Jay D. Humphrey

Bio: Jay D. Humphrey is an academic researcher from Yale University. The author has contributed to research in topics: Medicine & Aorta. The author has an hindex of 58, co-authored 274 publications receiving 13528 citations. Previous affiliations of Jay D. Humphrey include Texas A&M University & University of Michigan.

Mechanotransduction and extracellular matrix homeostasis

Abstract: Soft connective tissues at steady state are dynamic; resident cells continually read environmental cues and respond to them to promote homeostasis, including maintenance of the mechanical properties of the extracellular matrix (ECM) that are fundamental to cellular and tissue health. The mechanosensing process involves assessment of the mechanics of the ECM by the cells through integrins and the actomyosin cytoskeleton, and is followed by a mechanoregulation process, which includes the deposition, rearrangement or removal of the ECM to maintain overall form and function. Progress towards understanding the molecular, cellular and tissue-level effects that promote mechanical homeostasis has helped to identify key questions for future research.

Cardiovascular Solid Mechanics: Cells, Tissues, and Organs

Abstract: 1. INTRODUCTION. 1.1 Historical Prelude, 1.2 Basic Cell Biology, 1.3 The Extracellular Matrix, 1.4 Soft Tissue Behavior, 1.5 Needs and General Approach, 1.6 Exercises, 1.7 References. 2. MATHEMATICAL PRELIMINARIES 2.1 A Direct Tensor Notation, 2.2 Cartesian Components, 2.3 Further Results in Tensor Calculus, 2.4 Orthogonal Curvilinear Components, 2.5 Matrix Methods, 2.6 Exercises, 2.7 References, 3. CONTINUUM MECHANICS 3.1 Kinematics, 3.2 Forces, Tractions and Stresses, 3.3 Balance Relations, 3.4 Constitutive Formulations, 3.5 Boundary and Initial Conditions, 3.6 Exercises, 3.7 References, 4. FINITE ELASTICITY 4.1 Introduction, 4.2 Incompressible Isotropic Elasticity, 4.3 Solutions in 3-D Incompressible Elasticity, 4.4 Compressible Isotropic Elasticity, 4.5 Membrane Hyperelasticity, 4.6 Exercises, 4.7 References 5. EXPERIMENTAL METHODS 5.1 General Philosophy, 5.2 Measurement of Strain, 5.3 Measurement of Applied Loads, 5.4 Testing Conditions, 5.5 Parameter Estimation and Statistics, 5.6 Exercises, 5.7 References 6. Finite Element Methods 6.1 Fundamental Equations, 6.2 Interpolation, Integration, and Solvers, 6.3 An Illustrative Formulation, 6.4 Inflation of a Membrane, 6.5 Inverse Finite Elements, 6.6 Exercises, 6.7 References PART II - VASCULAR MECHANICS 7. THE NORMAL ARTERIAL WALL 7.1 Structure and Function, 7.2 General Characteristics, 7.3 Constitutive Framework, 7.4 Experimental Methods, 7.5 Specific Constitutive Relations, 7.6 Stress Analyses, 7.7 Exercises, 7.8 References 8. VASCULAR DISORDERS 8.1 Hypertension, 8.2 Intracranial Aneurysms, 8.3 Atherosclerosis, 8.4 Aortic Aneurysms, 8.5 Additional Topics, 8.6 Exercises, 8.7 References 9. VASCULAR ADAPTATION 9.1 Mechanical Preliminaries, 9.2 Cellular Responses to Applied Loads, 9.3 Arterial Response to Hypertension, 9.4 Arterial Response to Altered Flow, 9.5 Vessel Response to Injury, 9.6 Veins as Arterial Grafts, 9.7 Aging, 9.8 Exercises, 9.9 References PART III CARDIAC MECHANICS 10. THE NORMAL HEART 10.1 Structure and Function, 10.2 General Characteristics, 10.3 Constitutive Framework, 10.4 Constitutive Relations, 10.5 Stress Analyses, 10.6 Exercises, 10.7 References 11. EPILOGUE APPENDICES I. Nomenclature, Abbreviations, and Conversions II. Results for Curvilinear Coordinates III. Material Frame Indifference 11. CARDIAC DISORDERS 11.1 Ischemia 11.2 Volume Overload 11.3 Hypertrophy 11.4 Cardiac Aneurysms 11.5 Additional Topics

A constrained mixture model for growth and remodeling of soft tissues

Abstract: Not long ago it was thought that the most important characteristics of the mechanics of soft tissues were their complex mechanical properties: they often exhibit nonlinear, anisotropic, nearly inco...

