TGF-β promotes pericyte-myofibroblast transition in subretinal fibrosis through the Smad2/3 and Akt/mTOR pathways

Zhao Zhenzhen,Zhang Yumeng,Zhang Chaoyang,Zhang Jingting,Luo Xueting,Qiu Qinghua,Luo Dawei,Zhang Jingfa 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Subretinal fibrosis remains a major obstacle to the management of neovascular age-related macular degeneration. Choroidal pericytes were found to be a significant source of subretinal fibrosis, but the underlying mechanisms of pericyte-myofibroblast transition (PMT) remain largely unknown. The goal of this study was to explore the role and potential mechanisms by which PMT contributes to subretinal fibrosis. Choroidal neovascularization (CNV) was induced by laser photocoagulation in transgenic mice with the collagen1α1-green fluorescent protein (Col1α1-GFP) reporter, and recombinant adeno-associated virus 2 (rAAV2)-mediated TGF-β2 (rAAV2-TGF-β2) was administered intravitreally to further induce PMT. Primary mouse choroidal GFP-positive pericytes were treated with TGF-β2 in combination with siRNAs targeting Smad2/3, the Akt inhibitor MK2206 or the mTOR inhibitor rapamycin to examine cell proliferation, migration, and differentiation into myofibroblasts. The involvement of the Akt/mTOR pathway in PMT in subretinal fibrosis was further investigated in vivo. Intraocular TGF-β2 overexpression induced GFP-positive pericyte infiltration and PMT in subretinal fibrosis, which was mimicked in vitro. Knockdown of Smad2/3 or inhibition of Akt/mTOR decreased cell proliferation, PMT and migration in primary mouse pericytes. Combined inhibition of Smad2/3 and mTOR showed synergistic effects on attenuating α-smooth muscle actin (α-SMA) expression and cell proliferation. In mice with laser-induced CNV, the administration of the Akt/mTOR inhibitors suppressed pericyte proliferation and alleviated the severity of subretinal fibrosis. Our results showed that PMT plays a pivotal role in subretinal fibrosis, which was induced by TGF-β2 through the Smad2/3 and Akt/mTOR pathways. Thus, inhibiting PMT may be a novel strategy for the treatment of subretinal fibrosis.

Thematic Progression Patterns in English Abstracts of Doctoral Dissertations by EFL Students

Zhenzhen Zhang,이보림 한국영어학회 2019 영어학 Vol.19 No.4

This study examines the use of thematic progression (TP) patterns in English abstracts of doctoral dissertations written by Korean and Chinese students in medical science. These EFL students’ abstracts are compared with an American university’s dissertation abstracts in the same field. The results of the mixed quantitative-qualitative analyses reveal that the three most preferred TP patterns in all three groups are exactly the same: simple linear pattern, constant Theme pattern, and constant Rheme pattern. However, the detailed uses of the three patterns vary slightly according to the groups. The EFL groups, Korean and Chinese writers, exhibit more similarities than differences with each other on their choices of TP patterns. When compared with the American control group, both EFL groups show deviations. Specifically, both EFL groups tend to overuse the alternative model. Additionally, the Chinese group also overuses the constant Theme pattern, which is known to disturb cohesion and coherence of writing. The results of a pilot study conducted to probe the reasons of these deviations suggest the writers’ native language influences. The results of this study also provide some pedagogical implications in terms of text organization for EFL academic writing.

Type synthesis of the fully-decoupled two-rotational and one-translational parallel mechanism

Yanbin Zhang,Xuemin Wei,Shuang Zhang,Zhenzhen Chang,Yaoguang Li 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

Type synthesis of parallel mechanism is regarded as the theoretical basis and source for the original innovation design of mechanical devices and robots. A new method for type synthesis of the fully-decoupled two-rotational and one-translational (2R1T) parallel mechanisms with three degrees of freedom is proposed in this paper. Based on the actuation wrench screw theory, the mathematical model mapping the input and output velocity vector space of the fully-decoupled 2R1T parallel mechanism is established. The actuation wrench screws and the actuated twist screws of the corresponding branches are derived according to the mathematic model. The forms of the unactuated screws are determined in terms of the reciprocal product theory. Structural synthesis of the branch chains is realized. Then type synthesis of parallel mechanisms is completed as well and lots of novel mechanisms are obtained. Finally, a 2RUPU-PU parallel mechanism synthesized is taken as an example to analyze its mobility and kinematics. Results show that the mechanism has two-rotational and onetranslational degrees of freedom and its Jacobian matrix is a diagonal matrix, i.e., it has the fully-decoupled kinematic characteristics. Therefore, the method proposed is correct and effective to synthesize the fully-decoupled 2R1T parallel mechanisms.

