. Through appropriate reconfiguration, the Q-filter synthesizing is transformed into reduced-order controller designing. By taking advantage of the Kalman-Yakubovich-Popov (KYP) lemma and projection lemma, a two-stage heuristic algorithm is proposed: an initial full information controller is firstly established for the reconfigured system, which is used to heuristically obtain the reduced-order controller by alternately solving LMIs in the second stage. Finally, we illustrate the application of these results to minimum phase and non-minimum phase plants. Elaborated comparisons between the two-stage heuristic algorithm based generalized DOB and the state-of-art H∞ based DOB are conducted, the results verify the effectiveness and advantages.
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Affiliation(s)
- Guofei Xiang
- Dept. of Automation, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Jianbo Su
- Dept. of Automation, Shanghai Jiao Tong University, Shanghai, 200240, China.
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Li J, Chen Q, Wu H, Xie X, Dong Y, Xiang G, Li Y. Effects of Cyclopiazonic Acid on Pacemaker Current of Sinoatrial Nodal Pacemaker Cells. Heart Lung Circ 2018. [DOI: 10.1016/j.hlc.2018.06.265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Guo J, He Y, Mu L, Wang S, Weng Z, Xiang G, Boi FS. The role of Br in the selective synthesis of thin-walled carbon-nanotubes with micrometre-length Fe3C-filling, Fe3C tip-filled carbon nanotubes or empty carbon nanotubes by pyrolysis of ferrocene and (6-bromohexyl)ferrocene mixtures. RSC Adv 2015. [DOI: 10.1039/c5ra07494k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report an advanced chemical vapour deposition method which allows the synthesis-selection of thin walled carbon nanotubes filled with Fe3C, Fe3C tip-filled nanotubes or of empty nanotubes by addition of (6-bromohexyl)ferrocene to ferrocene.
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Affiliation(s)
- J. Guo
- College of Physical Science and Technology
- Sichuan University
- Chengdu
- China
| | - Y. He
- Analytical & Testing Center
- Sichuan University
- Chengdu
- China
| | - Lan Mu
- College of Physical Science and Technology
- Sichuan University
- Chengdu
- China
| | - S. Wang
- Analytical & Testing Center
- Sichuan University
- Chengdu
- China
| | - Zhichao Weng
- College of Physical Science and Technology
- Sichuan University
- Chengdu
- China
| | - G. Xiang
- College of Physical Science and Technology
- Sichuan University
- Chengdu
- China
| | - Filippo S. Boi
- College of Physical Science and Technology
- Sichuan University
- Chengdu
- China
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15
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Zhang J, Xiang G, Xiang L, Sun H. Serum uric acid is associated with arterial stiffness in men with newly diagnosed type 2 diabetes mellitus. J Endocrinol Invest 2014; 37:441-7. [PMID: 24682912 DOI: 10.1007/s40618-013-0034-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Accepted: 11/17/2013] [Indexed: 01/09/2023]
Abstract
BACKGROUND Increased serum uric acid levels and vascular atherosclerosis are very common in diabetes. However, few studies focused on the relationship between serum uric acid and aortic or peripheral arterial stiffness in newly diagnosed diabetic patients. This study investigated the association between serum uric acid levels and carotid-femoral pulse wave velocity (cfPWV) or carotid-radial (cr) PWV in male patients with newly diagnosed type 2 diabetes mellitus (T2DM). METHODS 106 male patients with newly diagnosed T2DM were recruited. cfPWV and crPWV as well as anthropometric parameters, blood pressure, serum uric acid, blood glucose, fasting insulin, C-reactive protein and blood lipids were measured. RESULTS The subjects were divided into low uric acid (UA) subgroup and high UA subgroup according to uric acid median. cfPWV and crPWV were significantly higher in high UA subgroup. Serum uric acid significantly correlated with cfPWV (r = 0.533, P < 0.001), crPWV (r = 0.334, P = 0.001), waist circumference (r = 0.350, P < 0.001), waist-to-hip ratio (r = 0.254, P = 0.009), fasting insulin (r = 0.432, P < 0.001), HOMA-IR (r = 0.173, P = 0.042), fasting blood glucose (r = -0.271, P = 0.005), haemoglobin A1c (r = -0.202, P = 0.038), and HDL-cholesterol (r = -0.267, P = 0.006) after correction for age. Stepwise multiple regressions showed that the independent determinants of cfPWV were serum uric acid, age, C-reactive protein, HDL-cholesterol, and smoking status. And the independent determinants of crPWV were serum uric acid, age, diastolic blood pressure, and HDL-cholesterol. CONCLUSIONS Serum uric acid is significantly associated with increased aortic and peripheral arterial stiffness in men with T2DM at the early stage.
