Jacques Ohayon, Ph.D.

Professor of Mechanics

 

University
University of Savoie
Polytech Annecy-Chambéry, Engineering School – 73376 Le Bourget du Lac – France

Composite Materials Department

Phone : (33) 479 75 8604
E-mail : Jacques.Ohayon@univ-savoie.fr

Laboratory
Laboratory TIMC-IMAG/DyCTiM, UJF, CNRS UMR 5525, In3S
Cellular/Tissular Dynamics and Functional Microscopy Team
Faculty of Medicine  of Grenoble
38706 La Tronche Cedex, France
Phone : (33) 456 52 0124
Fax : (33) 456 52 0022
E-mail : Jacques.Ohayon@imag.fr

Special Volunteer at NIH, 2007-2012
Molecular Cardiovascular Imaging Laboratory of Dr R.I Pettigrew NHLBI-NIH, Bethesda, 20814 MD, USA

 

 

Education

1992

HDR Mechanics, Robotic & Mathematical Modeling, University Paris 12, France

1985-1988

Visiting Fellow - Cardiac Mechanics, NIH, Washington D.C., USA

1982-1985

Ph.D. Cardiac Mechanics, University Paris 12, France.

1982

DEA  Fluid Mechanics, University of Compiègne (UTC), France

 

Fields of Interest

Atherosclerosis - Plaque rupture - Modulography - Elastography - Tissue growth - Cardiovascular mechanics - Biomechanics

Research Statement

The aims of our research on Cardiovascular Mechanics are to understand the evolution of atheroma plaque vulnerability and to increase knowledge of the plaque growth process through the combined use of mathematical modeling based on the nonlinear continuum mechanics theory, finite element method, together with clinical and biological investigations and micromanipulation techniques.

Recent Accomplishments on Biomechanics of Atherosclerotic Plaque

I.        Imaging in vivo the Atherosclerotic Vulnerable Plaque

II.       Atherosclerotic Plaque Rupture in Humans and Mice

III.     Arterial Wall Stiffness and Atherosclerosis

IV.     New Morphological Indexes for Atherosclerotic Plaque Rupture Prediction

V.       Residual Stress/Strain Distributions in Mouse and Human Atherosclerotic Plaques

VI.      Molecular Imaging and Atherosclerotic Plaques

VII.    Characterization of Atherosclerotic Plaque Components by AFM

VIII.   Micropipette Aspiration Technique Revisited for Quantifying Mechanical Properties of Biological Samples

Post-doctoral Scientists

•    2009-2012   Simon Le Floc’h, Ing., Ph.D

Doctoral Researches Performing by my Ph.D. students

•    Flavien Deleaval, Ph.D. student (2010-2013) working on Viscoelastic properties of atherosclerotic plaques. Supervisor: J. Ohayon and P. Clarysse. (E-mail : Flavien.Deleaval@imag.fr).


•    Adeline Bouvier, Ph.D. student (2010-2013) working on a New finite element approach for inverse problems in continuum mechanics: Application to the characterization of atherosclerotic plaques. Supervisor: J. Ohayon. (E-mail : Adeline.Bouvier@imag.fr).


•    Julie Heroux, Ph.D. student (2006-2012) working on New high affinity αvβ3 integrin targeted optical probe as a potential imaging biomarker for early atherosclerosis. Supervisors: J. Ohayon and R.I. Pettigrew. (E-mail : herouxj@nhlbi.nih.gov).


•    Nicolas Mesnier, Ph.D. student (2007-2011) worked on mechanical modelling of atheroma  plaque growth and angiogenesis processes. Supervisor: J. Ohayon and P. Tracqui.


•    Simon Le Floc’h, Ph.D. student (2005-2008) worked on Vulnerable atherosclerotic plaque elasticity reconstruction based on Coupling dynamical segmentation with optimization of strain measurements. Supervisors: J. Ohayon and G. Finet. (E-mail : Simon.Lefloch@imag.fr).


•    Alain Kamgoué, Ph.D. student (2005-2008) worked on Correlation-based quantification of intracellular strain propagation during cardiomyocyte contraction. Supervisors: J. Ohayon and P. Tracqui.


•    Thomas Boudou, Ph.D. (2004-2007) worked on an Extended modeling of the micropipette aspiration experiment for the characterization of the Young’s modulus and Poisson’s ratio of thin biological samples. Supervisor: J. Ohayon.

 

Selected Publications

•  Ohayon J, Mesnier N, Broisat A, Toczek J, Riou L, Tracqui P. Elucidating atherosclertic vulnerable plaque rupture by modeling cross substitution of ApoE-/- mouse and human plaque component stiffnesses. Biomechanics and Modeling in Mechanobiology. (in press), 2011.

•  Ohayon J, Gharib AM, Garcia A, Heroux J, Yazdani SK, Malvè M, Tracqui P, Martinez MA, Doblare M, Finet G, Pettigrew RI. Is arterial wall-strain stiffening and additional process responsible for atherosclerosis in coronary bifurcations? in vivo Study Based on Dynamic CT and MRI. Am J Physiol Heart Circ Physiol. 301(3):H1097-106, 2011.

• Broisat A, Toczek J, Mesnier N, Tracqui P, Ghezzi C, Ohayon J, Riou L. Assessing the low levels of mechanical stress in aortic atherosclerosis lesions from ApoE-/-mouse . Arterioscler Thromb Vasc Biol. 31(5):1007-10, 2011.

• Tracqui P, Broisat A, Toczek J, Mesnier N, Ohayon J, Riou L. Mapping elasticity moduli of atherosclerotic plaque in situ via atomic force microscopy . Journal of structural Biology 174(1):115-23, 2011.

