Imperial College London

Professor Xiao Yun Xu

Faculty of EngineeringDepartment of Chemical Engineering

Professor, Biofluid Mechanics & Director of Graduate School
 
 
 
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Contact

 

yun.xu Website

 
 
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Location

 

407ACE ExtensionSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

242 results found

Zhan W, Gedroyc W, Xu XY, 2014, Mathematical Modelling of Drug Transport and Uptake in a Realistic Model of Solid Tumour., Protein and Peptide Letters, Vol: 21, Pages: 1146-1156, ISSN: 1875-5305

Effective delivery of therapeutic agents to tumour cells is essential to the success of most cancer treatment therapies except for surgery. The transport of drug in solid tumours involves multiple biophysical and biochemical processes which are strongly dependent on the physicochemical properties of the drug and biological properties of the tumour. Owing to the complexities involved, mathematical models are playing an increasingly important role in identifying the factors leading to inadequate drug delivery to tumours. In this study, a computational model is developed which incorporates real tumour geometry reconstructed from magnetic resonance images, drug transport through the tumour vasculature and interstitium, as well as drug uptake by tumour cells. The effectiveness of anticancer therapy is evaluated based on the percentage of survival tumour cells by directly solving the pharmacodynamics equation using predicted intracellular drug concentrations. Computational simulations are performed for the delivery of doxorubicin through different administration modes and doses. Our predictions show that continuous infusion is far more effective than bolus injection in maintaining high levels of intracellular drug concentration, thereby increasing drug uptake by tumour cells. On the other hand, bolus injection leads to higher extracellular concentration in both tumour and normal tissues compared to continuous infusion, which is undesirable as high drug concentration in normal tissues may increase the risk of associated side effects.

Journal article

Massai D, Pisani G, Rodriguez A, Logrand F, Isu G, Labate GFD, Xu XY, Bignardi C, Tarone G, Morbiducci Uet al., 2014, A bioreactor-based model system for cardiac tissue investigation and culture, JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Vol: 8, Pages: 481-481, ISSN: 1932-6254

Journal article

Kousera CA, Nijjer S, Torii R, Petraco R, Sen S, Foin N, Hughes AD, Francis DPP, Xu XY, Davies JEet al., 2014, Patient-Specific Coronary Stenoses Can Be Modeled Using a Combination of OCT and Flow Velocities to Accurately Predict Hyperemic Pressure Gradients, IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, Vol: 61, Pages: 1902-1913, ISSN: 0018-9294

Journal article

Su J, Gu Z, Zhang M, Xu XYet al., 2014, An improved version of RIGID for discrete element simulation of particle flows with arbitrarily complex geometries, POWDER TECHNOLOGY, Vol: 253, Pages: 393-405, ISSN: 0032-5910

Journal article

Zhan W, Xu XY, 2014, Simulation of hifu heating in solid tumour: Comparison of different temperature control modes, Pages: 176-179, ISSN: 2305-5995

© 2014, Dalian University of Technology. All rights reserved. Three different temperature control modes used in high intensity focused ultrasound (HIFU) heating of solid tumour are compared in this study. Results show that the control mode with an independent temperature monitor for each focused region is effective in achieving a rapid temperature rise and maintaining a stable temperature level in tumour.

Conference paper

Gu B, Adjiman C, Xu Y, 2014, An integrated model of a spiral-wound membrane module for reverse osmosis considering the effects of winding and spacers, Pages: 566-568

Conference paper

Liu C, Krishnan J, Xu X-Y, 2013, Towards an integrated systems-based modelling framework for drug transport and its effect on tumour cells, Journal of Biological Engineering

Journal article

Kousera CA, Nijjer SS, Torii R, Petraco R, Sen S, Foin N, Broyd C, Hughes AD, Xu YX, Francis DP, Davies JEet al., 2013, Patient-specific Coronary Stenoses Can Be Modeled Using a Combination of Optical Coherence Tomography and Flow Velocities to Accurately Predict Hyperaemic Pressure Gradients, 25th Annual Symposium on Transcatheter Cardiovascular Therapeutics (TCT), Publisher: ELSEVIER SCIENCE INC, Pages: B186-B186, ISSN: 0735-1097