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Affiliation(s)
- J Zhang
- Department of Endocrinology, Wuhan General Hospital of Guangzhou Command, Wuluo Road 627, Wuhan, 430070, Hubei, People's Republic of China,
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Xu J, Zhao L, Xiang G, Xu C. Relationship between autoantibody to the angiotensin II-1 receptor and cardiovascular manifestations of Graves' disease. Exp Clin Endocrinol Diabetes 2014; 122:254-8. [PMID: 24771012 DOI: 10.1055/s-0034-1370920] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To investigate the role of autoantibody against angiotensin II-1 receptor (AT1-AA) in patients with cardiovascular manifestations of Graves' disease (GD). METHODS The epitope of the second extracellular loop of AT1 receptor (165-191) was synthesized and used as antigens to screen the autoantibody by enzyme linked immunosorbent assay (ELISA). The patients with GD were divided into the patients with cardiovascular manifestations associated to GD (Group A, n=58) and the patients with GD not complicated by heart disease (Group B, n=60). 40 healthy subjects were included in the study (Group C, n=40). Echocardiography was performed and the differences of echocardiography parameters were compared between AT1-AA positive and negative groups in group A. Factors related to left heart enlargement were analyzed by multiple logistic regression. RESULTS (1) The frequency of AT1-AA in Group A (52.2%, 32/58) were significantly higher than those in Group B (16.7%, 10/60) and Group C (12.5%, 5/40) (all p<0.001). (2) There were no differences in the level of TGAb, TPOAb and TRAb between AT1-AA positive and negative groups in patients with GD (all p>0.05). (3) In patients with cardiovascular manifestations of GD, the ratios between left atrial and ventricular enlargement (LAE and LVE) were significantly higher in the AT1-AA positive group than in the AT1-AA negative group (68.8% vs. 26.9%, 62.5% vs. 23.1%, all p<0.01); the frequency of atrial fibrillation differed significantly between these 2 groups (53.1% vs. 19.2%, p<0.01). (4) Regression analysis demonstrated that the positive AT1-AA and course of GD were significantly correlated to the presence of LAE and LVE. CONCLUSIONS AT1-AA plays an important role in the pathogenesis of cardiovascular manifestations associated to GD. Especially, AT1-AA is involved in left cardiac dilatation of GD complicated by heart disease, which represents a cardio-vascular risk factor for GD patients.
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Affiliation(s)
- J Xu
- Wuhan Clinical Medicine College, Southern Medical University, Wuhan, China
| | - L Zhao
- Department of Endocrinology and metabolism, Wuhan General Hospital of Guangzhou Command, Wuhan, China
| | - G Xiang
- Department of Endocrinology and metabolism, Wuhan General Hospital of Guangzhou Command, Wuhan, China
| | - C Xu
- Department of Endocrinology and metabolism, Wuhan General Hospital of Guangzhou Command, Wuhan, China
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17
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Xiang G, Ferson S, Ginzburg L, Longpré L, Mayorga E, Kosheleva O. Data Anonymization that Leads to the Most Accurate Estimates of Statistical Characteristics: Fuzzy-Motivated Approach. Proc IFSA World Congr 2013:611-616. [PMID: 25187183 PMCID: PMC4150686 DOI: 10.1109/ifsa-nafips.2013.6608471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
To preserve privacy, the original data points (with exact values) are replaced by boxes containing each (inaccessible) data point. This privacy-motivated uncertainty leads to uncertainty in the statistical characteristics computed based on this data. In a previous paper, we described how to minimize this uncertainty under the assumption that we use the same standard statistical estimates for the desired characteristics. In this paper, we show that we can further decrease the resulting uncertainty if we allow fuzzy-motivated weighted estimates, and we explain how to optimally select the corresponding weights.
