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Responses on soft tissue viscoelasticity and preconditioningin-vivo vs. in-vitro

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  • Responses on soft tissue viscoelasticity and preconditioningin-vivo vs. in-vitro

    >
    > Dear Biomch-l, below please find my original posting and the 5 responses
    >
    > > Dear Biomech-L
    > > I am a graduate student studying the viscoelasticity and preconditioning
    > > of rat skin in-vitro using uni axial cyclic stretch protocol.
    > > As a part of my research I would like to relate the results in-vitro to
    > > actual in-vivo properties, and therefore would like to know if you have
    > > any references to correlate in-vivo to in-vitro viscoelasticity and
    > > preconditioning, in any soft tissue?
    > > A summary of replies will be posted
    > > Thanks in advance
    > > Hagai Eshel
    >
    > Dear Hagai Eshel,
    > One source of information about this topic can be obtained from papers
    > published by A.H. Hoffman and P. Grigg (i.e., do a medline search on their
    > names). Grigg has published one study [Grigg P (1996) Stretch sensitivity
    > of mechanoreceptor neurons in rat hairy skin. J Neurophysiol 76(5):2886-95]
    > in which he reports the 2D stiffness moduli for rat hairy skin. In other
    > studies co-authored by Grigg and myself, we found that to achieve a
    > "pseudo-elastic" state, we had to pre-condition rat skin by stretching it
    > about 10 times at physiological levels of load.
    >
    > Partap S. Khalsa, D.C., Ph.D.
    > Asst. Prof. of Biomedical Eng. & Orthopaedics
    > S.U.N.Y. at Stony Brook
    >
    > Hi Hagai:
    >
    > Well, the issue you've raised is an old one and there is no definitive
    > answer on the utility or futility of preconditioning as it bears on
    > in vivo behaviour. Basically, one uses preconditioning for one of two
    > reasons:
    >
    > (i) It somehow puts the tissue in a structural/mechanical state similar
    > to that it would experience in vivo. This argument is usually
    > marshalled for tissues which undergo cyclic loading in vivo: say,
    > cardiovascular tissues, periodontal ligament, cartilage etc. It
    > really wouldn't apply to rat skin--even with frisky rats.
    >
    > (ii) It puts the tissue in some reproducible state which another
    > investigator could duplicate. Coupled with the reduced standard
    > deviations you get from preconditioning before data collection,
    > this argument has a lot of attraction. It's really a pragmatic
    > choice.
    >
    > In either case, you should be wary of supposing that any uniaxial test
    > in vitro will give you mechanical properties which truly reflect those
    > in vivo. First of all, rat skin is surely subject to biaxial loading.
    > Second, when any tissue is cut into samples and removed from the body,
    > the continuous collagen fibre network is cut and new constraints on
    > fibre movement are imposed by the gripping system. This will be
    > equally true in uniaxial or biaxial testing.
    >
    > Steve Waldman in my lab has some very provocative data on the role that
    > gripping with sutures or clamps plays in determining the mechanical
    > properties one see in biaxial testing of soft tissues--preconditioned
    > or not.
    >
    > Good luck with the work.
    >
    > Mike
    >
    > ================================================== ===========
    > J. Michael Lee, Ph.D.
    > Interim Director, Biomedical Engineering Programme
    >
    > Associate Professor of Biomaterials (902) 494-6734 (Voice)
    > Chair, Dept. of Applied Oral Sciences (902) 494-2527 (FAX)
    > Dalhousie University
    > 5981 University Avenue jmlee@is.dal.ca
    > Halifax, Nova Scotia (902) 494-2162 Tissue Mechanics Lab
    > Canada B3H 3J5 (902) 494-6784 Tissue Structure Lab
    > ================================================== ===========
    > That which is not good for the bee-hive
    > cannot be good for the bee.
    >
    > --Meditations of Marcus Aurelius
    > ================================================== ===========
    >
    > Dear Hagai,
    >
    > I don't mean to deter you, but your proposal is extremely difficult
    > for many reasons that you should at least be aware of. The main
    > problem is "preconditioning" itself is poorly understood. The
    > problems with in vivo skin testing mostly have to do with nonuniform
    > strain fields. Since I can't really do this discussion justice, I'll
    > refer you to Lanir's review article:
    > - Lanir Y. Skin Mechanics. In: Chien RSaS, ed. Handbook of
    > Bioengineering. New York: McGraw-Hill, 1986; 11.1-11.25.
    >
    > and the seminal artiles on quantifying the mechanical properties of
    > skin...
