Ebook Computational biophysics of the skin: Part 1
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (10.8 MB, 241 trang )
Prof. Cees W. J. Oomens
Eindhoven University of Technology, the Netherlands
“This book offers a fantastic approach to the non-invasive research of the skin. It
will be a valuable reference for not only students but also experts in skin research.”
Prof. Chil Hwan Oh
Korea University, South Korea
The accessibility of the skin in vivo has resulted in the development of noninvasive methods in the past 40 years that offer accurate measurements of skin
properties and structures from microscopic to macroscopic levels. However, the
mechanisms involved in these properties are still partly understood. Similar to
many other domains, including biomedical engineering, numerical modeling
has appeared as a complementary key actor for improving our knowledge of skin
physiology.
This book presents for the first time the contributions that focus on scientific
computing and numerical modeling to offer a deeper understanding of the
mechanisms involved in skin physiology. The book is structured around some skin
properties and functions, including optical and biomechanical properties and
skin barrier function and homeostasis, with—for each of them—several chapters
that describe either biological or physical models at different scales.
V421
ISBN 978-981-4463-84-3
Querleux
Bernard Querleux is senior research associate at the Worldwide
Advanced Research Center of L’Oreal Research & Innovation,
France. He obtained his doctorate in electronic engineering and
signal processing from the University of Grenoble, France, in
1987 and his habilitation in biophysics from Paris-Sud University,
France, in 1995. Since 2005, Dr. Querleux is serving as scientific
chairperson of the International Society for Biophysics and
Imaging of the Skin. Apart from being an expert in functional
brain imaging for the objective assessment of sensory perception,
his main research interests concern the development of new
non-invasive methods, including numerical modeling for skin
and hair characterization.
Computational Biophysics of the Skin
“This book presents an excellent overview of the state of the art in the computational
modeling of the skin, ranging from optical and biomechanical modeling to a
discussion on the skin barrier function and skin fluids. All chapters are written
by internationally well-known researchers in the field, each of them supplying a
comprehensive reference list for each chapter. It is an excellent read for anyone
starting in the field and also a very good source of information for experts.”
Computational
Biophysics of
the Skin
edited by
Bernard Querleux
Computational
Biophysics of
the Skin
1BO4UBOGPSE4FSJFTPO3FOFXBCMF&OFSHZ7PMVNF
Computational
Biophysics of
the Skin
editors
Preben Maegaard
Anna Krenz
Wolfgang Palz
edited by
Bernard Querleux
The Rise of Modern Wind Energy
Wind Power
for the World
CRC Press
Taylor & Francis Group
6000 Broken Sound Parkway NW, Suite 300
Boca Raton, FL 33487-2742
© 2015 by Taylor & Francis Group, LLC
CRC Press is an imprint of Taylor & Francis Group, an Informa business
No claim to original U.S. Government works
Version Date: 20140625
International Standard Book Number-13: 978-981-4463-85-0 (eBook - PDF)
This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher
cannot assume responsibility for the validity of all materials or the consequences of their use. The
authors and publishers have attempted to trace the copyright holders of all material reproduced in
this publication and apologize to copyright holders if permission to publish in this form has not
been obtained. If any copyright material has not been acknowledged please write and let us know so
we may rectify in any future reprint.
Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced,
transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or
hereafter invented, including photocopying, microfilming, and recording, or in any information
storage or retrieval system, without written permission from the publishers.
For permission to photocopy or use material electronically from this work, please access www.
copyright.com ( or contact the Copyright Clearance Center, Inc.
(CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been
granted a photocopy license by the CCC, a separate system of payment has been arranged.
Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and
are used only for identification and explanation without intent to infringe.