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Affiliation(s)
- G. Xiang
- Applied Biomathematics, 100 North Country Rd., Setauket, NY 11733, USA
| | - S. Ferson
- Applied Biomathematics, 100 North Country Rd., Setauket, NY 11733, USA
| | - L. Ginzburg
- Applied Biomathematics, 100 North Country Rd., Setauket, NY 11733, USA
| | - L. Longpré
- University of Texas at El Paso, 500 W. University, El Paso, TX 79968, USA
| | - E. Mayorga
- University of Texas at El Paso, 500 W. University, El Paso, TX 79968, USA
| | - O. Kosheleva
- University of Texas at El Paso, 500 W. University, El Paso, TX 79968, USA
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18
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Xiang G, Xiang L, Xiang L, Wang H, Dong J. Change of Plasma Osteoprotegerin and its Association with Endothelial Dysfunction before and after Exercise in Hashimoto’s Thyroiditis with Euthyroidism. Exp Clin Endocrinol Diabetes 2012; 120:529-34. [PMID: 23070830 DOI: 10.1055/s-0032-1323806] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- G. Xiang
- Department of Endocrinology, Wuhan General Hospital of Guangzhou Command, Wuhan, Hubei Province, P. R. China
| | - L. Xiang
- Department of Endocrinology, Wuhan General Hospital of Guangzhou Command, Wuhan, Hubei Province, P. R. China
| | - L. Xiang
- College of Life Science, Hubei University, Wuhan, Hubei Province, P. R. China
| | - H. Wang
- Department of Endocrinology, Wuhan General Hospital of Guangzhou Command, Wuhan, Hubei Province, P. R. China
| | - J. Dong
- Department of Endocrinology, Wuhan General Hospital of Guangzhou Command, Wuhan, Hubei Province, P. R. China
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19
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Stern NP, Ghosh S, Xiang G, Zhu M, Samarth N, Awschalom DD. Current-induced polarization and the spin Hall effect at room temperature. Phys Rev Lett 2006; 97:126603. [PMID: 17025989 DOI: 10.1103/physrevlett.97.126603] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Indexed: 05/12/2023]
Abstract
Electrically induced electron spin polarization is imaged in n-type ZnSe epilayers using Kerr rotation spectroscopy. Despite no evidence for an electrically induced internal magnetic field, current-induced in-plane spin polarization is observed with characteristic spin lifetimes that decrease with doping density. The spin Hall effect is also observed, indicated by an electrically induced out-of-plane spin polarization with opposite sign for spins accumulating on opposite edges of the sample. The spin Hall conductivity is estimated as 3+/-1.5 Omega(-1) m(-1)/|e| at 20 K, which is consistent with the extrinsic mechanism. Both the current-induced spin polarization and the spin Hall effect are observed at temperatures from 10 to 295 K.
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Affiliation(s)
- N P Stern
- Center for Spintronics and Quantum Computation, University of California-Santa Barbara, CA 93106, USA
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20
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Cumings J, Moore LS, Chou HT, Ku KC, Xiang G, Crooker SA, Samarth N, Goldhaber-Gordon D. Tunable anomalous Hall effect in a nonferromagnetic system. Phys Rev Lett 2006; 96:196404. [PMID: 16803118 DOI: 10.1103/physrevlett.96.196404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Indexed: 05/10/2023]
Abstract
We measure the low-field Hall resistivity of a magnetically doped two-dimensional electron gas as a function of temperature and electrically gated carrier density. Comparing these results with the carrier density extracted from Shubnikov-de Haas oscillations reveals an excess Hall resistivity that increases with decreasing temperature. This excess Hall resistivity qualitatively tracks the paramagnetic polarization of the sample, in analogy to the ferromagnetic anomalous Hall effect. The data are consistent with skew scattering of carriers by disorder near the crossover to localization.