Conference paper

Kousera CA, Nijjer SS, Torii R, Petraco R, Sen S, Foin N, Broyd C, Hughes AD, Xu YX, Francis DP, Davies JEet al., 2013, Optical Coherence Tomography can be combined with angiography to create highly accurate patient-specific models of human coronary anatomy in a rapid automated manner, 25th Annual Symposium on Transcatheter Cardiovascular Therapeutics (TCT), Publisher: ELSEVIER SCIENCE INC, Pages: B195-B195, ISSN: 0735-1097

Conference paper

Lattimer CR, Azzam M, Kalodiki E, Xu X, Geroulakos G, Lattimer CR, Azzam M, Kalodiki E, Xu XY, Geroulakos G, Lattimer CR, Azzam M, Kalodiki E, Geroulakos Get al., 2013, Hemodynamic changes in the femoral vein with increasing outflow resistance, Journal of Vascular Surgery, Vol: 2, Pages: 26-33, ISSN: 1097-6809

Journal article

Zhang X, Luckham PF, Hughes AD, Thom S, Xu XYet al., 2013, Towards an understanding of the release behavior of temperature-sensitive liposomes: a possible explanation of the "pseudoequilibrium'' release behavior at the phase transition temperature, JOURNAL OF LIPOSOME RESEARCH, Vol: 23, Pages: 167-173, ISSN: 0898-2104

Journal article

Torii R, Kalantzi M, Theodoropoulos S, Sarathchandra P, Xu XY, Yacoub MHet al., 2013, Predicting Impending Rupture of the Ascending Aorta With Bicuspid Aortic Valve Spatiotemporal Flow and Wall Shear Stress, JACC-CARDIOVASCULAR IMAGING, Vol: 6, Pages: 1017-1019, ISSN: 1936-878X

Journal article

Moraldo M, Bergamini C, Malaweera ASN, Dhutia NM, Pabari PA, Willson K, Baruah R, Manisty C, Davies JE, Xu XY, Hughes AD, Francis DPet al., 2013, A novel fully automated method for mitral regurgitant orifice area quantification, International Journal of Cardiology, Vol: 166, Pages: 688-695, ISSN: 1874-1754

Background: Effective regurgitant orifice area (EROA) in mitral regurgitation (MR) is difficult to quantify.Clinically it is measured using the proximal isovelocity surface area (PISA) method, which is intrinsicallynot automatable, because it requires the operator to manually identify the mitral valve orifice. We introducea new fully automated algorithm, (“AQURO”), which calculates EROA directly from echocardiographic colourM-mode data, without requiring operator input.Methods: Multiple PISA measurements were compared to multiple AQURO measurements in twenty patientswith MR. For PISA analysis, three mutually blinded observers measured EROA from the four stored videoloops. For AQURO analysis, the software automatically processed the colour M-mode datasets and analysedthe velocity field in the flow-convergence zone to extract EROA directly without any requirement for manualradius measurement.Results: Reproducibility, measured by intraclass correlation (ICC), for PISA was 0.80, 0.83 and 0.83 (for 3 observersrespectively). Reproducibility for AQURO was 0.97. Agreement between replicate measurements calculatedusing Bland-Altman standard deviation of difference (SDD) was 21,17 and 17mm2for the threerespective observers viewing independent video loops using PISA. Agreement between replicate measurementsfor AQURO was 6, 5 and 7mm2for automated analysis of the three pairs of datasets.Conclusions: By eliminating the need to identify the orifice location, AQURO avoids an important source ofmeasurement variability. Compared with PISA, it also reduces the analysis time allowing analysis and averagingof data from significantly more beats, improving the consistency of EROA quantification.AQURO, being fully automated, is a simple, effective enhancement for EROA quantification using standardechocardiographic equipment.

