618 results on '"Ponnambalam, S"'
Search Results
302. Biologically Inspired Architecture for Spatiotemporal Learning of Mobile Robots
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Kleinmann, Ludmilla, Mertsching, Bärbel, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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303. Twin-Hull URRG Blimp Control for Low Altitude Surveillance Application
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Tan, Guan Yap, Arshad, Mohd Rizal, Kadir, Herdawatie Abdul, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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304. Cordless Cart Follower for Wheelchair User
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Abdullah Sani, Noridayu, Syed Hassan, Syed Sahal Nazli Alhady bin, Othman, W. A. F. W., Kaharuddin, Suardi bin, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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305. EMG Signal Based Human Stress Level Classification Using Wavelet Packet Transform
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Karthikeyan, P., Murugappan, M., Yaacob, Sazali, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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306. Investigation on Upper Limb’s Muscle Utilizing EMG Signal
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Jauw, Veronica Lestari, Parasuraman, S., Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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307. Kinematics and Kinetics Studies on Upper Extremity during Walking Frame Ambulation
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Tat, Choo Ching, Jauw, Veronica Lestari, Parasuraman, S., Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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308. Analysis of Electrocardiogram (ECG) Signals for Human Emotional Stress Classification
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Bong, Siao Zheng, Murugappan, M., Yaacob, Sazali, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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309. Van Der Pol Central Pattern Generator (VDP-CPG) Model for Quadruped Robot
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Jasni, Farahiyah, Shafie, Amir Akramin, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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310. A Study on Vehicle Lateral Motion Control Using DGPS/RTK
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Lee, Kwanghee, Bak, Jeong-Hyeon, Lee, Chul-Hee, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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311. Drag Analysis of URRG Vertical Profiler (UVP) Using Integration of Computational Fluid Dynamics (CFD) and Design of Experiments (DOE)
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Zakaria, Muzammer, Ishak, Syafizal, Arshad, Mohd Rizal, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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312. Waypoint Navigated Unmanned Aerial Vehicle Autopilot System
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Sooriyakumara, Chamira, Veera Ragavan, S., Madhavan, S., Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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313. Bond Graph Based Unified Modeling Framework for Aerial Service Robots
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Veera Ragavan, S., Madhavan, S., Ganapathy, Velappa, Shirinzadeh, Bijan, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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314. An Efficient Grid Based Navigation of Wheeled Mobile Robots Based on Visual Perception
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Yean, Yap Ping, Kuppan Chetty, R. M., Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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315. GUI Teaching Pendant Development for a 6 Axis Articulated Robot
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Kaluarachchi, Malaka Miyuranga, Annaz, Fawaz Yahya, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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316. UTHM HAND: Kinematics behind the Dexterous Anthropomorphic Robotic Hand
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Zaid, Amran Mohd, Yaqub, M. Atif, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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317. Real Time Mobile Robot Navigation of Virtually Created Environments
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Annaz, Fawaz Y., Saeed, Ahmed Hikmat, Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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318. SCARA Robot: Modeled, Simulated, and Virtual-Reality Verified
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Al Mashhadany, Yousif I., Ponnambalam, S. G., editor, Parkkinen, Jussi, editor, and Ramanathan, Kuppan Chetty, editor
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- 2012
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319. Solving fixed charge transportation problem with truck load constraint using metaheuristics.
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Balaji, A. N., Mukund Nilakantan, J., Nielsen, Izabela, Jawahar, N., and Ponnambalam, S. G.
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TRUCKING , *LOADING & unloading , *SHIPMENT of goods , *PHYSICAL distribution of goods , *MATERIALS handling - Abstract
Fixed charge transportation (FCT) problems addressed in literature assumed shipment between a source and a destination is fulfilled in a single lot. However, in reality the lot size may exceed the capacity of the carrier and hence the shipment needs to be executed by conducting more than one trip. This gives an increased fixed charge which is proportional to the number of trips performed. This paper proposes a special case of the FCT problem were the truck load constraint is considered and is referred as the fixed charge transportation problem with truck load constraints (FCT-TLC) problem. The objective considered in this problem is to minimize the total cost of transportation without violating the supply and demand constraints. The general FCT problem is classified as NP-hard and to solve this proposed problem with additional constraints, two metaheuristic algorithms are used. A Genetic Algorithm (GA) and a Simulated Annealing Algorithm (SAA) are proposed to solve the FCT-TLC problem and the performance of the algorithms is tested on twenty randomly generated problem instances. Detailed comparative study on the computational results obtained using GA and SAA are presented. Both metaheuristics show good results for solving the proposed problem. However, SAA outperformed GA for many problems with different truck load capacities. To test the performance of the proposed algorithms, comparison with approximate and lower bound solutions for the problem with a relaxed truck capacity constraint is also presented. [ABSTRACT FROM AUTHOR]
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- 2019
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320. CORA - a heuristic approach to machine-part cell formation in the presence of alternative process plans.
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Sowmiya, N., Srinivasa Gupta, N., Valarmathi, B., and Ponnambalam, S.
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MACHINING , *MANUFACTURING processes , *CUTTING (Materials) , *MACHINE tools , *ABRASIVE machining - Abstract
In this paper, a three-stage heuristic is proposed to solve the machine-part cell formation (MPCF) problem in which parts have alternative process plans, commonly known as the generalized group technology problem. In the first stage, the best process plan (part route) for each part is selected using the proposed route rank index (RRI), a ranking measure calculated from the correlation among the process plans (CoRa - Correlation based ranking). In the second stage, machine-part cells are identified with an objective to maximize the grouping efficacy. A fine-tuning module validates the covering set in the third stage. Computational performance of the proposed heuristic on a set of generalized group technology dataset available in the literature is presented. The process plans identified by CORA resulted in a higher grouping efficacy for 25% of the test instances and for the other test instances the grouping efficacy achieved was as good as the best results reported in literature. [ABSTRACT FROM AUTHOR]
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- 2017
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321. An elitist strategy genetic algorithm for integrated layout design.
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Jerin Leno, I., Saravana Sankar, S., Victor Raj, M., and Ponnambalam, S.
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STRATEGIC planning , *GENETIC algorithms , *MANUFACTURING processes , *PRODUCT design , *MATERIALS handling , *PRODUCT quality , *INDUSTRIAL costs - Abstract
While designing the layout of any manufacturing organizations, the primary objective is to decide an optimal arrangement of their departments (machines or cells) in a two-dimensional shop floor (facility) satisfying desired objectives, which is termed facility layout problem (FLP). In traditional layout design philosophy, the inter-cell layout and flow path layout design of material handling system (MHS) was carried out step by step in a sequential manner. This results in sub-optimal solutions for FLP. In this paper, an integrated approach is adopted to design the inter-cell layout and the flow path layout of MHS simultaneously. The quality of the final layout is evaluated by minimizing the weighted sum of two distance-based cost objectives namely, (1) total material handling cost. (2) Distance-weighted cost of total closeness rating score. Sequence-pair (SP) representation is used for layout encoding. The translation from SP to layout is efficiently done by longest common subsequence methodology. Due to NP-hard nature of the proposed problem, an elitist strategy genetic algorithm (ESGA) is developed and tested with three test problem instances available in the literature. It is found that the proposed ESGA algorithm is able to produce the best solutions consistently, twice faster than the standard GA for the test problem instances. [ABSTRACT FROM AUTHOR]
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- 2013
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322. A combinatorial in silico and cellular approach to identify a new class of compounds that target VEGFR2 receptor tyrosine kinase activity and angiogenesis.