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Affiliation(s)
- John Cumings
- Department of Physics, Stanford University, California 94305, USA
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21
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Kocher AA, Schuster MD, Bonaros N, Lietz K, Xiang G, Martens TP, Kurlansky PA, Sondermeijer H, Witkowski P, Boyle A, Homma S, Wang SF, Itescu S. Myocardial homing and neovascularization by human bone marrow angioblasts is regulated by IL-8/Gro CXC chemokines. J Mol Cell Cardiol 2006; 40:455-64. [PMID: 16438981 DOI: 10.1016/j.yjmcc.2005.11.013] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Revised: 11/22/2005] [Accepted: 11/30/2005] [Indexed: 11/18/2022]
Abstract
In the adult, new blood vessel formation can occur either through angiogenesis from pre-existing mature endothelium or vasculogenesis mediated by bone marrow-derived endothelial precursors. We recently isolated endothelial progenitor cells, or angioblasts, in human adult bone marrow which have selective migratory properties for ischemic tissues, including myocardium, to where they home and induce vasculogenesis. Here we show that myocardial production of the IL-8/Gro-alpha CXC chemokine family is significantly increased after acute ischemia, and that this provides a chemoattractant gradient for bone marrow-derived endothelial progenitors, or angioblasts. This chemokine-mediated homing of bone marrow angioblasts to the ischemic heart regulates their ability to induce myocardial neovascularization, protection against cardiomyocyte apoptosis, and functional cardiac recovery. Together, our results indicate that CXC chemokines play a central role in regulating vasculogenesis in the adult, and suggest that manipulation of interactions between chemokines and their receptors on autologous human bone marrow-derived angioblasts could augment neovascularization of ischemic myocardial tissue.
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Affiliation(s)
- A A Kocher
- Department of Surgery, Medicine, and Pathology, Columbia University, New York, USA.
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22
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Schuster MD, Kocher AA, Seki T, Martens TP, Xiang G, Homma S, Itescu S. Myocardial neovascularization by bone marrow angioblasts results in cardiomyocyte regeneration. Am J Physiol Heart Circ Physiol 2004; 287:H525-32. [PMID: 15277196 DOI: 10.1152/ajpheart.00058.2004] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The primary cardiac response to ischemic insult is cardiomyocyte hypertrophy, which initiates a genetic program culminating in apoptotic myocyte loss, progressive collagen replacement, and heart failure, a process termed cardiac remodeling. Although a few cardiomyocytes at the peri-infarct region can proliferate and regenerate after injury, no approaches are known to effectively induce endogenous cardiomyocytes to enter the cell cycle. We recently isolated, in human adult bone marrow, endothelial progenitor cells, or angioblasts, that migrate to ischemic myocardium, where they induce neovascularization and prevent myocardial remodeling. Here we show that increasing the number of angioblasts trafficking to the infarct zone results in dose-dependent neovascularization with development of progressively larger-sized capillaries. This results in sustained improvement in cardiac function by mechanisms involving protection against apoptosis and, strikingly, induction of proliferation/regeneration of endogenous cardiomyocytes. Our results suggest that agents that increase myocardial homing of bone marrow angioblasts could effectively induce endogenous cardiomyocytes to enter the cell cycle and improve functional cardiac recovery.