Lotus-Like Nano-Architectures Constructed from Self-Assembled Micelles via Hierarchical Assembly

Rongli Zhang,Xiaoxia Fan,Xiaofang Xu,Jingjing Lv,Zhenzhen Jin,Hui Hao,Cuige Zhang 한국고분자학회 2018 Macromolecular Research Vol.26 No.1

Dopamine modified γ-polyglutamic acid (γ-PGA-DA) copolymer and melamine (Mel) can self-assemble into Mel/γ-PGA-DA micelles via weak intermolecular interactions in aqueous solution containing small amount of methanol. When Mel/γ-PGA-DA micellar solution was cast on the surface of formvar stabilized with carbon support films, the lotus-like nano-architectures were formed on the surface of substrate via hierarchical assembly of micelles. The size of lotus-like nanoarchitectures was approximately 200 nm×500 nm. The possible driving forces for hierarchical assembly of micelles were the solution fluid and interaction between micelles. The hierarchical assembly of micelles was similar to the fractal aggregation of inorganic particles and a possible reason was discussed.

Research on the Technology of Alternative Continuous Wide Spectral Spatial Heterodyne Spectrometer

Wenli Zhang,Fengchun Tian,Zhenzhen Zhao,An Song,Li Zhang 한국광학회 2017 Current Optics and Photonics Vol.1 No.4

An innovative system for the alternative continuous wide spectral spatial heterodyne spectrometer (ACWSSHS)is proposed. The relationship between the ACWS-SHS and the wide spectral spatial heterodynespectrometer (WS-SHS) at the resolution limit, the spectral range, the grating diffraction efficiency and theinterference fringes contrast ratio has been analyzed theoretically. Through the comparison of the theoreticalanalysis and simulation results, it is found that the two systems for the WS-SHS and the ACWS-SHShave the same resolution limit and spectral range, which are  and , while in the ACWS-SHS systemthe critical diffraction efficiency of echelle grating is 68.39% and the critical contrast ratio of interferencefringes is 0.4135, which is much better than the performance of the WS-SHS system. Therefore, the ACWSSHSreduces the high requirements for the precision of equipment and expands the application field ofSHS effectively.

Visualizing Polymer Spherulites in 3D

Zhenzhen WEI,Pantea KAZEMI,Hina SABA,Goran UNGAR,Ruibin ZHANG 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

A Virtual-Queue based Backpressure Scheduling Algorithm for Heterogeneous Multi-Hop Wireless Networks

( Zhenzhen Jiao ),( Baoxian Zhang ),( Jun Zheng ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.12

Backpressure based scheduling has been considered as a promising technique for improving the throughput of a wide range of communication networks. However, this scheduling technique has not been well studied for heterogeneous wireless networks. In this paper, we propose a virtual-queue based backpressure scheduling (VQB) algorithm for heterogeneous multi-hop wireless networks. The VQB algorithm introduces a simple virtual queue for each flow at a node for backpressure scheduling, whose length depends on the cache size of the node. When calculating flow weights and making scheduling decisions, the length of a virtual queue is used instead of the length of a real queue. We theoretically prove that VQB is throughput-optimal. Simulation results show that the VQB algorithm significantly outperforms a classical backpressure scheduling algorithm in heterogeneous multi-hop wireless networks in terms of the packet delivery ratio, packet delivery time, and average sum of the queue lengths of all nodes per timeslot.

DTN Routing with Back-Pressure based Replica Distribution

Zhenzhen Jiao,Rui Tian,Baoxian Zhang,Cheng Li 한국통신학회 2014 Journal of communications and networks Vol.16 No.4

Replication routing can greatly improve the data deliveryperformance by enabling multiple replicas of the same packet tobe transmitted towards its destination simultaneously. It has beenstudied extensively recently and is now a widely accepted routingparadigm in delay tolerant networks (DTNs). However, in thisfield, the issue of how to maximize the utilization efficiency of limitedreplication quota in a resource-saving manner and thereforemaking replication routing to be more efficient in networks withlimited resources has not received enough attention. In this paper,we propose a DTN routing protocol with back-pressure basedreplica distribution. Our protocol models the replica distributionproblem from a resource allocation perspective and it utilizes theidea of back-pressure algorithm, which can be used for providingefficient network resource allocation for replication quota assignmentamong encountered nodes. Simulation results demonstratethat the proposed protocol significantly outperforms existing replicationrouting protocols in terms of packet delay and delivery ratio.

The ethics of COVID-19 clinical trials: New considerations in a controversial area

Zhenzhen Han,Junting Wang,Kai Zhang,Qilin Tang 한국한의학연구원 2020 Integrative Medicine Research Vol.9 No.3

DTN Routing with Back-Pressure based Replica Distribution

Jiao, Zhenzhen,Tian, Rui,Zhang, Baoxian,Li, Cheng The Korea Institute of Information and Commucation 2014 Journal of communications and networks Vol.16 No.4

Replication routing can greatly improve the data delivery performance by enabling multiple replicas of the same packet to be transmitted towards its destination simultaneously. It has been studied extensively recently and is now a widely accepted routing paradigm in delay tolerant networks (DTNs). However, in this field, the issue of how to maximize the utilization efficiency of limited replication quota in a resource-saving manner and therefore making replication routing to be more efficient in networks with limited resources has not received enough attention. In this paper, we propose a DTN routing protocol with back-pressure based replica distribution. Our protocol models the replica distribution problem from a resource allocation perspective and it utilizes the idea of back-pressure algorithm, which can be used for providing efficient network resource allocation for replication quota assignment among encountered nodes. Simulation results demonstrate that the proposed protocol significantly outperforms existing replication routing protocols in terms of packet delay and delivery ratio.