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Kankanala, J, Latham, AM, Johnson, AP, Homer-Vanniasinkam, S, Fishwick, CWG, and Ponnambalam, S
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CANCER treatment , *COMBINATORICS , *TARGETED drug delivery , *PROTEIN-tyrosine kinases , *NEOVASCULARIZATION , *VASCULAR endothelial growth factor receptors , *BIOLOGICAL assay - Abstract
BACKGROUND AND PURPOSE Vascular endothelial growth factor receptor 2 (VEGFR2) is an attractive therapeutic target for the treatment of diseases such as cancer. Small-molecule VEGFR2 inhibitors of a variety of chemical classes are currently under development or in clinical use. In this study, we describe the de novo design of a new generation pyrazole-based molecule (JK-P3) that targets VEGFR2 kinase activity and angiogenesis. EXPERIMENTAL APPROACH JK-P compound series were designed using de novo structure-based identification methods. Compounds were tested in an in vitro VEGFR2 kinase assay. Using primary endothelial cells, JK-P compounds were assessed for their ability to inhibit VEGF-A-stimulated VEGFR2 activation and intracellular signalling. We tested these compounds in cell migration, proliferation and angiogenesis assays. KEY RESULTS JK-P3 and JK-P5 were predicted to bind the VEGFR2 kinase domain with high affinity, and both compounds showed pronounced inhibition of endogenous VEGFR2 kinase activity in primary human endothelial cells. Only JK-P3 inhibited VEGF-A-stimulated VEGFR2 activation and intracellular signalling. Interestingly, JK-P3 inhibited endothelial monolayer wound closure and angiogenesis but not endothelial cell proliferation. Both compounds inhibited fibroblast growth factor receptor kinase activity in vitro, but not basic fibroblast growth factor-mediated signalling in endothelial cells. CONCLUSIONS AND IMPLICATIONS This is the first report that describes an anti-angiogenic inhibitor based on such a pyrazole core. Using a de novo structure-based identification approach is an attractive method to aid such drug discovery. These results thus provide an important basis for the development of multi-tyrosine kinase inhibitors for clinical use in the near future. [ABSTRACT FROM AUTHOR]
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- 2012
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323. Use of Affimer technology for inhibition of α2-antiplasmin and enhancement of fibrinolysis.
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Pechlivani N, Alsayejh B, Almutairi M, Simmons K, Gaule T, Phoenix F, Kietsiriroje N, Ponnambalam S, Duval C, Ariëns RAS, Tiede C, Tomlinson DC, and Ajjan RA
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- Humans, Diabetes Mellitus, Type 2 metabolism, Diabetes Mellitus, Type 2 drug therapy, Cardiovascular Diseases metabolism, Cardiovascular Diseases etiology, Fibrinolysis drug effects, alpha-2-Antiplasmin metabolism
- Abstract
Abstract: Hypofibrinolysis is a documented abnormality in conditions with high risk of vascular occlusion. A key inhibitor of fibrinolysis is α2-antiplasmin (α2AP), and we hypothesize that the Affimer technology, comprising small conformational proteins with 2 9-amino-acid variable regions, can be used to modulate α2AP activity and facilitate fibrinolysis. Using a phage display system, a library of Affimers was screened against α2AP. A total of 28 α2AP-specific Affimers were isolated, of which 1, termed Affimer A11, inhibited protein function and enhanced fibrinolysis. Affimer A11 displayed a monomeric form and consistently reduced the lysis time of clots made from plasma samples of individuals with type 2 diabetes mellitus (n = 15; from 150.8 ± 100.9 to 109.8 ± 104.8 minutes) and those with cardiovascular disease (n = 15; 117.6 ± 40.6 to 79.7 ± 33.3 minutes; P < .01 for both groups). The effects of A11 on fibrinolysis were maintained when clots were made from whole blood samples. Mechanistic studies demonstrated that A11 did not affect clot structure or interfere with the incorporation of α2AP into fibrin networks but significantly enhanced plasmin activity and accelerated plasmin generation. Affimer A11 reduced α2AP binding to plasmin(ogen), whereas molecular modeling demonstrated interactions with α2AP in an area responsible for binding to plasminogen, explaining the effects on both plasmin activity and generation. Affimer A11, at 0.15 to 0.60 mg/mL, had the ability to bind 70% to 90% of plasma α2AP. In conclusion, we demonstrate that Affimers are viable tools for inhibiting α2AP function and facilitating fibrinolysis, making them potential future therapeutic agents to reduce thrombosis risk., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)
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- 2025
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324. AMPK associates with and causes fragmentation of the Golgi by phosphorylating the guanine nucleotide exchange factor GBF1.
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Freemantle JB, Towler MC, Hudson ER, Macartney T, Zwirek M, Liu DJK, Pan DA, Ponnambalam S, and Hardie DG
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- Humans, Phosphorylation, HeLa Cells, ADP-Ribosylation Factor 1 metabolism, ADP-Ribosylation Factor 1 genetics, HEK293 Cells, Protein Transport, Pyridines, Quinolines, Golgi Apparatus metabolism, Guanine Nucleotide Exchange Factors metabolism, Guanine Nucleotide Exchange Factors genetics, AMP-Activated Protein Kinases metabolism, AMP-Activated Protein Kinases genetics
- Abstract
AMP-activated protein kinase (AMPK) is an energy sensor that regulates cellular functions in response to changes in energy availability. However, whether AMPK activity is spatially regulated, and the implications for cell function, have been unclear. We now report that AMPK associates with the Golgi, and that its activation by two specific pharmacological activators leads to Golgi fragmentation similar to that caused by the antibiotic Golgicide A, an inhibitor of Golgi-specific Brefeldin A resistance factor-1 (GBF1), a guanine nucleotide exchange factor that targets ADP-ribosylation factor 1 (ARF1). Golgi fragmentation in response to AMPK activators is lost in cells carrying gene knockouts of AMPK-α subunits. AMPK has been previously reported to phosphorylate GBF1 at residue Thr1337, and its activation causes phosphorylation at that residue. Importantly, Golgi disassembly upon AMPK activation is blocked in cells expressing a non-phosphorylatable GBF1-T1337A mutant generated by gene editing. Furthermore, the trafficking of a plasma membrane-targeted protein through the Golgi complex is delayed by AMPK activation. Our findings provide a mechanism to link AMPK activation during cellular energy stress to downregulation of protein trafficking involving the Golgi., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)
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- 2024
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325. Virtual high throughput screening of natural peptides against ErbB1 and ErbB2 to identify potential inhibitors for cancer chemotherapy.
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Patnaik SK, Ayyamperumal S, Jade D, Palathoti N, Akey KS, Jupudi S, Harrison MA, Ponnambalam S, Mj N, and Mjn C
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- Humans, Protein Binding, Neoplasms drug therapy, Neoplasms metabolism, Protein Kinase Inhibitors chemistry, Protein Kinase Inhibitors pharmacology, Thermodynamics, Receptor, ErbB-2 antagonists & inhibitors, Receptor, ErbB-2 metabolism, Antineoplastic Agents pharmacology, Antineoplastic Agents chemistry, Molecular Dynamics Simulation, ErbB Receptors antagonists & inhibitors, ErbB Receptors metabolism, Molecular Docking Simulation, Peptides chemistry, Peptides pharmacology, High-Throughput Screening Assays methods
- Abstract
Human epidermal growth factor receptors (EGFR), namely ErbB1/HER1, ErbB2/HER2/neu, ErbB3/HER3, and ErbB4/HER4, the trans-membrane family of tyrosine kinase receptors, are overexpressed in many types of cancers. These receptors play an important role in cell proliferation, differentiation, invasion, metastasis and angiogenesis including unregulated activation of cancer cells. Overexpression of ErbB1 and ErbB2 that occurs in several types of cancers is associated with poor prognosis leading to resistance to ErbB1-directed therapies. In this connection, promising strategy to overcome the disadvantages of the existing chemotherapeutic drugs is the use of short peptides as anticancer agents. In the present study, we have performed virtual high throughput screening of natural peptides against ErbB1 and ErbB2 to identify potential dual inhibitors and identified five inhibitors based on their binding affinities, ADMET analysis, MD simulation studies and calculation of free energy of binding. These natural peptides could be further exploited for developing drugs for treating cancer.Communicated by Ramaswamy H. Sarma.
