stic fiber 300x1.5nm 纔 stretch s hm
8
Entropic elasticity Image removed due to copyright considerations. See Figure 19-50 in: Alberts, Bruce, et al. Molecular Biology of the Cell. 4th ed. New York: Garland Publishing, 2002 Image may be viewed online at the NIH's PubMed Bookshelf. http://www.ncbi.nlm.nihgov/entrez/query.fcgi?db=books Elastin--note linearity small hysteresis Normally found intertwined with collagen. Image removed due to copyright considerations. See Figure 7. 2: 1 in: Fung, Y. C. Provides the "stretchiness"of tissues Biomechanics: Mechanical Properties of Living Tissues. New York: Springer-Verlag, 1993 Combination of single molecule characteristics and microscale structure
Entropic elasticity Elastin -- note linearity, small hysteresis. Normally found intertwined with collagen. Provides the “stretchiness” of tissues. Combination of singlemolecule characteristics and microscale structure. 9 Image removed due to copyright considerations. See Figure 19-50 in: Alberts, Bruce, et al. Molecular Biology of the Cell. 4th ed. New York: Garland Publishing, 2002. Image may be viewed online at the NIH's PubMed Bookshelf. Image removed due to copyright considerations. See Figure 7.2:1 in: Fung, Y. C. Biomechanics: Mechanical Properties of Living Tissues. New York: Springer-Verlag, 1993 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=Books
Canine aorta showing elastic fiber See Figure 19-49 in: Alberts, Bruce, et al. Molecular Biology of the Cell. 4th ed. New York: Garland Publishing, 2002. Image may be viewed online at the NIh's PubMed Bookshelf. http://www.ncbi.nlm.nihgov/entrez/query.fcgi?db Image removed due to Histological cross-section copyright considerations of a diseased carotid artery stained for smooth muscle cells Elastic response collagen response at Image removed due to igh degrees of copyright considerations H=hypertensive High wall stress leads to functional 10
Canine aorta showing elastic fiber content. Histological cross-section artery stained for smooth muscle cells. Elastic response initially, then stiff, collagen response at high degrees of extension. H=hypertensive High wall stress leads to functional remodeling! of a diseased carotid 10 Image removed due to copyright considerations. See Figure 19-49 in: Alberts, Bruce, et al. Molecular Biology of the Cell. 4th ed. New York: Garland Publishing, 2002. Image may be viewed online at the NIH's PubMed Bookshelf. Image removed due to copyright considerations. Image removed due to copyright considerations. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=Books
Lung parenchyma VON NEERGAARD EXPERIMEN Effect of Image removed due to liquid inflation copyright considerations Effect of of extension ension Relaxation pressure Mostly air, parenchyma mostly elastin and collagen. Proteoglycans(PGs)and glycosaminoglycanS (GAGs) a)GLYCOSAMINOGLYCANS (GAGs) form gels i) polysaccharide chains of disaccharide units i too inflexible and highly charged to fold in a compact way i strongly hydrophil iv) form extended conformations and gels v)osmotic swelling(charge repulsion) vi) usually make up less than 10% of ECM by weight vii)fill most of the ECM space vii) four main groups a hyaluronan b. chondroitin sulfate and dermatan sulfate C heparin sulfate and heparin d. keratin sulfate
Lung parenchyma Mostly air, parenchyma mostly elastin and collagen. Effect of collagen at high degrees of extension Mostly linear response at small extensions Effect of surface tension of gasliquid interface Proteoglycans (PGs) and glycosaminoglycans (GAGs) a) GLYCOSAMINOGLYCANS (GAGs) form gels i) polysaccharide chains of disaccharide units ii) too inflexible and highly charged to fold in a compact way iii) strongly hydrophilic iv) form extended conformations and gels v) osmotic swelling (charge repulsion) vi) usually make up less than 10% of ECM by weight vii) fill most of the ECM space viii) four main groups a. hyaluronan b. chondroitin sulfate and dermatin sulfate c. heparin sulfate and heparin d. keratin sulfate 11 Image removed due to copyright considerations Image removed due to copyright considerations
b) Proteoglycans(PGs) )aggrecan is a large proteoglycan in cartilage li decorin is secreted by fibro iv)PGs have varying amounts of GAGs v) PGs are very diverse in structure and content vi) PGs and GAGs can also complex with collagen vii) secreted proteoglycans have multiple functions vii) some PGs are not secreted ix) PG/GAGs have important roles in cell-cell Image removed due to copyright considerations. See Figure 19-39 in: Alberts. Bruce, et al. Molecular Biology of the Cell. 4th ed. New York: Garland Publishing 2002 Image may be viewed online at the NIh's PubMed Bookshelf. http://www.ncbi.nlm.nihgov/entrez/query.fcgi?db=books