Visit the Taylor & Francis Web site at
and the CRC Press Web site at
To my wife, Sylvie
To my sons, Simon, Samuel, and Elie
Look at the invisible skin to understand
the visible skin
—Inspired by The Picture of Dorian Gray,
Oscar Wilde, 1891
“The true mystery of the world is the visible,
not the invisible”
Contents
Foreword
Preface
Part 1: Skin Color
1. Multilayer Modeling of Skin Color and Translucency
Gladimir V. G. Baranoski, Tenn F. Chen, and Aravind Krishnaswamy
1.1 Introduction
1.2 Measurement of Skin Appearance
1.3 Light Transport Simulation Approaches
1.3.1 Deterministic Simulations
1.3.2 Stochastic Simulations
1.4 Practical Guidelines
1.4.1 BioSpec Model Overview
1.4.2 Predictability
1.4.3 Reproducibility
1.5 Future Prospects
2. Dermal Component–Based Optical Modeling of Skin
Translucency: Impact on Skin Color
Igor Meglinski, Alexander Doronin, Alexey N. Bashkatov,
Elina A. Genina, and Valery V. Tuchin
2.1 Introduction
2.2 Skin Color Calculator
2.2.1 Online Object-Oriented Graphics-Processing
Unit—Accelerated Monte Carlo Tool
2.2.2 Graphics-Processing Unit Acceleration of MC
2.2.3 Online Solution
2.3 Skin Spectra and Skin Color Simulation
2.3.1 Basics of MC
xxi
xxiii
3
3
4
5
6
8
9
10
13
17
19
25
26
27
27
28
29
33
33
viii
Contents
2.3.2 Skin Model and Skin Tissues Optical
Properties
2.4 Modeling Results
2.5 Simulation of Skin Tattoo: Toward Its Effective
Removal
2.5.1 Introductory Remarks
2.5.2 Skin Model and MC Simulation
2.5.3 Skin Immersion Optical Clearing and
Tattoo Modeling
2.5.4 Results of MC Modeling and Discussion
2.6 Summary
3. Mathematics and Biological Process of Skin Pigmentation
Josef Thingnes, Leiv Øyehaug, and Eivind Hovig
3.1 Background
3.1.1 The Tanning Response
3.1.2 Photobiology of the UV Radiation
3.1.3 Signal Transduction
3.1.4 Melanogenesis
3.1.5 Melanin is Delivered to Nearby Keratinocytes
through Dendrites
3.1.6 Further Distribution through Keratinocyte
Movement
3.2 Mathematical Modelling of Pigment Production
and Distribution
3.3 Mathematics of Tanning
3.3.1 Available Data
3.3.2 Results
3.3.2.1 Reproduction of empirical data
3.3.2.2 Dendricity
3.3.3 Discussion
3.3.4 Methods
3.3.4.1 UV intensity and signal substance
dynamics
34
38
41
41
44
47
49
55
63
64
64
65
66
67
68
68
69
71
72
73
73
74
75
77
78
Contents
3.3.5 Melanin Production
3.3.5.1 Dynamics of dendrite length
3.3.5.2 Distribution of melanin as function
of dendritelength
3.3.5.3 Melanin dynamics within
keratinocytes
3.3.5.4 Estimates of parameter ranges
3.4 Conclusions
82
83
83
4. State-of-the-Art Constitutive Models of Skin Biomechanics
95
Part 2: Skin Biomechanics
79
79
80
Georges Limbert
4.1 Introduction
96
4.2 Modeling Approaches for Skin Biomechanics
98
4.3 A Brief on Continuum Mechanics
100
4.3.1 Kinematics of a Continuum
100
4.3.2 Constitutive Equations
102
4.4 Nonlinear Elastic Models of Skin
103
4.4.1 Models Based on the Gasser–Ogden–Holzapfel
Anisotropic Hyperelastic Formulation
103
4.4.2 Models Based on the Weiss’s Transversely
Isotropic Hyperelastic Formulation
105
4.4.3 Models Based on the Bischoff–Arruda–Grosh’s
Formulation
106
4.4.4 Models Based on the Flynn–Rubin–Nielsen’s
Formulation
106
4.4.5 Model Based on the Limbert–Middleton/
Itskov–Aksel’s Formulation
107
4.4.6 Model Based on the Limbert’s Formulation 108
4.5 Nonlinear Viscoelastic Models of Skin
112
4.5.1 Quasi-Linear Viscoelasticity and Its
Derivatives
112
4.5.2 Explicitly Rate-Dependent Models
113
4.5.3 Internal Variables Based on Strain
Decomposition
114
ix
Contents
4.5.4 Internal Variables Based on Stress
Decomposition
4.6 Other Inelastic Models of Skin
4.6.1 Softening and Damage
4.6.2 Plasticity
4.6.3 Growth
4.7 A State-of-the-Art Application: Skin Wrinkles
4.8 Conclusion
5. Fiber-Matrix Models of the Dermis
Cormac Flynn
5.1 Introduction
5.2 Characteristics of the Dermis