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- 2024
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326. In-silico prediction, characterization, molecular docking and dynamic simulation studies for screening potential fungicides against leaf rust of Triticum aestivum .
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Gosavi G, Jade D, Ponnambalam S, Harrison MA, and Zhou H
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- Basidiomycota, Binding Sites, Puccinia chemistry, Protein Binding, Plant Leaves microbiology, Plant Leaves chemistry, Plant Leaves metabolism, Computer Simulation, Triticum microbiology, Molecular Docking Simulation, Fungicides, Industrial chemistry, Fungicides, Industrial pharmacology, Fungicides, Industrial metabolism, Molecular Dynamics Simulation, Plant Diseases microbiology
- Abstract
Triticum aestivum is an important crop worldwide, which is a large source of food grain. T.aestivum demands on developed countries will grow every year, this increase in the demand is profoundly serious especially in the light climate change which would lead to a 29% reduction in final productivity. Rust fungus attacks the T.aestivum , specifically newly planted T.aestivum plants, which block the vascular system, stun, and finally damage grain and tillers. In present study we predict the 3D structure then find the binding pocket and conserved domains for MAPkinase-1 of Puccinia triticina . After that, screen the FungiPAD, PubChem, NPAtlas databases by physicochemical properties, docking, clustering, ADME (Absorption, distribution, metabolism, and excretion) and PAINS (pan assay interference compounds) filter analysis. Through this screening process screen the nine compounds, which are benzovindiflupyr, furametpyr, isopyrazam, fenaminstrobin, and flumorph from Fungicide database: zoxamide, vinclozolin, pentachloronitrobenzene, and dithianon from PubChem database, based on the binding energy, clustering, ADME and PAINS analysis. All these nine compounds bind in the same pocket and show the same pattern of interaction. Among these nine compounds, select the two compounds (PubChem:122087 (-6.96 kcal/mol) and FDBD02904 (-8.62 kcal/mol)) based on binding energy for 100 ns MD simulation and free energy calculation. MD simulation shows stability throughout the simulation, and it shows the sable interaction when compounds bind to the MAPKinase 1 protein which may help to protein kinase pathways in plant defense response. This result helps to design alternative fungicide against the wheat rust disease.Communicated by Ramaswamy H. Sarma.
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- 2024
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327. "Affimer" synthetic protein scaffolds block oxidized LDL binding to the LOX-1 scavenger receptor and inhibit ERK1/2 activation.
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Roper BWR, Tiede C, Abdul-Zani I, Cuthbert GA, Jade D, Al-Aufi A, Critchley WR, Saikia Q, Homer-Vanniasinkam S, Sawamura T, McPherson MJ, Harrison MA, Tomlinson DC, and Ponnambalam S
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- Humans, HEK293 Cells, Lipoproteins, LDL metabolism, Receptors, Scavenger metabolism, Lectins metabolism, Scavenger Receptors, Class E genetics, Scavenger Receptors, Class E chemistry, Scavenger Receptors, Class E metabolism, MAP Kinase Signaling System
- Abstract
In multicellular organisms, a variety of lipid-protein particles control the systemic flow of triacylglycerides, cholesterol, and fatty acids between cells in different tissues. The chemical modification by oxidation of these particles can trigger pathological responses, mediated by a group of membrane proteins termed scavenger receptors. The lectin-like oxidized low-density lipoprotein (LOX-1) scavenger receptor binds to oxidized low-density lipoprotein (oxLDL) and mediates both signaling and trafficking outcomes. Here, we identified five synthetic proteins termed Affimers from a phage display library, each capable of binding recombinant LOX-1 extracellular (oxLDL-binding) domain with high specificity. These Affimers, based on a phytocystatin scaffold with loop regions of variable sequence, were able to bind to the plasma membrane of HEK293T cells exclusively when human LOX-1 was expressed. Binding and uptake of fluorescently labeled oxLDL by the LOX-1-expressing cell model was inhibited with subnanomolar potency by all 5 Affimers. ERK1/2 activation, stimulated by oxLDL binding to LOX-1, was also significantly inhibited (p < 0.01) by preincubation with LOX-1-specific Affimers, but these Affimers had no direct agonistic effect. Molecular modeling indicated that the LOX-1-specific Affimers bound predominantly via their variable loop regions to the surface of the LOX-1 lectin-like domain that contains a distinctive arrangement of arginine residues previously implicated in oxLDL binding, involving interactions with both subunits of the native, stable scavenger receptor homodimer. These data provide a new class of synthetic tools to probe and potentially modulate the oxLDL/LOX-1 interaction that plays an important role in vascular disease., Competing Interests: Conflicts of interest M. J. M. and D. C. T. are named inventors of the Affimer technology and this is filed under U.S. patent number #10,844,370 assigned to the University of Leeds on “Scaffold proteins derived from plant cystatins”., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)
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- 2023
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328. A research-led flexible cell biology practical for biological sciences undergraduate and postgraduate degree courses.
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Divan A, Alzahrani A, Shaik F, Mitchell J, Harrison MA, Odell A, and Ponnambalam S
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- Humans, Students, Curriculum, Biochemistry education, Laboratories, Biological Science Disciplines education
- Abstract
A challenge in the pandemic era is to implement effective but flexible practical teaching for biological sciences courses. Such teaching needs to deliver conceptual, analytical and practical skills training while having the option to rapidly respond to health and safety issues, local regulations, staff and student concerns. In this paper, we describe a set of cell biology practicals (mini-project) that meets many of these requirements and provides flexibility in providing skills training both through online and in practical laboratory environments. We have used a human adenocarcinoma cell line A431 stably transfected with a fluorescent cell cycle reporter as a biological model to deliver training through discrete work packages encompassing cell culture, fluorescence microscopy, biochemistry and statistics. How such work packages can be modified to, an online format either partially or completely is also described. Furthermore, the activities can be adapted for teaching both undergraduate and postgraduate level courses to ensure effective skills training which is applicable to a wide range of biological degree programs and levels of study., (© 2023 The Authors. Biochemistry and Molecular Biology Education published by Wiley Periodicals LLC on behalf of International Union of Biochemistry and Molecular Biology.)
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- 2023
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329. The E2 ubiquitin-conjugating enzymes UBE2D1 and UBE2D2 regulate VEGFR2 dynamics and endothelial function.