•  Heroux J, Gharib AM, Danthi NS, Cecchini S, Ohayon J, Pettigrew RI. High Affinity avb3 Integrin Targeted Optical Probe as a New Imaging Biomarker for Early Atherosclerosis: Initial Studies in Watanabe Rabbits. Mol Imaging Biol., 12(1):2-8, 2010.

•  Peña E, Tracqui P, Azancot A, Doblare M, Ohayon J. Unraveling changes in myocardial contractility during human fetal growth: a finite element analysis based on in vivo ultrasound measurements. Ann Biomed Eng., 38(8):2702-15, 2010.

•  Mesnier N, Tracqui P, Ohayon J. An original force-displacement relationship fix spherical inclusions in multilayered viscoelastic finite media. Mechanics of Materials, 42(3):256-265, 2010.

•  Soloperto G, Keenan NG, Sheppard MN, Ohayon J, Wood N, Pennell DJ, Mohiaddin RH, Xu XY. A combined imaging, computational and histological analysis of a ruptured carotid plaque. Artery Research, 4(2):59-65, 2010

•  Le Floc'h S, Cloutier G, Finet G, Tracqui P, Pettigrew RI, Ohayon J. On the potential of a new IVUS elasticity modulus imaging approach for detecting vulnerable atherosclerotic coronary plaques: in vitro vessel phantom study. Phys. Med. Biol., 55:5701-5721, 2010.

•  Finet G., Huo Y, Riouffol G, Ohayon J, Guerin P, Kassab GS.  Structure-function relation in the coronary artery tree: from fluid dynamics to arterial bifurcations. EuroIntervention, 6:J10-J15, 2010.

•  Bourdarias C, Gerbi S, Ohayon J. A pseudo active kinematic constraint for a biological living soft tissue: An effect of the collagen network. Mathematical and Computer Modelling, 49(11-12): 2170-2181, 2009

•  Le Floc'h S, Ohayon J, Tracqui P, Finet G, Gharib AM, Maurice R, Cloutier G, Pettigrew RI. Vulnerable Atherosclerotic Plaque Elasticity Reconstruction Based on a Segmentation-Driven Optimization Procedure Using Strain Measurements: Theoretical Framework. IEEE Trans Med Imaging, 28(7):1126-37, 2009.

•  Kamgoué A, Ohayon J, Usson Y, Riou L, Tracqui P. Quantification of cardiomyocyte contraction based on image correlation analysis. Cytometry A, 75(4):298-308, 2009.

• Tracqui P, Ohayon J. An integrated formulation of anisotropic force-calcium relations driving spatio-temporal contractions of cardiac myocytes. Philos Transact A Math Phys Eng Sci., 367(1908):4887-905, 2009

•  Boudou T, Ohayon J, Picart C, Pettigrew RI, Tracqui P. Nonlinear elastic properties of polyacrylamide gels: implications for quantification of cellular forces. Biorheology, 46(3):191-205, 2009.

•  Kotys MS, Herzka DA, Vonken EJ, Ohayon J, Heroux J, Gharib AM, Stuber M, Pettigrew RI. Profile order and time-dependent artifacts in contrast-enhanced coronary MR angiography at 3T: origin and prevention. Magn Reson Med., 62(2):292-9, 2009.

• Tracqui P, Ohayon J, Boudou T. Theoretical analysis of the adaptive contractile behaviour of a single cardiomyocyte cultured on elastic substrates with varying stiffness. J Theor Biol., 255(1):92-105. 2008.

•  Tzvetkova-Chevolleau T, Stéphanou A, Fuard D, Ohayon J, Schiavone P, Tracqui P. The motility of normal and cancer cells in response to the combined influence of the substrate rigidity and anisotropic microstructure. Biomaterials, 29(10):1541-51, 2008.

•  Eskandari H, Salcudean SE, Rohling R, Ohayon J. Viscoelastic characterization of soft tissue from dynamic finite element models. Physics in Medicine and Biology, 53(22):6569-90, 2008.

•  Ohayon J, Finet G, Gharib AM, Herzka DA, Tracqui P, Heroux J, Rioufol G, Kotys MS, Elagha A, Pettigrew RI. Necrotic core thickness asnd positive arterial remodeling index: emergent biomechanical factors for evaluating the risk of plaque rupture. Am J Physiol Heart Circ Physiol., 295(2):H717-27, 2008

•  Kamgoue A., Ohayon J., Tracqui P. Estimation of cell Young’s modulus of adherent cells probed by optical magnetic tweezers: influence of cell thickness and bead immersion. J. Biomech Engin. ASME, 129(4):523-30, 2007.

•  Ohayon J, Dubreuil O, Tracqui P, Le Floc'h S, Rioufol G, Chalabreysse L, Thivolet F, Pettigrew RI, Finet G. Influence of residual stress/strain on the biomechanical stability of vulnerable coronary plaques: potential impact for evaluating the risk of plaque rupture. Am J Physiol Heart Circ Physiol., 293(3):H1987-96, 2007.

•  Tracqui P., Ohayon J. Rotational microrheology of multiplayered finite elastic media. Journal of Applied Physics, 102:171-176, 2007

•  Boudou T., Ohayon J., Arntz Y., Finet G., Picart C., Tracqui P. An extended modeling of the micropipette aspiration experiment for the characterization of the Young’s modulus and Poisson’s ratio of adherent thin biological samples: Numerical and experimental studies. Journal of Biomechanics, 39:1677-85, 2006.

•  Boudou T., Ohayon J., Picart C., Tracqui P. Characterization of the Young’s modulus and Poisson’s ratio of polyacrylamide gels using micropipette aspiration technique. Biorheology, 43(6): 721-8, 2006.