5.2.1 Physical Components
5.2.2 Mechanical Properties
5.2.3 In vivo Tension
5.3 Computational Fiber-Matrix Dermis Models
5.3.1 Statistical Distribution Models
5.3.2 Structural Models with Phenomenological
Uncrimping Representations
5.3.3 Eight-Chain Non-Gaussian Network
Models
5.3.4 Discrete Fiber Icosahedral Structural
Models
5.4 Discussion
6. Cellular-Scale Mechanical Model of the Human
Stratum Corneum
Roberto Santoprete and Bernard Querleux
6.1 Introduction
6.2 Stratum Corneum: Structure and Biomechanics
6.2.1 Structure
6.2.2 SC Biomechanics at the Macroscopic Scale
6.2.3 SC Biomechanics at the Microscopic Scale
6.3 Stratum Corneum Numerical Model
116
116
116
117
117
119
121
133
133
134
134
135
137
138
139
143
144
148
151
161
162
163
163
165
166
167
Contents
6.3.1
6.3.2
6.3.3
6.3.4
Structural Description
Mechanical Model
Estimation of Unknown Parameters
Relative Impact of the Three SC Major
Components
6.3.5 Simulation of Hydrated SC
6.4 Conclusion
174
176
178
7. Mathematical Models of Skin Permeability: Microscopic
Transport Models and Their Predictions
187
Part 3: Skin Barrier
Gerald B. Kasting and Johannes M. Nitsche
7.1 Introduction
7.2 Review of Layer-Specific Properties and Models
7.2.1 Stratum Corneum
7.2.2 Viable Epidermis
7.2.3 Dermis
7.3 Analysis of Three Stratum Corneum Microscopic
Transport Models
7.3.1 Stratum Corneum Microstructure
7.3.2 Transport Properties and Predictions
7.3.2.1 MIT model
7.3.2.2 UB/UC model
7.3.2.3 CAU model
7.3.3 Targets for Future Research
8. Cellular Scale Modelling of the Skin Barrier
Arne Nägel, Michael Heisig, Dirk Feuchter, Martin Scherer,
and Gabriel Wittum
8.1 Introduction
8.2 Motivation for a Stratum Corneum Geometry
Model with Tetrakaidekahedra
8.3 Tetrakaidekahedron Model
8.3.1 Parameters of a Tetrakaidekahedron
168
169
172
187
188
188
191
193
196
197
199
199
200
202
203
217
218
220
226
226
xi
xii
Contents
8.3.2 Parameter for the Lipid Matrix
Tetrakaidekahedron
8.3.2.1 Thickness of the lipid layer
8.3.2.2 Base edge length
8.3.2.3 Diameter
8.4 Mathematical Model
8.4.1 Model Equations
8.4.2 Periodic Identification for a Finite Number
of Layers
8.4.3 Periodic Identification for an Infinite
Number of Layers
8.4.4 Homogenization for an Infinite Number
of Layers
8.5 Computational Results
8.5.1 Example of a Transient Simulation
8.5.2 Theoretical Results for Homogenized
Membranes
8.5.3 Application
9. Molecular Scale Modeling of Human Skin Permeation
228
228
229
230
230
230
231
231
233
234
234
235
236
243
Sophie Martel and Pierre-Alain Carrupt
9.1 Introduction
244
9.2 Skin Barrier
246
9.2.1 Stratum Corneum: Composition and
Organization
246
9.2.2 Skin Permeability Pathways
247
9.3 Experimental Methods for Human Skin Permeability
Prediction
248
9.3.1 Ex vivo Human or Animal Skin
Permeability
248
9.3.2 In vitro Models to Predict Skin Penetration 249
9.3.2.1 Reconstructed skin from
keratinocytes
249
9.3.2.2 Artificial membranes
252
9.3.2.3 Chromatographic-based
approaches
254
Contents
9.4 In silico Models to Predict Skin Penetration
9.4.1 Reliable Data for Skin Prediction Models
9.4.2 Models Based on Molecular Properties
9.4.2.1 Models based on lipophilicity and
molecular size
9.4.2.2 Models considering H bond
capacities
9.4.2.3 Considering solubility parameters
9.4.2.4 3D-QSARs
9.4.2.5 Others models (non-linear)
9.5 Conclusion
10. Accessing the Molecular Organization of the Stratum
Corneum Using High-Resolution Electron Microscopy
and Computer Simulation
Lars Norlén, Jamshed Anwar, and Ozan Öktem
10.1 Introduction
10.2 Skin Lipids
10.3 Molecular Structure Determination in situ
10.3.1 The Procedure
10.3.2 Cryo-Electron Microscopy of Vitreous
Sections
10.3.3 Modeling and Simulation of the Skin Lipid
Organization
10.3.4 Toward a Complete Molecular Model of the
Stratum Corneum
10.3.5 Tomography of Vitreous Sections