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Critchley WR, Smith GA, Zachary IC, Harrison MA, and Ponnambalam S
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- Humans, Vascular Endothelial Growth Factor A, Vascular Endothelial Growth Factor Receptor-2 genetics, Ubiquitination, Ubiquitin-Conjugating Enzymes genetics, Endothelial Cells
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Vascular endothelial growth factor receptor 2 (VEGFR2, encoded by KDR) regulates endothelial function and angiogenesis. VEGFR2 undergoes ubiquitination that programs this receptor for trafficking and proteolysis, but the ubiquitin-modifying enzymes involved are ill-defined. Herein, we used a reverse genetics screen for the human E2 family of ubiquitin-conjugating enzymes to identify gene products that regulate VEGFR2 ubiquitination and proteolysis. We found that depletion of either UBE2D1 or UBE2D2 in endothelial cells caused a rise in steady-state VEGFR2 levels. This rise in plasma membrane VEGFR2 levels impacted on VEGF-A-stimulated signalling, with increased activation of canonical MAPK, phospholipase Cγ1 and Akt pathways. Analysis of biosynthetic VEGFR2 is consistent with a role for UBE2D enzymes in influencing plasma membrane VEGFR2 levels. Cell-surface-specific biotinylation and recycling studies showed an increase in VEGFR2 recycling to the plasma membrane upon reduction in UBE2D levels. Depletion of either UBE2D1 or UBE2D2 stimulated endothelial tubulogenesis, which is consistent with increased VEGFR2 plasma membrane levels promoting the cellular response to exogenous VEGF-A. Our studies identify a key role for UBE2D1 and UBE2D2 in regulating VEGFR2 function in angiogenesis., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)
- Published
- 2023
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330. VEGFR endocytosis: Implications for angiogenesis.
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Saikia Q, Reeve H, Alzahrani A, Critchley WR, Zeqiraj E, Divan A, Harrison MA, and Ponnambalam S
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- Humans, Signal Transduction, Lymphangiogenesis physiology, Endocytosis, Vascular Endothelial Growth Factor A metabolism, Receptors, Vascular Endothelial Growth Factor metabolism
- Abstract
The binding of vascular endothelial growth factor (VEGF) superfamily to VEGF receptor tyrosine kinases (VEGFRs) and co-receptors regulates vasculogenesis, angiogenesis and lymphangiogenesis. A recurring theme is that dysfunction in VEGF signaling promotes pathological angiogenesis, an important feature of cancer and pro-inflammatory disease states. Endocytosis of basal (resting) or activated VEGFRs facilitates signal attenuation and endothelial quiescence. However, increasing evidence suggest that activated VEGFRs can continue to signal from intracellular compartments such as endosomes. In this chapter, we focus on the evolving link between VEGFR endocytosis, signaling and turnover and the implications for angiogenesis. There is much interest in how such understanding of VEGFR dynamics can be harnessed therapeutically for a wide range of human disease states., (Copyright © 2023 Elsevier Inc. All rights reserved.)
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- 2023
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331. Identification of FDA-approved drugs against SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) through computational virtual screening.
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Jade D, Alzahrani A, Critchley W, Ponnambalam S, and Harrison MA
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The SARS-CoV-2 coronavirus is responsible for the COVID-19 outbreak, which overwhelmed millions of people worldwide; hence, there is an urgency to identify appropriate antiviral drugs. This study focuses on screening compounds that inhibit RNA-dependent RNA-polymerase (RdRp) essential for RNA synthesis required for replication of positive-strand RNA viruses. Computational screening against RdRp using Food and Drug Administration (FDA)-approved drugs identified ten prominent compounds with binding energies of more than - 10.00 kcal/mol, each a potential inhibitor of RdRp. These compounds' binding energy is comparable to known RdRp inhibitors remdesivir (IC50 = 10.09 μM, SI = 4.96) and molnupiravir (EC50 = 0.67 - 2.66 µM) and 0.32-2.03 µM). Remdesivir and molnupiravir have been tested in clinical trial and remain authorized for emergency use in the treatment of COVID-19. In docking simulations, selected compounds are bound to the substrate-binding pocket of RdRp and showed hydrophobic and hydrogen bond interaction. For molecular dynamics simulation, capmatinib, pralsetinib, ponatinib, and tedizolid phosphate were selected from the initial ten candidate compounds. MD simulation indicated that these compounds are stable at 50-ns MD simulation when bound to RdRp protein. The screen hit compounds, remdesivir, molnupiravir, and GS-441524, are bound in the substrate binding pocket with good binding-free energy. As a consequence, capmatinib, pralsetinib, ponatinib, and tedizolid phosphate are potential new inhibitors of RdRp protein with potential of limiting COVID-19 infection by blocking RNA synthesis., Supplementary Information: The online version contains supplementary material available at 10.1007/s11224-022-02072-1., Competing Interests: Conflict of interestThe authors declare no competing interest., (© The Author(s) 2022.)
- Published
- 2023
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332. Plasmin Inhibitor in Health and Diabetes: Role of the Protein as a Therapeutic Target.
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Alsayejh B, Kietsiriroje N, Almutairi M, Simmons K, Pechlivani N, Ponnambalam S, and Ajjan RA
- Abstract
The vascular obstructive thrombus is composed of a mesh of fibrin fibers with blood cells trapped in these networks. Enhanced fibrin clot formation and/or suppression of fibrinolysis are associated with an increased risk of vascular occlusive events. Inhibitors of coagulation factors and activators of plasminogen have been clinically used to limit fibrin network formation and enhance lysis. While these agents are effective at reducing vascular occlusion, they carry a significant risk of bleeding complications. Fibrin clot lysis, essential for normal hemostasis, is controlled by several factors including the incorporation of antifibrinolytic proteins into the clot. Plasmin inhibitor (PI), a key antifibrinolytic protein, is cross-linked into fibrin networks with higher concentrations of PI documented in fibrin clots and plasma from high vascular risk individuals. This review is focused on exploring PI as a target for the prevention and treatment of vascular occlusive disease. We first discuss the relationship between the PI structure and antifibrinolytic activity, followed by describing the function of the protein in normal physiology and its role in pathological vascular thrombosis. Subsequently, we describe in detail the potential use of PI as a therapeutic target, including the array of methods employed for the modulation of protein activity. Effective and safe inhibition of PI may prove to be an alternative and specific way to reduce vascular thrombotic events while keeping bleeding risk to a minimum. Key Points Plasmin inhibitor (PI) is a key protein that inhibits fibrinolysis and stabilizes the fibrin network.This review is focused on discussing mechanistic pathways for PI action, role of the molecule in disease states, and potential use as a therapeutic target., Competing Interests: Conflicts of Interest None declared., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. ( https://creativecommons.org/licenses/by-nc-nd/4.0/ ).)
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- 2022
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333. Effectiveness of a school-based nutrition education program on waist circumference and dietary behavior among overweight adolescents in Puducherry, India.
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Ponnambalam S, Palanisamy S, Singaravelu R, and Arambakkam Janardhanan H
- Abstract
Background: The influence of western lifestyle such as high-caloric dense food and sedentary lifestyle has a great influence on Indian children, and the current prevalence of childhood overweight in India ranges between 4% and 22%. The primary aim of the study was to determine the change in growth parameters (waist circumference) as well as dietary behaviors at baseline and at the end of first, third, sixth, and ninth months among overweight adolescent girls and boys following a school-based nutritional education program., Materials and Methods: The study was conducted in 2019 in four urban schools at Puducherry which were randomly assigned to study and control groups by lottery method, and 140 overweight children aged 11-14 years were in the study group and 140 children were in the control group. Simple random sampling method was used to select the samples A nutrition education program highlighting the importance of balanced nutrition and the ill effects of obesity was imparted to students in the study group through a PowerPoint presentation. As a means of reinforcement, posters and pamphlets were distributed. The waist circumference and the mean calorie, protein, and fat intake were assessed at baseline and at the first, third, sixth, and ninth months and compared between groups using independent t test., Results: There was a statistically significant reduction in waist circumference in the study group when compared to the control group at P < 0.05. A significant decrease in the calorie intake at P < 0.001 and fat intake at P < 0.01 was observed in the study group. The protein intake in the study group increased at the end of 9 months, which was significant at P < 0.001., Conclusion: School-based nutritional education program has been found to be a successful intervention in controlling unnecessary weight gain among overweight adolescents., Competing Interests: There are no conflicts of interest., (Copyright: © 2022 Journal of Education and Health Promotion.)