Journal article

Zhan W, Gedroyc W, Xu X, 2013, Computational Study of Drug Transport in Realistic Models of Solid Tumour, Mathways into Cancer II

Conference paper

Wang Y, Downie S, Wood N, Firmin D, Xu XYet al., 2013, Finite element analysis of the deformation of deep veins in the lower limb under external compression, MEDICAL ENGINEERING & PHYSICS, Vol: 35, Pages: 515-523, ISSN: 1350-4533

Journal article

Cheng Z, Riga C, Chan J, Hamady M, Wood NB, Cheshire NJW, Xu Y, Gibbs RGJet al., 2013, Initial findings and potential applicability of computational simulation of the aorta in acute type B dissection, JOURNAL OF VASCULAR SURGERY, Vol: 57, Pages: 35S-43S, ISSN: 0741-5214

Journal article

Kousera CA, Wood NB, Seed WA, Torii R, O'Regan D, Xu XYet al., 2013, A Numerical Study of Aortic Flow Stability and Comparison With In Vivo Flow Measurements, JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME, Vol: 135, ISSN: 0148-0731

Journal article

Liu C, Krishnan J, Xu X-Y, 2013, Investigating the effects of ABC-transporter mediated acquired drug resistance mechanisms at the cell and tissue scale, Integrative Biology

Journal article

Zhan W, Xu XY, 2013, A mathematical model for thermosensitive liposomal delivery of Doxorubicin to solid tumour., J Drug Deliv, Vol: 2013, ISSN: 2090-3014

The effectiveness of anticancer treatments is often hampered by the serious side effects owing to toxicity of anticancer drugs and their undesirable uptake by healthy cells in vivo. Thermosensitive liposome-mediated drug delivery has been developed as part of research efforts aimed at improving therapeutic efficacy while reducing the associated side effect. Since multiple steps are involved in the transport of drug-loaded liposomes, drug release, and its uptake, mathematical models become an indispensible tool to analyse the transport processes and predict the outcome of anticancer treatment. In this study, a computational model is developed which incorporates the key physical and biochemical processes involved in drug delivery and cellular uptake. The model has been applied to idealized tumour geometry, and comparisons are made between continuous infusion of doxorubicin and thermosensitive liposome-mediated delivery. Results show that thermosensitive liposome-mediated delivery performs better in reducing drug concentration in normal tissues, which may help lower the risk of associated side effects. Compared with direct infusion over a 2-hour period, thermosensitive liposome delivery leads to a much higher peak intracellular concentration of doxorubicin, which may increase cell killing in tumour thereby enhancing the therapeutic effect of the drug.

Journal article

Moraldo M, Cecaro F, Shun-Shin M, Pabari P, Davies JE, Xu XY, Hughes AD, Manisty C, Francis DPet al., 2012, Evidence-based recommendations for PISA measurements in mitral regurgitation: systematic review, clinical and in-vitro study, Iinternational Journal of Cardiology

BackgroundGuidelines for quantifying mitral regurgitation (MR) using “proximal isovelocity surface area” (PISA) instruct operators to measure the PISA radius from valve orifice to Doppler flow convergence “hemisphere”. Using clinical data and a physically-constructed MR model we (A) analyse the actually-observed colour Doppler PISA shape and (B) test whether instructions to measure a “hemisphere” are helpful.Methods and resultsIn part A, the true shape of PISA shells was investigated using three separate approaches. First, a systematic review of published examples consistently showed non-hemispherical, “urchinoid” shapes. Second, our clinical data confirmed that the Doppler-visualized surface is non-hemispherical. Third, in-vitro experiments showed that round orifices never produce a colour Doppler hemisphere.In part B, six observers were instructed to measure hemisphere radius rh and (on a second viewing) urchinoid distance (du) in 11 clinical PISA datasets; 6 established experts also measured PISA distance as the gold standard. rh measurements, generated using the hemisphere instruction significantly underestimated expert values (−28%, p<0.0005), meaning rh2 was underestimated by approximately 2-fold. du measurements, generated using the non-hemisphere instruction were less biased (+7%, p=0.03).Finally, frame-to-frame variability in PISA distance was found to have a coefficient of variation (CV) of 25% in patients and 9% in in-vitro data. Beat-to-beat variability had a CV of 15% in patients.ConclusionsDoppler-visualized PISA shells are not hemispherical: we should avoid advising observers to measure a hemispherical radius because it encourages underestimation of orifice area by approximately two-fold. If precision is needed (e.g. to detect changes reliably) multi-frame averaging is essential.