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Affiliation(s)
- M D Schuster
- Department of Surgery and Medicine, Columbia University, New York, New York 10032, USA
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23
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Xiang G, Schinzel R, Simm A, Münch G, Sebekova K, Kasper M, Niwa T, Schmitz C, Heidland A. Advanced glycation end products (AGEs)-induced expression of TGF-beta 1 is suppressed by a protease in the tubule cell line LLC-PK1. Nephrol Dial Transplant 2001; 16:1562-9. [PMID: 11477156 DOI: 10.1093/ndt/16.8.1562] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Advanced glycation end products (AGEs) are assumed to play a key role in diabetic nephropathy (DN). Since little is known about their action in tubule cells, we investigated in LLC-PK1 cells: (i) whether AGE-bovine serum albumin (AGE-BSA) affects cell proliferation and expression of transforming growth factor-beta (TGF-beta 1); and (ii) whether the AGE-induced effects can be modulated by trypsin due to interference with its binding proteins at the cell surface. METHODS Arrested cells were exposed to vehicle (control), AGE-BSA (19--76 microM) and BSA (38 microM) in the presence or absence of trypsin (0.625--5.0 microg/ml) (2.5 microg/ml) for 24 h. We evaluated cell proliferation by cell count and by [(3)H]thymidine incorporation, TGF-beta 1 expression by reverse transcription-polymerase chain reaction (RT-PCR), and TGF-beta 1 protein by ELISA. In addition, cell accumulation of AGEs was studied by immunohistochemical staining of the AGE imidazolone. RESULTS AGE-BSA inhibited [(3)H]thymidine incorporation, lowered cell number and increased cell protein content as well as TGF-beta 1 mRNA and protein as compared with control and BSA. Immunohistochemical staining revealed a marked intracellular accumulation of the AGE imidazolone. Co-incubation of AGE-BSA with trypsin ameliorated the impaired thymidine incorporation, the decreased cell count and the enhanced cell protein content. TGF-beta 1 overexpression was normalized, while TGF-beta 1 protein declined insignificantly. Intracellular imidazolone accumulation was strikingly suppressed. CONCLUSIONS In the tubule cell line LLC-PK1, AGE-BSA exerts an antiproliferative effect, most probably due to TGF-beta 1 overproduction. The co-administration of trypsin abrogated this alteration, very likely as a result of an interaction with AGE-binding protein(s), which is supported by the decreased intracellular AGE accumulation. These findings may be the starting point for the development of specific proteolytic enzymes to interfere with the interaction between AGEs and their receptors/binding proteins.
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Affiliation(s)
- G Xiang
- Department of Internal Medicine and Institute of Physiological Chemistry, University of Würzburg, Germany
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24
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Xiang G, Schinzel R, Simm A, Sebekova K, Heidland A. Advanced glycation end products impair protein turnover in LLC-PK1: amelioration by trypsin. Kidney Int Suppl 2001; 78:S53-7. [PMID: 11168983 DOI: 10.1046/j.1523-1755.2001.59780053.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Advanced glycation end products (AGEs) are assumed to play a key role in the pathogenesis of diabetic nephropathy (DN) and other diabetic complications. While AGEs have been shown to exert marked effects on mesangial and endothelial cells as well as on monocytes/macrophages, little is known about their effects on tubule cells. Therefore, we addressed the questions of (1) whether AGE-bovine serum albumin (AGE-BSA) impairs the protein metabolism in the tubule cells, and if so, (2) whether the AGE-induced effects are mediated via a protease sensitive mechanism. METHODS Arrested LLC-PK1 cells were exposed to a medium containing the vehicle (control, serum free), AGE-BSA (38 micromol/L), or BSA (38 micromol/L) in the presence or absence of trypsin (2.5 microg/mL) for 24 hours. We evaluated cell number, cell size, and cell protein content, as well as protein synthesis and protein degradation. RESULTS After an incubation period of 24 hours, AGE-BSA decreased the cell number to 84.5 +/- 5.5% of control and 82.5 +/- 5.6% of BSA-treated cells (P < 0.05). [3H]-thymidine incorporation declined to 66% of control (P < 0.05), while BSA was without any effect. The same AGE-BSA dose reduced protein degradation (P < 0.05) and stimulated total protein synthesis slightly, as determined by L-[14C]Phe incorporation into acidic-insoluble proteins. These effects resulted in a rise in cell protein content (AGE-BSA vs. control, 21.9 +/- 6.7%; AGE-BSA vs. BSA, 11.1 +/- 6.0%, P < 0.05) and cell volume (AGE-BSA vs. control 9.4 +/- 3.2%, AGE-BSA vs. BSA 18.4 +/- 3.7%, P < 0.05). Coincubation with AGE-BSA and trypsin was associated with an amelioration of all investigated parameters concerning cell number, cell proliferation, raised cell protein content, decreased protein degradation, and enhanced protein synthesis. CONCLUSION These data indicate that AGE-BSA impairs cell proliferation and protein turnover in LLC-PK1 cells with a consequent rise in cell protein. Since these alterations were abrogated by coincubation with trypsin, an interference of this serine protease with the AGE-binding proteins on cell surfaces is assumed.