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- 2022
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334. TDO2 modulates liver cancer cell migration and invasion via the Wnt5a pathway.
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Liu H, Xiang Y, Zong QB, Dai ZT, Wu H, Zhang HM, Huang Y, Shen C, Wang J, Lu ZX, Ponnambalam S, Chen K, Wu Y, Zhang TC, and Liao XH
- Subjects
- Animals, Biomarkers, Tumor, Cell Line, Cell Movement, Humans, Mice, Tryptophan metabolism, Wnt-5a Protein genetics, Liver Neoplasms drug therapy, Liver Neoplasms genetics, Tryptophan Oxygenase genetics, Tryptophan Oxygenase metabolism
- Abstract
Liver cancer is a malignant cancer phenotype for which there currently remains a lack of reliable biomarkers and therapeutic targets for disease management. Tryptophan 2,3‑dioxygenase (TDO2), a heme‑containing polyoxygenase enzyme, is primarily expressed in cells of the liver and nervous systems. In the present study, through the combination of cancer bioinformatics and analysis of clinical patient samples, it was shown that TDO2 expression in liver cancer tissue samples was significantly higher than that in normal tissues, and liver cancer patients with high TDO2 expression had a poor prognosis. Mechanistic studies on liver cancer cells showed that TDO2 promoted cancer cell migration and invasion via signal transduction through the Wnt5a pathway. Such regulation impacted the expression of cancer‑associated biomarkers, such as matrix metalloprotease 7 (MMP7) and the cell adhesion receptor CD44. Treatment with a calcium channel blocker (azelnidipine) reduced TDO2 levels and inhibited liver cancer cell migration and invasion. A mouse xenograft cancer model showed that TDO2 promoted tumorigenesis. Furthermore, azelnidipine treatment to downregulate TDO2 also decreased liver cancer development in this mouse cancer model. TDO2 is thus not only a useful liver cancer biomarker but a potential drug target for management of liver cancer.
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- 2022
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335. Affinity purification of fibrinogen using an Affimer column.
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Pechlivani N, Kearney KJ, Tiede C, Cheah R, Phoenix F, Ponnambalam S, Ault JR, McPherson MJ, Tomlinson DC, and Ajjan RA
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- Chromatography, Affinity methods, Hemostasis, Humans, Plasminogen, Fibrin metabolism, Fibrinogen metabolism
- Abstract
Background: Fibrinogen is an abundant plasma protein with an essential role in blood coagulation and haemostasis thus receiving significant research interest. However, protein purification is time consuming and commercial preparations often have protein contaminants. The aim of this study was to develop a new method to purify high quality and functional fibrinogen., Methods: Fibrinogen-specific Affimer protein, isolated using phage display systems, was immobilised to SulfoLink resin column and employed for fibrinogen purification from plasma samples. Fibrinogen was eluted using a high pH solution. Commercial human fibrinogen was also further purified using the Affimer column. Fibrinogen purity was determined by SDS-PAGE and mass spectrometry, while functionality was assessed using turbidimetric analysis., Results: Affimer-purified fibrinogen from human plasma showed purity at least comparable to commercially available preparations and was able to form physiological fibrin networks. Further purification of commercially available fibrinogen using the Affimercolumn eliminated multiple contaminant proteins, a significant number of which are key elements of the coagulation cascade, including plasminogen and factor XIII., Conclusions: The Affimercolumn represents a proof of concept novel, rapid method for isolating functional fibrinogen from plasma and for further purification of commercially available fibrinogen preparations., General Significance: Our methodology provides an efficient way of purifying functional fibrinogen with superior purity without the need of expensive pieces of equipment or the use of harsh conditions., (Copyright © 2022 Elsevier B.V. All rights reserved.)
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- 2022
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336. Effectiveness of After-School Physical Activity Intervention on Body Mass Index and Waist Circumference/Height Ratio among Overweight Adolescents in Selected Schools at Puducherry, India: A Randomized Controlled Trial.
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Ponnambalam S, Palanisamy S, Singaravelu R, and Janardhanan HA
- Abstract
Background: Globally, the prevalence of overweight and obesity has dramatically increased in the recent years. In India, more than 10% of schoolchildren are overweight or obese. Schools play a major role in the modification of behavior. The aim of this study was to assess the effectiveness of after-school physical activity intervention on body mass index (BMI) and waist circumference/height ratio as primary outcomes., Materials and Methods: A randomized controlled trial was adopted where the schools were randomized. Each group, i.e., study and control groups, had 140 overweight adolescents. BMI and waist circumference/height ratio were measured. After-school physical activity intervention was carried out for a period of 9 months by the study group. The posttests were carried out at an interval of 3 months up till 9 months., Results: There was a statistically significant difference in BMI between the study and control groups during the 6
th and 9th months (t = 1.256, P < 0.001 and t = 0.920, P < 0.001), respectively. The repeated measures analysis of variance did not show a significant reduction in BMI and waist circumference/height ratio over a period of time., Conclusion: School-based physical activity interventions are effective in prevention of childhood overweight/obesity and are a very cost-effective measure that can be easily implemented in schools., Competing Interests: There are no conflicts of interest., (Copyright: © 2022 Indian Journal of Community Medicine.)- Published
- 2022
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337. Purification and Analysis of Circulating Lipid Particles.
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Roper BWR, Al-Sayejh B, Al-Aufi A, Cuthbert GA, Lacey K, Homer-Vanniasinkam S, Harrison MA, Tomlinson DC, Ajjan R, and Ponnambalam S
- Subjects
- Humans, Lipid Metabolism, Ultracentrifugation, Atherosclerosis, Lipoproteins, LDL chemistry
- Abstract
Lipid particles found in circulating extracellular fluids such as blood or lymph are essential for cellular homeostasis, metabolism and survival. Such particles provide essential lipids and fats which enable cells to synthesize new membranes and regulate different biochemical pathways. Imbalance in lipid particle metabolism can cause pathological states such as atherosclerosis. Here, elevated low-density lipoprotein (LDL) accumulation leads to fat-filled lesions or plaques in arterial walls. In this chapter, we provide a detailed set of protocols for the rapid and safe purification of lipid particles from human blood using high-speed ultracentrifugation. We provide a detailed set of assays for further analysis of the biochemical and cellular properties of these lipid particles. By combining these assays, we can better understand the complex roles of different lipid particles in normal physiology and disease pathology., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)
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- 2022
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338. Monitoring VEGF-Stimulated Calcium Ion Flux in Endothelial Cells.