b) Proteoglycans (PGs) i) form large aggregates ii) aggrecan is a large proteoglycan in cartilage iii) decorin is secreted by fibroblasts iv) PGs have varying amounts of GAGs. v) PGs are very diverse in structure and content vi) PGs and GAGs can also complex with collagen vii) secreted proteoglycans have multiple functions viii) some PGs are not secreted ix) PG/GAGs have important roles in cell-cell signaling 12 Image removed due to copyright considerations. See Figure 19-39 in: Alberts, Bruce, et al. Molecular Biology of the Cell. 4th ed. New York: Garland Publishing, 2002. Image may be viewed online at the NIH's PubMed Bookshelf. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=Books
Quick-freeze, deep-etch TEM of cornea(100, 000x) M. Johnson, J. Ruberti Image removed due to copyright considerations. Striations can be seen collagen fibers can be seen bridging collagen fibers See Figure 19-37 in: Alberts. Bruce, et al. molecular Biology of the cell. 4th ed. New York: Garland Publishing, 2002 Image may be viewed online at the NId's PubMed Bookshelf. http:/www.ncbi.nlmnihgov/entrez/query.fcgi?db=books
Quick-freeze, deep-etch TEM of cornea (100,000x) M. Johnson, J. Ruberti Striations can be seen on the collagen fibers. PGs can be seen bridging between the collagen fibers. 13 Image removed due to copyright considerations. Image removed due to copyright considerations. See Figure 19-37 in: Alberts, Bruce, et al. Molecular Biology of the Cell. 4th ed. New York: Garland Publishing, 2002. Image may be viewed online at the NIH's PubMed Bookshelf. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=Books
See Figure 19-36 in: Alberts, Bruce, et al. Molecular Biology of the Cell. 4th ed. New York: Garland Publishing. 2002 Image may be viewed online at the NIH's PubMed Bookshelf. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=books Aggrecan aggregate Keratin An aggrecan aggregate from fetal bovine cartilage
14 Image removed due to copyright considerations. See Figure 19-36 in: Alberts, Bruce, et al. Molecular Biology of the Cell. 4th ed. New York: Garland Publishing, 2002. Image may be viewed online at the NIH's PubMed Bookshelf. An aggrecan aggregate from fetal bovine cartilage. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=Books
Equilibrium Modulus of Adult Bovine Articular cartilage in Different lonic Strengths 1.2 TISSUE 808 0.6 0.4 Electrostatic:↑GAG Eo.2 Eisenberg and Grodzinsky1B-. J Orthop Res 3: 148 1985 0.001 0.01 lonic Strength, M Shear modulus Compression Load cell Nacl Torque Cell ∴∴:∵TsuE Base 16
TISSUE Electrostatic: GAG other TISSUE NaCl Shear Modulus 16
Shear Modulus:(Dynamic 05Hz, 0.8% strain 2.5 (B) 0.75 Dynamic G 2 1.5 0.5 Equilibrium G 0.25 0 (C) (Mean±sD,n=4 Dynamic Phase 17.5 0.01 0.1 lonic concentration M Like charge repulsion accounts for a large fraction(50%)of the stiffness in tissues with high GAG content These effects can be eliminated either by shielding (importance of Debye length --BE. 430 )with counter-ions or neutralization by changing pH 士
Shear Modulus: (Dynamic @ 0.5Hz, 0.8% strain) Jin+, Macromolecules, 2001 Equilibrium G Dynamic G Dynamic Phase Like charge repulsion accounts for a large fraction (~50%) of the stiffness in tissues with high GAG content. These effects can be eliminated either by shielding (importance of Debye length -- BE.430!) with counter-ions or neutralization by changing pH. + + + + + + + + + + + + + + + + + + + + + + + + + + + + 17
Table 19-3. Some Common Proteoglyeans Approximate Weight of Core Type of DI GAG Proteoglycan Protein GAG Chains Chains Functions Aggrecan 210.000 chondroitin --130 mechanical Betaglycan 36, COD chondroitin Irface binds TGF-8 40,000 widespread in binds to type connective collagen fibrils and TGF-B Perlecan 600.000 heparan 2.15 basal laminae sulfate chondroitin 10-15 package and surface Stress-Strain behavior of Kfe12 Peptide matrix Plastic mesh Linear behavior up to Leon, et al.. 1998 toughness due to small fracture strain
Linear behavior up to fracture Relatively low toughness due to small fracture strain Leon, et al., 1998 Stress-Strain Behavior of KFE12 18