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Affiliation(s)
- G Xiang
- Department of Internal Medicine, Institute of Physiological Chemistry, University of Würzburg, Würzburg, Germany
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25
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Xiang G, Xia B, He Y. [The relationship of Apo E2 and renal insufficiency lipid levels in NIDDM]. Zhonghua Yi Xue Za Zhi 1999; 79:339-41. [PMID: 11715472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
OBJECTIVE To study the relationship of ApoE2 and renal insufficiency, lipid levels in NIDDM patients. METHODS PCR/ASO probe technique was used to determine ApoE genotypes. 46 NIDDM patients with renal insufficiency and 84 NIDDM patients without renal insufficiency as well as 50 healthy individuals were selected. Of the patients with renal insufficiency, 10 belonged to ApoE2 and 38 to ApoE3/3. In addition, 57 NIDDM patients with normalbuminuria (6 with ApoE2, 51 with ApoE3/3) were selected from the 84 NIDDM patients without renal insufficiency. RESULTS Allele frequency was significantly higher in diabetic patients with renal insufficiency than in diabetic patients without renal insufficiency and in healthy individuals (P < 0.05). Tc, TG levels were significantly higher in ApoE2 group with renal insufficiency than in E3/3 group with renal insufficiency, ApoE3/3 and ApoE2 groups with normoal buminuria. HDL-c level was significantly lower in ApoE2 group with renal insufficiency than in other 3 groups. CONCLUSION ApoE2 is associated with renal insufficiency in NIDDM patients and that ApoE2 may be a factor that aggravates lipid abnormalities in NIDDM patients with renal insufficiency.
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Affiliation(s)
- G Xiang
- Department of Endocrinology, Guangzhou Army Wuhan General Hospital of PLA, Guangzhou 430070
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26
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Sebeková K, Schinzel R, Ling H, Simm A, Xiang G, Gekle M, Münch G, Vamvakas S, Heidland A. Advanced glycated albumin impairs protein degradation in the kidney proximal tubules cell line LLC-PK1. Cell Mol Biol (Noisy-le-grand) 1998; 44:1051-60. [PMID: 9846887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Advanced glycation end-products (AGEs) are assumed to play a major role in the genesis of diabetic nephropathy and other diabetic complications. We studied the potential effect of AGEs on protein turnover and lysosomal proteinase activities in LLC-PK1 cells, a pig kidney proximal tubules cell line. Advanced glycated bovine serum albumin (AGE-BSA) was used as a model of AGEs and its action was compared to that of nonglycated BSA. AGE-BSA but not BSA (50 micromol/l) induced a significant increase in cell volume (BSA: 4870.6 +/- 74.8 fl, AGE-BSA: 5718.0 +/- 20.7 fl, p<0.01). Protein degradation rate was decreased by 13.8% after 48 hrs. incubation with AGE-BSA (p<0.01) while protein synthesis increased by 19,1%, (p<0.01). After incubation with AGE-BSA but not BSA activities of lysosomal cathepsins (B, L+B and H) decreased in a time- and dose-dependent fashion. This decline was neither caused by a shift in lysosomal pH outside the optimal range for cathepsins, nor by a direct inhibitory effect of AGEs modified proteins or peptides but most probably by inhibition of cathepsin B expression as measured by RT-PCR. It is supposed that impaired protease activities participated in decreased protein breakdown and cell enlargement. For the first time our data provide the evidence that AGEs induce hypertrophy of LLC-PK1 cells due to decreased protein breakdown resulting from reduced lysosomal proteinase activities with a concomitant stimulation of protein synthesis.