    > - Lanir Y, Fung YC. Two-dimensional mechanical properties of rabbit
    > skin-I. Experimental system. Journal of Biomechanics 1974; 7:29-34.
    > - Lanir Y, Fung YC. Two-dimensional mechanical properties of rabbit
    > skin-II. Experimental results. Journal of Biomechanics 1974;
    > 7:171-182.
    >
    > And here are some article on interesting methods for measuring
    > "biophysical" properties of skin in vivo (not the intrinsic mechanical
    > properties)...
    > - Enomoto DN, Mekkes JR, Bossuyt PM, Hoekzema R, Bos JD.
    > Quantification of cutaneous sclerosis with a skin elasticity meter in
    > patients with generalized scleroderma. J Am Acad Dermatol 1996; 35(3
    > Pt 1):381-7.
    > - Gniadecka M, Gniadecki R, Serup J, Sondergaard J. Skin mechanical
    > properties present adaptation to man's upright position. In vivo
    > studies of young and aged individuals. Acta Derm Venereol 1994;
    > 74(3):188-90.
    > - Henry F, Goffin V, Pierard-Franchimont C, Pierard GE. Mechanical
    > properties of skin in Ehlers-Danlos syndrome, types I, II, and III.
    > Pediatr Dermatol 1996; 13(6):464-7.
    > - Nikkels-Tassoudji N, Henry F, Pierard-Franchimont C, Pierard GE.
    > Computerized evaluation of skin stiffening in scleroderma. Eur J Clin
    > Invest 1996; 26(6):457-60.
    > - Pierard GE, Nikkels-Tassoudji N, Pierard-Franchimont C. Influence of
    > the test area on the mechanical properties of skin. Dermatology 1995;
    > 191(1):9-15.
    > - Viatour M, Henry F, Pierard GE. A computerized analysis of intrinsic
    > forces in the skin. Clin Exp Dermatol 1995; 20(4):308-12.
    > - Gniadecka M, Serup J. Suction Chamber Method for Measurement of Skin
    > Mechanical Properties: The Dermaflex. In: Jemec JSaGBE, ed.
    > Non-invasive Methods and the Skin. Boca Raton: CRC Press, 1995;
    > 329-334.
    > - Fong SS, Hung LK, Cheng JC. The cutometer and ultrasonography in the
    > assessment of postburn hypertrophic scar--a preliminary study. Burns
    > 1997; 23 Suppl 1:S12-8.
    > - Murray BC, Wickett RR. Correlations between Dermal Torque Meter,
    > Cutometer, and Dermal Phase Meter measurements of human skin. Skin
    > Research and Technology 1997; 3:101-106
    >
    >
    > If you're only interested in correlating simple in vivo and in vitro
    > measures with substantial disease states your goal may be attainable.
    > However, you have to be very careful not to obscure your results with
    > edge effects (due to grips etc) and poor choice of specimen location
    > and orientation (due to inhomogeneity and anisotropy).
    >
    > Good luck, I'd be very interested in your results,
    >
    > Kristen Billiar, Ph.D.
    > Organogenesis Inc
    > Canton, MA
    > kbilliar@organo.com
    >
    > Dear Hagai Eshel,
    >
    > There is a paper from Vogel (1982) in Bioeng. Skin, 3, 198-209 entitled
    > "Mechanical properties of rat skin as compared by in vivo and in in vitro
    > measurement".
    >
    > Good Luck.
    >
    > Hugues Lafrance, Ph.D.
    > Baxter Healthcare Corp
    > CVG/CVS RnD
    >
    > E-mail : hugues_lafrance@baxter.com
    >
    > please provide me with your responses. I am also interested in this question
    > Thanks
    > *************************************************
    > Tim Foutz,Ph.D.,PE
    > Associate Professor
    > Biomechanics
    > Dept. of Biological and Agr. Engineering
    > Driftmier Engineering Center
    > The University of Georgia
    > Athens, Ga 30602
    >
    > Everyone has a photographic memory
    > Some don't have film
    > .......RWMc
    >
    > **************************************************
    >
    > ---------------------------------------------------------------
    >
    > Subject: Re: Soft tissue viscoelasticity and preconditioning in-vivo vs.
    > in-vitro
    > Date: Thu, 4 Feb 1999 10:23:19 -0500
    > From: "Partap S. Khalsa, D.C., Ph.D."
    > Reply-To: partap.khalsa@sunysb.edu
    > To: BIOMCH-L@NIC.SURFNET.NL
    > Newsgroups: bit.listserv.biomch-l
    >
    > Dear Hagai Eshel,
    > One source of information about this topic can be obtained from papers
    > published by A.H. Hoffman and P. Grigg (i.e., do a medline search on their
    > names). Grigg has published one study [Grigg P (1996) Stretch sensitivity
    > of mechanoreceptor neurons in rat hairy skin. J Neurophysiol 76(5):2886-95]
    > in which he reports the 2D stiffness moduli for rat hairy skin. In other
    > studies co-authored by Grigg and myself, we found that to achieve a
    > "pseudo-elastic" state, we had to pre-condition rat skin by stretching it
    > about 10 times at physiological levels of load.
    >
    > Partap S. Khalsa, D.C., Ph.D.
    > Asst. Prof. of Biomedical Eng. & Orthopaedics
    > S.U.N.Y. at Stony Brook
    >

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