10.4 Molecular Organization of the Skin Lipids and
Its Significance
10.5 Introduction to Modeling of Data and Simulation
10.6 Introduction to Electron Tomography 3D
Reconstruction
10.6.1 The 3D Reconstruction Problem in the
Linear Setting
10.6.2 Concept of Ill-Posedness and
Regularization
256
257
262
262
266
270
271
273
275
289
290
292
293
293
296
297
301
301
302
304
306
307
308
xiii
xiv
Contents
10.6.3
10.6.4
10.6.5
10.6.6
Ill-Posedness in ET
Reconstruction Methods
Early Development
Established Methods
10.6.6.1 Analytic methods
10.6.6.2 Iterative methods
10.6.6.3 Comparing analytic and iterative
methods
10.6.7 Recent Developments
10.7 Introduction to Electron Microscopy
Simulation
10.7.1 Usages of Simulation in EM Imaging in
Life Sciences
10.7.2 Present State of EM Simulators in Life
Sciences
10.7.3 Phantom Generator
10.7.4 Simulation of Image Formation
10.8 Future Perspective
10.8.1 3D Reconstruction for ET
10.8.2 Regularization Functionals
10.8.3 Noise Model and Regularization Parameter
10.8.4 Simultaneous Reconstruction and
Image Processing
10.8.5 Statistical Regularization
10.8.6 EM Simulation
Part 4: Skin Fluids and Components
11. Water Diffusion through Stratum Corneum
Bob Imhof and Perry Xiao
11.1
11.2
11.3
11.4
Introduction
Assumptions and Approximations
Notation and Abbreviations
Components of the Model
11.4.1 Skin-Side Properties
310
311
311
312
312
313
314
314
315
315
317
318
320
321
322
322
323
323
324
325
333
333
334
335
336
336
Contents
11.4.2 Air-Side Properties
11.4.3 Boundary Properties
11.5 SC/Air Interaction
11.6 Calculations
11.6.1 Skin-Side Calculation
11.6.2 Air-Side Calculation
11.6.3 Combined Model Calculation
11.7 Results and Discussion
11.7.1 Normal Volar Forearm SC Barrier
Property
11.7.2 Normal Volar Forearm SC Surface
Hydration
11.7.3 Effect of Tape Stripping
11.8 Further Developments
11.9 Conclusions
12. Accurate Multiscale Skin Model Suitable for Determining
the Sensitivity and Specificity of Changes of Skin
Components
337
338
339
340
340
341
342
342
343
344
345
348
349
353
Jürg Fröhlich, Sonja Huclova, Christian Beyer, and Daniel Erni
12.1 Introduction
354
12.3 Dielectric Properties of Constituents in
Human Skin
361
12.2 Brief Review on Skin Morphology and Composition
for Modeling
358
12.4 Features of the Dielectric Spectrum
12.5 Numerical and Semi-Analytical Modeling of Single
Biological Cells and Cell Suspensions
12.5.1 Modeling Effective Dielectric Properties
Using Mixing Formulas
12.5.1.1 Maxwell–Garnett
12.5.1.2 Hanai–Bruggeman
12.5.1.3 Landau–Lifshitz–Looyenga
12.5.2 Spectral Density Function Approach
362
364
364
364
365
365
366
xv
xvi
Contents
12.5.3 Three-Dimensional Modeling
366
12.5.4 Modeling of Tissue as a Composite
Material
368
12.6 Modeling Effective Dielectric Properties of
Materials Containing Diverse Types of
Biological Cells
369
12.6.1 Conclusions on Modeling Effective Dielectric
Properties of Materials Containing Diverse
Types of Biological Cells
373
12.7 Numerical and Semi-Analytical Modeling of
Multilayer Systems
374
12.8 Multiscale Approach
377
12.9 Sensitivity and Specificity Analysis
380
12.10Application to Human Skin
383
12.10.1A Preliminary Résumé on Appropriate
Models for Tissue Monitoring
386
12.11Conclusions
386
13. Model-Based Quantification of Skin Microcirculatory
Perfusion
Ingemar Fredriksson, Marcus Larsson, and Tomas Strömberg
13.1 Introduction
13.2 Model Description
13.3 Forward Calculation
13.3.1 Analytic Calculation of Single Shifted
Spectrum
13.3.2 Absorption Effects
13.3.3 Calculation of Doppler Power Spectrum
13.4 Inverse Problem
13.5 Accuracy and Sensitivity
13.6 In vivo Example
13.7 Discussion and Perspectives
13.7.1 Weaknesses and Strengths
13.7.2 Calibration
395
396
398
399
400
403
404
406
408
411
412
412
413
Contents
13.7.3 Extensions
