Contraction Measurements Using Three-Dimensional Fibrillar Collagen

2021 ◽  
pp. 109-114
Author(s):  
James Griffith ◽  
William L. Berry
Keyword(s):  
Three Dimensional ◽  
Fibrillar Collagen

MECHANICAL BEHAVIOR UNDER UNCONFINED COMPRESSION LOADINGS OF DENSE FIBRILLAR COLLAGEN MATRICES MIMETIC OF LIVING TISSUES

2010 ◽  
Vol 10 (01) ◽  
pp. 35-55 ◽  
Author(s):  
SALAH RAMTANI ◽  
YOSHIYUKI TAKAHASHI-IÑIGUEZ ◽  
CHRISTOPHE HELARY ◽  
DIDIER GEIGER ◽  
MARIE MADELEINE GIRAUD GUILLE
Keyword(s):  
Mechanical Properties ◽  
Soft Tissues ◽  
Three Dimensional ◽  
Fibrillar Collagen ◽  
Unconfined Compression ◽  
Collagen Scaffolds ◽  
Collagen Concentration ◽  
Collagen Matrices ◽  
Compression Load ◽  
Living Tissues

Bio-artificial tissues are being developed as replacements for damaged biologic tissues and their mechanical properties are critical for load-bearing applications. Reconstituted dense three-dimensional (3D) fibrillar collagen matrices are promising materials for tissue engineering, at the light of their interaction with fibroblasts.1,2 The mechanical properties of these fibrillar collagen matrices are now being characterized under unconfined compression loading for various strain rates and collagen concentrations. The data were compared to those obtained in the same conditions with a biological tissue, the rat dermis. The results show a very sensitive behavior to both the displacement rate, typical of biological soft tissues, and the collagen concentration varying between 5 and 40 mg/ml. The link between the mechanical properties and the microscopic structure of the collagen scaffolds show an increasing viscoelastic modulus with respect to the fibril density. It is found that the matrices at 5 mg/ml and the dorsal rat skin (DRS) exhibit similar stress–strain response when submitted to the same external unconfined compression load. Such results highlight the interest of these matrices as potential tissue substitutes.

Platelet Interaction with Collagen Fibrils in Flowing Blood

1977 ◽  
Vol 37 (01) ◽  
pp. 001-016 ◽  
Author(s):  
Hans R. Baumgartner
Keyword(s):  
Three Dimensional ◽  
Rabbit Aorta ◽  
Flow Chamber ◽  
Collagen Fibrils ◽  
Unit Surface Area ◽  
Fibrillar Collagen ◽  
Interaction Patterns ◽  
Platelet Surface ◽  
Flowing Blood ◽  
Induced Aggregation

SummaryThe subendothelial surface of rabbit aorta and α chymotrypsin-digested subendothelium were exposed to anticoagulated human blood in an annular flow chamber. The wall shear rate was similar to that observed in large arteries (830 sec–1) and exposure times varied from 2½ to 40 min.The platelet reactive substrate of α chymotrypsin-digested subendothelium consists of a three-dimensional meshwork of collagen fibrils which form islands of variable size and height in a matrix of virtually unreactive elastin. Collagen-induced aggregation in the aggregometer was similar with or without prior α chymotrypsin-digestion of a highly dispersed preparation of fibrillar collagen. The rate of platelet adhesion was decreased on the fibrillar collagen of α chymotrypsin-digested subendothelium as compared to intact subendothelium. On the other hand the rate of aggregation was increased once platelets adhered to the fibrillar collagen. Mural thrombi (aggregates) disappeared on subendothelium whereas they grew progressively on the fibrillar collagen. Thus the fibrillar collagen of α chymotrypsin-digested subendothelium appears to be a more thrombogenic surface. It is suggested that physical (loose three-dimensional meshwork versus a comparatively solid surface) and/or chemical (number of platelet reactive sites per unit surface area) differences between the two surfaces may explain the platelet-surface-interaction patterns which are characteristic for each surface.