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Critchley WR, Fearnley GWF, Abdul-Zani I, Molina-Paris C, Bendtsen C, Zachary IC, Harrison MA, and Ponnambalam S
- Subjects
- Animals, Calcium metabolism, Cell Movement, Cells, Cultured, Neovascularization, Physiologic physiology, Phosphorylation, Signal Transduction physiology, Vascular Endothelial Growth Factor Receptor-2 metabolism, Endothelial Cells metabolism, Vascular Endothelial Growth Factor A metabolism, Vascular Endothelial Growth Factor A pharmacology
- Abstract
The endothelial response to vascular endothelial growth factor A (VEGF-A) regulates many aspects of animal physiology in health and disease. Such VEGF-A-regulated phenomena include vasculogenesis, angiogenesis, tumor growth and progression. VEGF-A binding to receptor tyrosine kinases such as vascular endothelial growth factor receptor 2 (VEGFR2 ) activates multiple signal transduction pathways and changes in homeostasis, metabolism, gene expression, cell proliferation, migration, and survival. One such VEGF-A-regulated response is a rapid rise in cytosolic calcium ion levels which modulates different biochemical events and impacts on endothelial-specific responses. Here, we present a series of detailed and robust protocols for evaluating ligand-stimulated cytosolic calcium ion flux in endothelial cells. By monitoring an endogenous endothelial transcription factor (NFATc2 ) which displays calcium-sensitive redistribution, we can assess the relevance of cytosolic calcium to protein function. This protocol can be easily applied to both adherent and non-adherent cultured cells to evaluate calcium ion flux in response to exogenous stimuli such as VEGF-A., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)
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- 2022
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339. Regulation of follistatin-like 3 expression by miR-486-5p modulates gastric cancer cell proliferation, migration and tumor progression.
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Dai ZT, Xiang Y, Zhang XY, Zong QB, Wu QF, Huang Y, Shen C, Li JP, Ponnambalam S, and Liao XH
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- Animals, Apoptosis, Cell Line, Tumor, Cell Movement, Cell Proliferation, Follistatin-Related Proteins genetics, Humans, Mice, Mice, Inbred BALB C, MicroRNAs genetics, Neoplasm Staging, Stomach Neoplasms genetics, Stomach Neoplasms pathology, Follistatin-Related Proteins metabolism, MicroRNAs metabolism, Stomach Neoplasms metabolism, Stomach Neoplasms physiopathology
- Abstract
Cancer development and progression can be regulated by the levels of endogenous factors. Gastric cancer is an aggressive disease state with poor patient prognosis, needing the development of new diagnostics and therapeutic strategies. We investigated the close association between follistatin-like 3 (FSTL3) and different cancers, and focused on its role in gastric cancer cell function. Using cancer bioinformatics, we found that FSTL3 expression is elevated in a large majority of the 33 cancers we analyzed in publicly available cancer databases. Elevated levels of FSTL3 is associated with poor patient prognosis in gastric cancer. In a comparison of normal gastric epithelial cells and gastric cancer cell lines, FSTL3 expression was consistently elevated in gastric cancer cells. Overexpression of FSTL3 promoted gastric cancer cell viability, proliferation and migration. Conversely, FSTL3 knockdown inhibits these cellular processes. Using bioinformatics, we found that the FSTL3 mRNA has a potential binding site in the 3'-UTR for a small microRNA, miR-486-5p. Further bioinformatics revealed significant negative correlation between FSTL3 and miR-486-5p levels. Using luciferase reporter constructs, we provide evidence that the 3'UTR from the FSTL3 mRNA can confer downregulation in the presence of miR-486-5p. These studies lead us to conclude that FSTL3 has oncogenic properties and increased expression of this gene product promotes gastric cancer development and progression.
- Published
- 2021
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340. Fibrinogen interaction with complement C3: a potential therapeutic target to reduce thrombosis risk.
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King RJ, Schuett K, Tiede C, Jankowski V, John V, Trehan A, Simmons K, Ponnambalam S, Storey RF, Fishwick CWG, McPherson MJ, Tomlinson DC, and Ajjan RA
- Subjects
- Complement C3, Fibrin, Fibrinolysis, Humans, Fibrinogen, Thrombosis drug therapy, Thrombosis etiology, Thrombosis prevention & control
- Abstract
Complement C3 binds fibrinogen and compromises fibrin clot lysis thereby enhancing thrombosis risk. We investigated the role of fibrinogen-C3 interaction as a novel therapeutic target to reduce thrombosis risk by analysing: i) consistency in the fibrinolytic properties of C3, ii) binding sites between fibrinogen and C3 and iii) modulation of fibrin clot lysis by manipulating fibrinogen-C3 interactions. Purified fibrinogen and C3 from the same individuals (n=24) were used to assess inter-individual variability in the anti-fibrinolytic effects of C3. Microarray screening and molecular modelling evaluated C3 and fibrinogen interaction sites. Novel synthetic conformational proteins, termed Affimers, were used to modulate C3-fibrinogen interaction and fibrinolysis. C3 purified from patients with type 1 diabetes showed enhanced prolongation of fibrinolysis compared with healthy control protein [195±105 and 522±166 seconds, respectively (p=0.04)], with consistent effects but a wider range (5-51% and 5-18% lysis prolongation, respectively). Peptide microarray screening identified 2 potential C3-fibrinogen interactions sites within fibrinogen β chain (residues 424-433, 435-445). One fibrinogen-binding Affimer was isolated that displayed sequence identity with C3 in an exposed area of the protein. This Affimer abolished C3-induced prolongation of fibrinolysis (728±25.1 seconds to 632±23.7 seconds, p=0.005) and showed binding to fibrinogen in the same region that is involved in C3-fibrinogen interactions. Moreover, it shortened plasma clot lysis of patients with diabetes, cardiovascular disease or controls by 7-11%. C3 binds fibrinogen β-chain and disruption of fibrinogen-C3 interaction using Affimer proteins enhances fibrinolysis, which represents a potential novel target tool to reduce thrombosis in high risk individuals.
- Published
- 2021
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341. Prognostic value of members of NFAT family for pan-cancer and a prediction model based on NFAT2 in bladder cancer.
- Author
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Dai ZT, Xiang Y, Wang Y, Bao LY, Wang J, Li JP, Zhang HM, Lu Z, Ponnambalam S, and Liao XH
- Subjects
- Cell Line, Tumor, Gene Expression Profiling, Gene Expression Regulation, Neoplastic, Gene Ontology, Humans, Kaplan-Meier Estimate, NFATC Transcription Factors genetics, Oncogenes, Prognosis, Proportional Hazards Models, Protein Interaction Maps genetics, Reproducibility of Results, Risk Factors, Urinary Bladder Neoplasms genetics, Urinary Bladder Neoplasms pathology, Models, Biological, NFATC Transcription Factors metabolism, Urinary Bladder Neoplasms diagnosis, Urinary Bladder Neoplasms metabolism
- Abstract
Bladder cancer (BLCA) is one of the common malignant tumors of the urinary system. The poor prognosis of BLCA patients is due to the lack of early diagnosis and disease recurrence after treatment. Increasing evidence suggests that gene products of the nuclear factor of activated T-cells (NFAT) family are involved in BLCA progression and subsequent interaction(s) with immune surveillance. In this study, we carried out a pan-cancer analysis of the NFAT family and found that NFAT2 is an independent prognostic factor for BLCA. We then screened for differentially expressed genes (DEGs) and further analyzed such candidate gene loci using gene ontology enrichment to curate the KEGG database. We then used Lasso and multivariate Cox regression to identify 4 gene loci (FER1L4, RNF128, EPHB6, and FN1) which were screened together with NFAT2 to construct a prognostic model based on using Kaplan-Meier analysis to predict the overall survival of BLCA patients. Moreover, the accuracy of our proposed model is supported by deposited datasets in the Gene Expression Omnibus (GEO) database. Finally, a nomogram of this prognosis model for BLCA was established which could help to provide better disease management and treatment.
- Published
- 2021
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342. Structural Basis for Vascular Endothelial Growth Factor Receptor Activation and Implications for Disease Therapy.