Cardiovascular solid mechanics

Abstract: The first € price and the £ and $ price are net prices, subject to local VAT. Prices indicated with * include VAT for books; the €(D) includes 7% for Germany, the €(A) includes 10% for Austria. Prices indicated with ** include VAT for electronic products; 19% for Germany, 20% for Austria. All prices exclusive of carriage charges. Prices and other details are subject to change without notice. All errors and omissions excepted. J.D. Humphrey Cardiovascular Solid Mechanics

Determination of a constitutive relation for passive myocardium: I. A new functional form.

Abstract: The specific aim of this study is to determine a constitutive relation for non-contracting myocardium in terms of a pseudostrain-energy function W whose form is guided by both theory and experiment. We assume that the material symmetry of myocardium is initially and locally transversely-isotropic, and seek a W which depends upon only two coordinate invariant measures of the finite deformation. The specific functional form of such a W is inferred directly from experimental protocols in which one invariant is held constant while the other is varied, and vice versa. On the basis of data from families of these "constant invariant" tests on thin slabs of myocardium taken from the mid-walls of six canine left ventricles, we propose a new polynomial form of W containing only five material parameters.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Automated Solution of Differential Equations by the Finite Element Method: The FEniCS Book

Abstract: This book is a tutorial written by researchers and developers behind the FEniCS Project and explores an advanced, expressive approach to the development of mathematical software. The presentation spans mathematical background, software design and the use of FEniCS in applications. Theoretical aspects are complemented with computer code which is available as free/open source software. The book begins with a special introductory tutorial for beginners. Followingare chapters in Part I addressing fundamental aspects of the approach to automating the creation of finite element solvers. Chapters in Part II address the design and implementation of the FEnicS software. Chapters in Part III present the application of FEniCS to a wide range of applications, including fluid flow, solid mechanics, electromagnetics and geophysics.

Hyperelastic modelling of arterial layers with distributed collagen fibre orientations

Abstract: Constitutive relations are fundamental to the solution of problems in continuum mechanics, and are required in the study of, for example, mechanically dominated clinical interventions involving soft biological tissues. Structural continuum constitutive models of arterial layers integrate information about the tissue morphology and therefore allow investigation of the interrelation between structure and function in response to mechanical loading. Collagen fibres are key ingredients in the structure of arteries. In the media (the middle layer of the artery wall) they are arranged in two helically distributed families with a small pitch and very little dispersion in their orientation (i.e. they are aligned quite close to the circumferential direction). By contrast, in the adventitial and intimal layers, the orientation of the collagen fibres is dispersed, as shown by polarized light microscopy of stained arterial tissue. As a result, continuum models that do not account for the dispersion are not able to capture accurately the stress–strain response of these layers. The purpose of this paper, therefore, is to develop a structural continuum framework that is able to represent the dispersion of the collagen fibre orientation. This then allows the development of a new hyperelastic free-energy function that is particularly suited for representing the anisotropic elastic properties of adventitial and intimal layers of arterial walls, and is a generalization of the fibre-reinforced structural model introduced by Holzapfel & Gasser (Holzapfel & Gasser 2001 Comput. Meth. Appl. Mech. Eng. 190, 4379–4403) and Holzapfel et al. (Holzapfel et al. 2000 J. Elast. 61, 1–48). The model incorporates an additional scalar structure parameter that characterizes the dispersed collagen orientation. An efficient finite element implementation of the model is then presented and numerical examples show that the dispersion of the orientation of collagen fibres in the adventitia of human iliac arteries has a significant effect on their mechanical response.

Production of a tissue-like structure by contraction of collagen lattices by human fibroblasts of different proliferative

Abstract: Fibroblasts can condense a hydrated collagen lattice to a tissue-like structure 1/28th the area of the starting gel in 24 hr. The rate of the process can be regulated by varying the protein content of the lattice, the cell number, or the con- centration of an inhibitor such as Colcemid. Fibroblasts of high population doubling level propagated in vitro, which have left the cell cycle, can carry out the contraction at least as efficiently as cycling cells. The potential uses of the system as an immu- nologically tolerated "tissue" for wound hea ing and as a model for studying fibroblast function are discussed.

Gold nanoparticles in biology: beyond toxicity to cellular imaging

Abstract: Gold, enigmatically represented by the target-like design of its ancient alchemical symbol, has been considered a mystical material of great value for centuries. Nanoscale particles of gold now command a great deal of attention for biomedical applications. Depending on their size, shape, degree of aggregation, and local environment, gold nanoparticles can appear red, blue, or other colors. These visible colors reflect the underlying coherent oscillations of conduction-band electrons (“plasmons”) upon irradiation with light of appropriate wavelengths. These plasmons underlie the intense absorption and elastic scattering of light, which in turn forms the basis for many biological sensing and imaging applications of gold nanoparticles. The brilliant elastic light-scattering properties of gold nanoparticles are sufficient to detect individual nanoparticles in a visible light microscope with ∼102 nm spatial resolution. Despite the great excitement about the potential uses of gold nanoparticles for medical diag...