scholarly journals Physiological type I collagen organization induces the formation of a novel class of linear invadosomes

2012 ◽  
Vol 23 (2) ◽  
pp. 297-309 ◽  
Author(s):  
Amélie Juin ◽  
Clotilde Billottet ◽  
Violaine Moreau ◽  
Olivier Destaing ◽  
Corinne Albiges-Rizo ◽  
...  
Keyword(s):  
Matrix Metalloproteinase ◽  
Type I Collagen ◽  
Three Dimensional ◽  
Collagen Matrix ◽  
Matrix Metalloproteases ◽  
Collagen I ◽  
Matrix Metalloproteinase 2 ◽  
Type I ◽  
Fibrillar Collagen ◽  
Functional Relationships

Invadosomes are F-actin structures capable of degrading the matrix through the activation of matrix metalloproteases. As fibrillar type I collagen promotes pro-matrix metalloproteinase 2 activation by membrane type 1 matrix metalloproteinase, we aimed at investigating the functional relationships between collagen I organization and invadosome induction. We found that fibrillar collagen I induced linear F-actin structures, distributed along the fibrils, on endothelial cells, macrophages, fibroblasts, and tumor cells. These structures share features with conventional invadosomes, as they express cortactin and N-WASP and accumulate the scaffold protein Tks5, which proved essential for their formation. On the basis of their ability to degrade extracellular matrix elements and their original architecture, we named these structures “linear invadosomes.” Interestingly, podosomes or invadopodia were replaced by linear invadosomes upon contact of the cells with fibrillar collagen I. However, linear invadosomes clearly differ from classical invadosomes, as they do not contain paxillin, vinculin, and β1/β3 integrins. Using knockout mouse embryonic fibroblasts and RGD peptide, we demonstrate that linear invadosome formation and activity are independent of β1 and β3 integrins. Finally, linear invadosomes also formed in a three-dimensional collagen matrix. This study demonstrates that fibrillar collagen I is the physiological inducer of a novel class of invadosomes.

scholarly journals Origin of transparency in scattering biomimetic collagen materials

2020 ◽  
Vol 117 (22) ◽  
pp. 11947-11953
Author(s):  
Chrystelle Salameh ◽  
Flore Salviat ◽  
Elora Bessot ◽  
Miléna Lama ◽  
Jean-Marie Chassot ◽  
...  
Keyword(s):  
Mechanical Stability ◽  
Orientational Order ◽  
Three Dimensional ◽  
Fibrillar Collagen ◽  
Collagen Matrices ◽  
Biomedical Optical Imaging ◽  
Optical And Mechanical Properties ◽  
Living Tissues ◽  
Strong Scattering ◽  
Scatter Light

Living tissues, heterogeneous at the microscale, usually scatter light. Strong scattering is responsible for the whiteness of bones, teeth, and brain and is known to limit severely the performances of biomedical optical imaging. Transparency is also found within collagen-based extracellular tissues such as decalcified ivory, fish scales, or cornea. However, its physical origin is still poorly understood. Here, we unveil the presence of a gap of transparency in scattering fibrillar collagen matrices within a narrow range of concentration in the phase diagram. This precholesteric phase presents a three-dimensional (3D) orientational order biomimetic of that in natural tissues. By quantitatively studying the relation between the 3D fibrillar network and the optical and mechanical properties of the macroscopic matrices, we show that transparency results from structural partial order inhibiting light scattering, while preserving mechanical stability, stiffness, and nonlinearity. The striking similarities between synthetic and natural materials provide insights for better understanding the occurring transparency.

The orbit of Pluto over a long interval of time

1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer
Keyword(s):  
Periodic Orbit ◽  
Numerical Integration ◽  
Restricted Problem ◽  
Three Dimensional ◽  
The Third ◽  
Circular Restricted Problem ◽  
Resonance Relation

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

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