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Affiliation(s)
- K Sebeková
- Clinic of Pharmacotherapy, Institute of Preventive and Clinical Medicine, Bratislava, Slovakia
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27
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St Clair A, Xiang G, McLaughlin LW. Synthesis and triplex forming properties of an acyclic N7-glycosylated guanine nucleoside. Nucleosides Nucleotides 1998; 17:925-37. [PMID: 9708332 DOI: 10.1080/07328319808003464] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A chiral acyclic nucleoside, one in which the ribose carbohydrate has been replaced with a glycerol-based linker, is prepared by glycosylating guanine at the N7-nitrogen. The stereochemically pure derivative is converted to a DMT-protected phosphoramidite for incorporation into DNA sequences. Sequence containing the acyclic N7-dG nucleoside are capable of forming DNA triplexes in which it is likely that the N1-H and N2-amino groups of the N7-dG are involved in recognition of the guanine base in G-C base pairs.
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Affiliation(s)
- A St Clair
- Department of Chemistry, Merkert Chemistry Center, Chestnut Hill, MA 02167, USA
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Heidland A, Schinzel R, Sebekova K, Xiang G, Münch G, Simm A. Advanced glycation endproducts and the kidney. Przegl Lek 1998; 55 Suppl 1:29-31. [PMID: 9857688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
Affiliation(s)
- A Heidland
- Dept. of Int. Med., Univ. of Würzburg, Germany
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Abstract
Five modified hammerhead ribozyme/substrate complexes have been prepared in which individual adenosine N3-nitrogens have been excised and replaced with carbon. The modified complexes were chemically synthesized with the substitution of a single 3-deazzaadenosine (c3A) base analogue for residues A6, A9, A13, A14, or A15.1. Steady-state kinetic analyses indicate that the cleavage efficiencies, as measured by kcat/K(M), for the c3A6, c3A9, and c3A14 complexes were only marginally reduced (< or = 5-fold) relative to the native complex. By comparison, the cleavage efficiencies for the c3A13 and c315.1 complexes were reduced by 9-fold and 55-fold, respectively. these reductions in cleavage efficiency are primarily a result of lower kcat values. Profiles of pH and cleavage rate suggest that the chemical cleavage step is the rate-limiting reaction for these complexes. These results suggest that the N3-nitrogen of the A13 residue and particularly the A15.1 residue in the hammerhead ribozyme/substrate complex are critical for transition state stabilization and efficient cleavage activity. We have additionally compared the locations of these critical functional groups, as well as those identified from other studies, with recent crystallographic analyses. In some cases, the critical functional groups are clustered around proposed metal binding sites and may reflect functional groups critical for binding the metal cofactor. In other cases, clusters of functional groups may form a network of hydrogen bonds necessary for transition state stabilization.
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Affiliation(s)
- S Bevers
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02167, USA
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30
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Xiang G, Bogacki R, McLaughlin LW. Use of a pyrimidine nucleoside that functions as a bidentate hydrogen bond donor for the recognition of isolated or contiguous G-C base pairs by oligonucleotide-directed triplex formation. Nucleic Acids Res 1996; 24:1963-70. [PMID: 8657581 PMCID: PMC145865 DOI: 10.1093/nar/24.10.1963] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Synthesis of the nucleoside building block of the 6-keto derivative of 2'-deoxy-5-methylcytidine (m5oxC) as an analog of an N3-protonated cytosine derivative is described. A series of 15mer oligonucleotides containing either four or six m5oxC residues has been prepared by chemical synthesis. Complexation of the 15 residue oligonucleotides with target 25mer duplexes results in DNA triplexes containing T-A-T and m5oxC-G-C base triplets. When the m5oxC-G-C base triplets are present in sequence positions that alternate with TAT base triplets, DNA triplexes are formed with Tm values that are pH independent in the range 6.4-8.5. A 25mer DNA duplex containing a series of five contiguous G-C base pairs cannot be effectively targeted with either m5C or M5oxC in the third strand. In the former case charge-charge repulsion effects likely lead to destabilization of the complex, while in the latter case ineffective base stacking may be to blame. However, if the m5C and M5oxC residues are present in the third strand in alternate sequence positions, then DNA triplexes can be formed with contiguous G-C targets even at pH 8.0.
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Affiliation(s)
- G Xiang
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02167, USA
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