- Author
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Shaik F, Cuthbert GA, Homer-Vanniasinkam S, Muench SP, Ponnambalam S, and Harrison MA
- Subjects
- Animals, Humans, Ligands, Protein Domains, Protein Kinase Inhibitors chemistry, Protein Kinase Inhibitors pharmacology, Receptors, Vascular Endothelial Growth Factor antagonists & inhibitors, Signal Transduction, Vascular Endothelial Growth Factor A metabolism, Disease, Receptors, Vascular Endothelial Growth Factor chemistry, Receptors, Vascular Endothelial Growth Factor metabolism
- Abstract
Vascular endothelial growth factors (VEGFs) bind to membrane receptors on a wide variety of cells to regulate diverse biological responses. The VEGF-A family member promotes vasculogenesis and angiogenesis, processes which are essential for vascular development and physiology. As angiogenesis can be subverted in many disease states, including tumour development and progression, there is much interest in understanding the mechanistic basis for how VEGF-A regulates cell and tissue function. VEGF-A binds with high affinity to two VEGF receptor tyrosine kinases (VEGFR1, VEGFR2) and with lower affinity to co-receptors called neuropilin-1 and neuropilin-2 (NRP1, NRP2). Here, we use a structural viewpoint to summarise our current knowledge of VEGF-VEGFR activation and signal transduction. As targeting VEGF-VEGFR activation holds much therapeutic promise, we examine the structural basis for anti-angiogenic therapy using small-molecule compounds such as tyrosine kinase inhibitors that block VEGFR activation and downstream signalling. This review provides a rational basis towards reconciling VEGF and VEGFR structure and function in developing new therapeutics for a diverse range of ailments.
- Published
- 2020
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343. Scavenger Receptors as Biomarkers and Therapeutic Targets in Cardiovascular Disease.
- Author
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Cuthbert GA, Shaik F, Harrison MA, Ponnambalam S, and Homer-Vanniasinkam S
- Subjects
- Humans, Atherosclerosis therapy, Biomarkers metabolism, Cardiovascular Diseases therapy, Receptors, Scavenger metabolism
- Abstract
The process of atherosclerosis leads to the formation of plaques in the arterial wall, resulting in a decreased blood supply to tissues and organs and its sequelae: morbidity and mortality. A class of membrane-bound proteins termed scavenger receptors (SRs) are closely linked to the initiation and progression of atherosclerosis. Increasing interest in understanding SR structure and function has led to the idea that these proteins could provide new routes for cardiovascular disease diagnosis, management, and treatment. In this review, we consider the main classes of SRs that are implicated in arterial disease. We consider how our understanding of SR-mediated recognition of diverse ligands, including modified lipid particles, lipids, and carbohydrates, has enabled us to better target SR-linked functionality in disease. We also link clinical studies on vascular disease to our current understanding of SR biology and highlight potential areas that are relevant to cardiovascular disease management and therapy.
- Published
- 2020
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344. Chemical activation of the Piezo1 channel drives mesenchymal stem cell migration via inducing ATP release and activation of P2 receptor purinergic signaling.
- Author
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Mousawi F, Peng H, Li J, Ponnambalam S, Roger S, Zhao H, Yang X, and Jiang LH
- Subjects
- Adult, Cell Movement, Child, Female, Humans, Male, Signal Transduction, Young Adult, Adenosine Triphosphate metabolism, Ion Channels metabolism, Mesenchymal Stem Cells metabolism, Receptors, Purinergic P2 metabolism
- Abstract
In this study, we examined the Ca
2+ -permeable Piezo1 channel, a newly identified mechanosensing ion channel, in human dental pulp-derived mesenchymal stem cells (MSCs) and hypothesized that activation of the Piezo1 channel regulates MSC migration via inducing ATP release and activation of the P2 receptor purinergic signaling. The Piezo1 mRNA and protein were readily detected in hDP-MSCs from multiple donors and, consistently, brief exposure to Yoda1, the Piezo1 channel-specific activator, elevated intracellular Ca2+ concentration. Yoda1-induced Ca2+ response was inhibited by ruthenium red or GsMTx4, two Piezo1 channel inhibitors, and also by Piezo1-specific siRNA. Brief exposure to Yoda1 also induced ATP release. Persistent exposure to Yoda1 stimulated MSC migration, which was suppressed by Piezo1-specific siRNA, and also prevented by apyrase, an ATP scavenger, or PPADS, a P2 generic antagonist. Furthermore, stimulation of MSC migration induced by Yoda1 as well as ATP was suppressed by PF431396, a PYK2 kinase inhibitor, or U0126, an inhibitor of the mitogen-activated protein kinase MEK/ERK signaling pathway. Collectively, these results suggest that activation of the Piezo1 channel stimulates MSC migration via inducing ATP release and subsequent activation of the P2 receptor purinergic signaling and downstream PYK2 and MEK/ERK signaling pathways, thus revealing novel insights into the molecular and signaling mechanisms regulating MSC migration. Such findings provide useful information for evolving a full understanding of MSC migration and homing and developing strategies to improve MSC-based translational applications., (©2019 The Authors. Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press 2019.)- Published
- 2020
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345. ATF-2 and Tpl2 regulation of endothelial cell cycle progression and apoptosis.
- Author
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Fearnley GW, Latham AM, Hollstein M, Odell AF, and Ponnambalam S
- Subjects
- Cell Line, Cell Proliferation, Humans, Signal Transduction, Activating Transcription Factor 2 metabolism, Apoptosis, Cell Cycle, Human Umbilical Vein Endothelial Cells cytology, MAP Kinase Kinase Kinases metabolism, Proto-Oncogene Proteins metabolism, Vascular Endothelial Growth Factor A metabolism
- Abstract
Cells respond to soluble and membrane-bound factors to activate signalling cascades that control cell proliferation and cell death. Vascular endothelial growth factor A (VEGF-A) is a soluble ligand that modulates a variety of cellular responses including cell proliferation and apoptosis. It is not well understood how VEGF-A signalling pathways regulate cell proliferation and cell death. To address this, we examined VEGF-A-regulated signalling pathways in the cytosol and nucleus and functional requirement for such cellular responses. The VEGF-A-regulated transcription factor, ATF-2, is required for cell cycle proteins such as p53, p21 and Cyclin D1. A cytosolic serine/threonine protein kinase (Tpl2) modulates ATF-2-regulated effects on the endothelial cell cycle. Such regulatory effects impact on endothelial cell proliferation, cell viability and apoptosis. These cellular effects influence complex cell-based organisation such as endothelial tubulogenesis. Our study now provides a framework for incorporating VEGF-A-stimulated signalling events from the cytosol to the nucleus which helps to understand how cell proliferation and apoptosis are controlled., (Copyright © 2019 Elsevier Inc. All rights reserved.)
- Published
- 2020
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346. Postoperative Remote Automated Monitoring: Need for and State of the Science.
- Author
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McGillion MH, Duceppe E, Allan K, Marcucci M, Yang S, Johnson AP, Ross-Howe S, Peter E, Scott T, Ouellette C, Henry S, Le Manach Y, Paré G, Downey B, Carroll SL, Mills J, Turner A, Clyne W, Dvirnik N, Mierdel S, Poole L, Nelson M, Harvey V, Good A, Pettit S, Sanchez K, Harsha P, Mohajer D, Ponnambalam S, Bhavnani S, Lamy A, Whitlock R, and Devereaux PJ
- Subjects
- Humans, Monitoring, Physiologic methods, Postoperative Care methods, Surgical Procedures, Operative, Telemedicine methods, Vital Signs physiology
- Abstract
Worldwide, more than 230 million adults have major noncardiac surgery each year. Although surgery can improve quality and duration of life, it can also precipitate major complications. Moreover, a substantial proportion of deaths occur after discharge. Current systems for monitoring patients postoperatively, on surgical wards and after transition to home, are inadequate. On the surgical ward, vital signs evaluation usually occurs only every 4-8 hours. Reduced in-hospital ward monitoring, followed by no vital signs monitoring at home, leads to thousands of cases of undetected/delayed detection of hemodynamic compromise. In this article we review work to date on postoperative remote automated monitoring on surgical wards and strategy for advancing this field. Key considerations for overcoming current barriers to implementing remote automated monitoring in Canada are also presented., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2018
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347. Receptor Tyrosine Kinase Ubiquitination and De-Ubiquitination in Signal Transduction and Receptor Trafficking.