13.7.4 Clinical Impact
13.8 Conclusions
Part 5: Skin Homeostasis
413
414
415
14. Graphical Multi-Scale Modeling of Epidermal
Homeostasis with EPISIM
421
Thomas Sütterlin and Niels Grabe
14.1 Introduction
14.2 Methods and Software Technologies
14.3 EPISIM Multi-Scale Modeling & Simulation
Platform
14.3.1 EPISIM Multi-Scale Model Architecture
14.3.2 EPISIM Modeller: The Graphical
Modeling System
14.3.3 EPISIM Simulator: The Multi-Agent–Based
Simulation Environment
14.4 Model of Human Epidermal Homeostasis
14.4.1 Cell-Center-Based Biomechanical Model
14.4.1.1 Optimal distance calculation
14.4.1.2 Cell migration based on
intercellular pressure,
cell–cell adhesion, and
basal membrane adhesion
14.4.2 Keratinocyte Cell Behavioral Model
14.4.2.1 Multi-scale cell cycle model
14.4.2.2 Multi-scale cell differentiation
model
421
424
426
426
428
433
434
435
436
438
439
441
443
14.4.2.3 Transepidermal water flux and
diffusion model
444
14.4.3.1 Multi-scale cell cycle simulation
447
14.4.2.4 Mitosis model
14.4.3 Multi-Scale Epidermis Simulation Results
445
446
xvii
xviii
Contents
14.4.3.2 Homeostatic epidermal in silico
tissue morphology
14.4.3.3 Transepidermal Ca2+ gradient
and barrier formation
14.4.3.4 Epidermal tissue kinetics
14.5 Discussion and Conclusion
14.6 Outlook
15. Heuristic Modelling Applied to Epidermal Homeostasis
François Iris, Manuel Gea, Paul-Henri Lampe,
and Bernard Querleux
15.1 Introduction
15.3 Problems Imposed by Enormous Variety of
Mechanisms to Be Considered
15.2 Structural and Functional Characteristics of
the Epidermis
15.3.1 Considerations Addressing the DEJ
15.3.2 Considerations Addressing Keratinocyte
Stratification and Differentiation
15.3.3 Considerations Addressing Pigmentation
15.3.3.1 Genetic aspects
15.3.3.2 Biochemical and structural
aspects
15.3.3.3 Melanosome trafficking
and degradation
15.3.4 Signalling and Epidermal Homeostasis
448
449
450
451
454
461
462
463
466
467
469
472
474
475
478
480
15.3.5 The Role of Scaffold Proteins in Directing
Transduction Pathways and Modulating
Signalling Cross-Talks
486
15.4.1 Problem of Relevance Attached to
Available Data
490
15.4 Approaching Dermatological Problems through
Systems Biology Principles?
15.4.2 Changing the Analytical Paradigm
15.5 The Mechanisms Whereby OA1 Differentially
Affects Melanosome Biogenesis and Motility
489
492
497
Contents
15.5.1 The Observed Facts
497
15.5.2 Event-Driven Data Integration and Negative
Selection of Working Hypotheses
499
15.5.2.1 The OA1-mediated mechanisms
in melanosome biogenesis
15.5.2.2 The OA1-mediated mechanisms
in melanosome motility
15.6 Conclusion
Index
499
503
505
525
xix
Foreword
We have learned much about skin. Starting in the 19th century,
the observations can truly be described as enlightenment.
Traditionally, this term is used for our basic knowledge in physics
and chemistry; however, it represents what occurred in skin
knowledge. The basics of anatomy, dissection, histology, cellular
anatomy, the cell, and the power of special stains propelled us to
what became possible in the 20th century.
The 20th century saw a rapid expansion, as the decades went
along, from a handful of laboratories to dozens of strong basic
and clinical science laboratories that took advantage of the start
of the 19th century knowledge. Special stains rapidly gained
prominence, followed by biochemistry, electron microscopy, and
eventually molecular biology.
By the end of the 20th century, the critical mass had been
reached that made this textbook possible.
The 21st century will see modeling become a main line part
of cutaneous science and many other areas of investigation.
In this textbook, Bernard Querleux has amassed a monumental
amount of information that had been widely dispersed and not
previously readily available to the passive and active scholar.