Journal article

Zhan W, Gedroyc W, Xu X, 2012, Computational Study of Drug Transport in Realistic Models of Solid Tumour, AIChE Annual Conference

Conference paper

Foin N, Sen S, Petraco R, Torii R, Nijjer S, Xu YX, Mehta V, Mayet J, Hughes A, Francis D, Di Mario C, Krams R, Davies Jet al., 2012, Investigation of Fractional Flow Reserve Correlation with Direct Anatomical Parameters Using a Percutaneous Model of Coronary Artery Stenosis, Transcatheter Cardiovascular Therapeutics (TCT) Symposium, Publisher: ELSEVIER SCIENCE INC, Pages: B67-B67, ISSN: 0735-1097

Conference paper

Liu X, Fan Y, Xu XY, Deng Xet al., 2012, Nitric oxide transport in an axisymmetric stenosis, JOURNAL OF THE ROYAL SOCIETY INTERFACE, Vol: 9, Pages: 2468-2478, ISSN: 1742-5689

Journal article

Paopo I, Xu XY, Mantalaris A, 2012, Differentiation of murine embryonic stem cells (mESCs) into type II pneumocytes in a 3D sparged bioreactor, JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Vol: 6, Pages: 343-343, ISSN: 1932-6254

Journal article

Massai D, Soloperto G, Gallo D, Xu XY, Morbiducci Uet al., 2012, Shear-induced platelet activation and its relationship with blood flow topology in a numerical model of stenosed carotid bifurcation, EUROPEAN JOURNAL OF MECHANICS B-FLUIDS, Vol: 35, Pages: 92-101, ISSN: 0997-7546

Journal article

Torii R, El-Hamamsy I, Donya M, Babu-Narayan SV, Ibrahim M, Kilner PJ, Mohiaddin RH, Xu XY, Yacoub MHet al., 2012, Integrated morphologic and functional assessment of the aortic root after different tissue valve root replacement procedures, JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY, Vol: 143, Pages: 1422-+, ISSN: 0022-5223

Journal article

Foin N, Torii R, Mortier P, De Beule M, Xu Y, Davies J, Di Mario Cet al., 2012, OPTIMISATION OF RESULTS IN BIFURCATION STENTING: INSIGHTS FROM BENCH MODELS, COMPUTATIONAL SIMULATIONS AND 3D OCT, 61st Annual Scientific Session and Expo of the American-College-of-Cardiology (ACC), Publisher: ELSEVIER SCIENCE INC, Pages: E87-E87, ISSN: 0735-1097

Conference paper

Prapa S, Mccarthy KP, Kilner PJ, Xu XY, Johnson MR, Ho SY, Gatzoulis MAet al., 2012, Biomechanical perspectives of thoracic aortic aneurysm formation in patients with a bicuspid aortic valve: an integrated analysis, 2nd Congress of the European-Society-of-Cardiology Council on Basic Cardiovascular Science - Frontiers in Cardiovascular Biology, Publisher: OXFORD UNIV PRESS, Pages: S86-S86, ISSN: 0008-6363

Conference paper

Ma CYJ, Panoskaltsis N, Kumar R, Xu XY, Mantalaris Aet al., 2012, Simulation of ex vivo bone marrow culture: Application to chronic myeloid leukaemia growth model, BIOCHEMICAL ENGINEERING JOURNAL, Vol: 61, Pages: 66-77, ISSN: 1369-703X

Journal article

Wang Y, Pierce I, Gatehouse P, Wood N, Firmin D, Xu XYet al., 2012, Analysis of flow and wall shear stress in the peroneal veins under external compression based on real-time MR images, MEDICAL ENGINEERING & PHYSICS, Vol: 34, Pages: 17-27, ISSN: 1350-4533

Journal article

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