- Author
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Critchley WR, Pellet-Many C, Ringham-Terry B, Harrison MA, Zachary IC, and Ponnambalam S
- Abstract
Receptor tyrosine kinases (RTKs) are membrane-based sensors that enable rapid communication between cells and their environment. Evidence is now emerging that interdependent regulatory mechanisms, such as membrane trafficking, ubiquitination, proteolysis and gene expression, have substantial effects on RTK signal transduction and cellular responses. Different RTKs exhibit both basal and ligand-stimulated ubiquitination, linked to trafficking through different intracellular compartments including the secretory pathway, plasma membrane, endosomes and lysosomes. The ubiquitin ligase superfamily comprising the E1, E2 and E3 enzymes are increasingly implicated in this post-translational modification by adding mono- and polyubiquitin tags to RTKs. Conversely, removal of these ubiquitin tags by proteases called de-ubiquitinases (DUBs) enables RTK recycling for another round of ligand sensing and signal transduction. The endocytosis of basal and activated RTKs from the plasma membrane is closely linked to controlled proteolysis after trafficking and delivery to late endosomes and lysosomes. Proteolytic RTK fragments can also have the capacity to move to compartments such as the nucleus and regulate gene expression. Such mechanistic diversity now provides new opportunities for modulating RTK-regulated cellular responses in health and disease states., Competing Interests: The authors declare no conflict of interest.
- Published
- 2018
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348. IL-36γ Is a Strong Inducer of IL-23 in Psoriatic Cells and Activates Angiogenesis.
- Author
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Bridgewood C, Fearnley GW, Berekmeri A, Laws P, Macleod T, Ponnambalam S, Stacey M, Graham A, and Wittmann M
- Subjects
- Humans, Inflammation, Interleukin-17 immunology, Keratinocytes, Macrophages drug effects, Macrophages immunology, Macrophages pathology, Neovascularization, Pathologic, Psoriasis pathology, Skin pathology, Tumor Necrosis Factor-alpha immunology, Angiogenesis Inducing Agents, Endothelial Cells immunology, Interleukin-1 pharmacology, Interleukin-23 immunology, Psoriasis immunology, Skin immunology
- Abstract
The IL-1 family member cytokine IL-36γ is recognised as key mediator in the immunopathology of psoriasis, hallmarks of which involve the activation of both resident and infiltrating inflammatory myeloid cells and aberrant angiogenesis. This research demonstrates a role for IL-36γ in both myeloid activation and angiogenesis. We show that IL-36γ induces the production of psoriasis-associated cytokines from macrophages (IL-23 and TNFα) and that this response is enhanced in macrophages from psoriasis patients. This effect is specific for IL-36γ and could not be mimicked by other IL-1 family cytokines such as IL-1α. IL-36γ was also demonstrated to induce endothelial tube formation and branching, in a VEGF-A-dependent manner. Furthermore, IL-36γ-stimulated macrophages potently activated endothelial cells and led to increased adherence of monocytes, effects that were markedly more pronounced for psoriatic macrophages. Interestingly, regardless of stimulus, psoriasis monocytes showed increased adherence to both the stimulated and unstimulated endothelium when compared with monocytes from healthy individuals. Collectively, these findings show that IL-36γ has the potential to enhance endothelium directed leucocyte infiltration into the skin and strengthen the IL-23/IL-17 pathway adding to the growing evidence of pathogenetic roles for IL-36γ in psoriatic responses. Our findings also point to a cellular response, which could potentially explain cardiovascular comorbidities in psoriasis in the form of endothelial activation and increased monocyte adherence.
- Published
- 2018
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349. Ubiquitination of basal VEGFR2 regulates signal transduction and endothelial function.
- Author
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Smith GA, Fearnley GW, Abdul-Zani I, Wheatcroft SB, Tomlinson DC, Harrison MA, and Ponnambalam S
- Abstract
Cell surface receptors can undergo recycling or proteolysis but the cellular decision-making events that sort between these pathways remain poorly defined. Vascular endothelial growth factor A (VEGF-A) and vascular endothelial growth factor receptor 2 (VEGFR2) regulate signal transduction and angiogenesis, but how signaling and proteolysis is regulated is not well understood. Here, we provide evidence that a pathway requiring the E1 ubiquitin-activating enzyme UBA1 controls basal VEGFR2 levels, hence metering plasma membrane receptor availability for the VEGF-A-regulated endothelial cell response. VEGFR2 undergoes VEGF-A-independent constitutive degradation via a UBA1-dependent ubiquitin-linked pathway. Depletion of UBA1 increased VEGFR2 recycling from endosome-to-plasma membrane and decreased proteolysis. Increased membrane receptor availability after UBA1 depletion elevated VEGF-A-stimulated activation of key signaling enzymes such as PLCγ1 and ERK1/2. Although UBA1 depletion caused an overall decrease in endothelial cell proliferation, surviving cells showed greater VEGF-A-stimulated responses such as cell migration and tubulogenesis. Our study now suggests that a ubiquitin-linked pathway regulates the balance between receptor recycling and degradation which in turn impacts on the intensity and duration of VEGF-A-stimulated signal transduction and the endothelial response., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2017. Published by The Company of Biologists Ltd.)
- Published
- 2017
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350. Affimer proteins are versatile and renewable affinity reagents.
- Author
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Tiede C, Bedford R, Heseltine SJ, Smith G, Wijetunga I, Ross R, AlQallaf D, Roberts AP, Balls A, Curd A, Hughes RE, Martin H, Needham SR, Zanetti-Domingues LC, Sadigh Y, Peacock TP, Tang AA, Gibson N, Kyle H, Platt GW, Ingram N, Taylor T, Coletta LP, Manfield I, Knowles M, Bell S, Esteves F, Maqbool A, Prasad RK, Drinkhill M, Bon RS, Patel V, Goodchild SA, Martin-Fernandez M, Owens RJ, Nettleship JE, Webb ME, Harrison M, Lippiat JD, Ponnambalam S, Peckham M, Smith A, Ferrigno PK, Johnson M, McPherson MJ, and Tomlinson DC
- Subjects
- Animals, Mice, Carrier Proteins analysis, Carrier Proteins metabolism, Molecular Biology methods, Staining and Labeling methods
- Abstract
Molecular recognition reagents are key tools for understanding biological processes and are used universally by scientists to study protein expression, localisation and interactions. Antibodies remain the most widely used of such reagents and many show excellent performance, although some are poorly characterised or have stability or batch variability issues, supporting the use of alternative binding proteins as complementary reagents for many applications. Here we report on the use of Affimer proteins as research reagents. We selected 12 diverse molecular targets for Affimer selection to exemplify their use in common molecular and cellular applications including the (a) selection against various target molecules; (b) modulation of protein function in vitro and in vivo; (c) labelling of tumour antigens in mouse models; and (d) use in affinity fluorescence and super-resolution microscopy. This work shows that Affimer proteins, as is the case for other alternative binding scaffolds, represent complementary affinity reagents to antibodies for various molecular and cell biology applications.
- Published
- 2017
- Full Text
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