By dividing the book in broad sweeps, it becomes readily
absorbed. Scientists interested in color, mechanics, the inordinate
complexity of the many skin barriers, the numerous fluids, and
that all-encompassing area known as homeostasis will find welldisciplined packages that make for easy reading.
The limitation of this book’s scholar relates not to the power of
the computer or the programming but to the limitations of highquality biological observations that are currently available.
Whether at the subcellular, cellular, anatomic, functional
(physiology), pathologic, or pathology levels, the human brain,
programming, and the computer can do more than what is
available in terms of hard high-quality scientific observations.
xxii
Foreword
Much of this is in the realm of so-called big science obtaining
cooperative study groups to provide the data that is necessary to
predict with the power of the computer.
This volume will serve as the standard textbook for undergraduates, masters, and PhD students wishing to utilize the computer
and programs to understand the complexity of human cutaneous
biology.
It will likely be the source of dozens of masters and PhD theses
in the decades to come.
Because we are now at the critical mass and we have this
superb concise overview, we predict that the next decades will be
highly fruitful and will benefit many areas of science, in addition to
skin.
Howard I. Maibach, M.D.
The University of California School of Medicine
Department of Dermatology
San Francisco, California 94143-0989, USA
May 2014
Preface
For a long time, skin properties have been considered easy to
explore, as the skin is accessible to palpation and visual control.
If clinical exam remains the reference approach for individual
diagnosis, it has also shown its limits in reproducibility and
accuracy for quantifying skin properties, for instance, in clinical
studies aiming at characterizing chronological and photoaging,
skin specificity related to ethnic origins, and the evaluation of the
efficacy and safety of dermatological and cosmetic products.
Taking advantage of the accessibility of the skin in vivo, noninvasive methods were developed for about 40 years, which
nowadays offer accurate measurements of the skin color through
optical methods, firmness and elasticity measurements through
biomechanical devices, and even direct measurements of some skin
functions such as excretion, transepidermal water loss, perfusion,
and the barrier function. In vivo skin imaging has also appeared
in the past decades and gives us much information on the skin
structures from the microscopic to macroscopic levels.
However, we should admit that at the dawn of the 21st century,
the mechanisms involved in these properties are still partly
understood owing to the multidomain (biological, biochemical,
and biophysical domains) and multiscale dimension (cellular
and below to tissular and beyond) of the mechanisms. In many
domains, including biomedical engineering, numerical modeling
is nowadays recognized as a complementary key actor for
improving our knowledge.
This book presents for the first time the contributions that focus
on scientific computing and numerical modeling and simulations
to offer a deeper understanding of mechanisms involved in some
skin functions. The book is structured around some skin properties
and functions, with—for each of them—several chapters describing
either biological or physical models at different scales.
Part 1 is dedicated to skin optics. From skin color simulation
to the biology of skin pigmentation, these three chapters offer key
issues to modulate skin appearance.
xxiv
Preface
Part 2 deals with the biomechanical properties of the skin,
which are analyzed from the tissular scale toward the cellular
scale. These chapters bring new insights on the relative impact of
the main skin components on its non-linear biomechanical
properties.
One major function of the skin is to work as a protective barrier
against the penetration of external substances, allergens, and
microorganisms. Part 3 considers this function at different scales
and represents the state of the art in the understanding of skin
permeation.
Part 4 is focused on skin fluids, whose impact on the skin
physiology is very important but surprisingly have not been
studied much. Water behavior and state in the different skin layers
and a deeper description about skin microcirculation through
numerical simulation allow a better knowledge of some dynamic
properties of the skin physiology.
The last part of the book is more prospective and gathers two
chapters that introduce new modeling approaches based on the
“systems biology” approach. Aiming at integrating a large quantity
of data, the chapters discuss mathematical and non-mathematical
modeling of skin homeostasis.
I would like to thank all the authors for providing outstanding
contribution to this book and also for their support to this idea
that computational biophysics is a key approach to foster our
understanding of the physiology of organs such as the skin.
I am personally deeply grateful to Stanford Chong, from
Pan Stanford Publishing, who first suggested that I edit this
book and helped me broaden the covered topics. I don’t forget to
thank Sarabjeet Garcha and Arvind Kanswal from Pan Stanford
Publishing, not only for their great job concerning the publishing
but also for their permanent kindness to solve all the problems.
I hope this book will help all the readers, from master students
to confirmed researchers, coming from many disciplines such
as dermatology, cosmetic science, biology, chemistry, physics,
and computer science, in developing their own research of this
fascinating but complex organ, which is the human skin.
Bernard Querleux
May 2014
