Collagen Fiber Structure Correlates With Mechanical Environment in Healing Myocardial Infarcts

2009 ◽  
Author(s):  
Gregory M. Fomovsky ◽  
Jeffrey W. Holmes
Keyword(s):  
Mechanical Properties ◽  
Ventricular Function ◽  
Rat Model ◽  
Collagen Fiber ◽  
Important Determinant ◽  
Collagen Fibers ◽  
Anisotropic Structure ◽  
Fiber Structure ◽  
Mechanical Environment ◽  
Time Points

Mechanics of healing myocardial infarcts are an important determinant of ventricular function. Large collagen fibers are the major contributors to the mechanical properties of healing scar. It has been suggested that an anisotropic structure, as observed in healing pig scars, may help preserve ventricular function, and that the alignment of collagen fibers could be guided by the regional mechanical environment in the infarct — in pig scars the alignment of collagen fibers was in the direction of greatest stretch [1]. By contrast, in the standard rat model of infarction we found that scars are structurally and mechanically isotropic at all time points in healing [2].

Functional implications of myocardial scar structure

1997 ◽  
Vol 272 (5) ◽  
pp. H2123-H2130 ◽  
Author(s):  
J. W. Holmes ◽  
J. A. Nunez ◽  
J. W. Covell
Keyword(s):  
Collagen Fiber ◽  
Circumferential Strain ◽  
Important Determinant ◽  
Scar Tissue ◽  
Collagen Fibers ◽  
Myocardial Scar ◽  
Radial Deformation ◽  
Fiber Structure ◽  
Coronary Ligation ◽  
Functional Implications

During healing after myocardial infarction, scar collagen content and stiffness do not correlate. We studied regional mechanics and both area fraction and orientation of large collagen fibers 3 wk after coronary ligation in the pig. During passive inflation of isolated, arrested hearts, the scar tissue demonstrated significantly less circumferential strain but similar longitudinal and radial deformation in comparison with noninfarcted regions of the same hearts. The observed selective resistance to circumferential deformation was consistent with the finding that most of the large collagen fibers in the scar were oriented within 30 degrees of the local circumferential axis. Furthermore, data from a previous study indicate that during ventricular systole these scars resist circumferential stretching, whereas they deform similarly to noninfarcted myocardium in the longitudinal and radial directions. We conclude that large collagen fiber structure is an important determinant of scar mechanical properties and that scar anisotropy allows the scar to resist circumferential stretching while deforming compatibly with adjacent noninfarcted myocardium in the longitudinal and radial directions.

Relationship Between Mechanical Properties and Collagen Structure of Closed and Open Wounds

1988 ◽  
Vol 110 (4) ◽  
pp. 352-356 ◽  
Author(s):  
Charles J. Doillon ◽  
Michael G. Dunn ◽  
Frederick H. Silver
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Collagen Fiber ◽  
Fiber Diameter ◽  
Normal Skin ◽  
Collagen Fibers ◽  
Collagen Structure ◽  
Collagen Network

Mechanical properties and collagen structure of excisional wounds left open are compared with wounds closed by clips. In both wound models, collagen fiber diameter increases with time post-wounding and is related to tensile strength. Clipped wounds show a higher ultimate tensile strength and tangent modulus compared with open wounds. In clipped wounds, newly deposited collagen appears as a biaxially oriented network as observed in normal skin. In open wounds a delay in the organization of the collagen network is observed and parallel wavy-shaped ribbons of collagen fibers are deposited. At long term, the high extensibility observed in open wounds may be due to the sliding of ribbons of collagen fibers past each other.

Study on the Preparation and Properties of Collagen Fiber- Polyurethane Composite Film

2011 ◽  
Vol 239-242 ◽  
pp. 3211-3215 ◽  
Author(s):  
Xing Yuan Ma ◽  
Yong Sheng Guo ◽  
Ling Yun Lu ◽  
Kun Jiang
Keyword(s):  
Mechanical Properties ◽  
Phase Separation ◽  
Water Vapor ◽  
Composite Film ◽  
Porous Structure ◽  
Collagen Fiber ◽  
Water Vapor Permeability ◽  
Collagen Fibers ◽  
Polymer Materials ◽  
Vapor Permeability

Chrome-tanned collagen fiber is the major solid waste of leather industry which is difficult to biological degradation and would caused serious pollution to the environment. However, the collagen fibers as a natural biological polymer materials, has unique properties of surface reactivity that the other polymer materials are not available. In this paper, the composite film of chrome-tanned collagen fiber- polyurethane (PU) were prepared is owing to H2O induced phase separation, and measured water vapor permeability, permeability, mechanical properties and microstructure. The results showed that the composite film of chrome-tanned collagen fiber-PU have continuous porous structure, which can improve the water vapor permeability and permeability of film, but reduce the mechanical properties of film. Thermal gravimetric analysis (TGA) showed that the thermal effect of collagen fiber and PU did not change significantly, so composite of collagen fiber and polyurethane by H2O induced phase separation belongs to physical process. The result demonstrates that this composite film has continuous porous structure, and collagen fibers with unique properties of surface reactions, so this material have potential applications in many fields.

Evolution of Scar Mechanical Properties During Myocardial Infarct Healing in Rat

2007 ◽  
Author(s):  
Gregory M. Fomovsky ◽  
Jeffrey W. Holmes
Keyword(s):  
Myocardial Infarction ◽  
Mechanical Properties ◽  
Rat Model ◽  
Important Determinant ◽  
Myocardial Infarct ◽  
Left Ventricular ◽  
Lv Function ◽  
Large Animal ◽  
Lv Dysfunction ◽  
Infarct Healing

The mechanics of healing myocardial infarcts are an important determinant of post-infarction left ventricular (LV) function and remodeling. Large animal infarct models are well studied; healing infarct scars have been shown to be mechanically and structurally anisotropic [1], and this anisotropy may help preserve LV function during some stages of healing [2]. At the same time, it has been suggested that the rat model of myocardial infarction is more similar to humans in the range of infarct sizes and observed LV dysfunction [3]. However, in the rat model, infarct mechanics and their effect on the overall LV function have not been described so far.

scholarly journals A method to analyze the influence of mechanical strain on dermal collagen morphologies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maximilian Witte ◽  
Michael Rübhausen ◽  
Sören Jaspers ◽  
Horst Wenck ◽  
Frank Fischer
Keyword(s):  
Mechanical Properties ◽  
Collagen Fiber ◽  
Ex Vivo ◽  
Second Harmonic ◽  
Mechanical Strain ◽  
Collagen Fibers ◽  
Collagen Network ◽  
Skin Sample ◽  
Fiber Network ◽  
Dermal Collagen

AbstractCollagen fibers and their orientation play a major role in the mechanical behavior of soft biological tissue such as skin. Here, we present a proof-of-principle study correlating mechanical properties with collagen fiber network morphologies. A dedicated multiphoton stretching device allows for mechanical deformations in combination with a simultaneous analysis of its collagen fiber network by second harmonic generation imaging (SHG). The recently introduced Fiber Image Network Evaluation (FINE) algorithm is used to obtain detailed information about the morphology with regard to fiber families in collagen network images. To demonstrate the potential of our method, we investigate an isotropic and an anisotropic ex-vivo dorsal pig skin sample under quasi-static cyclic stretching and relaxation sequences. Families of collagen fibers are found to form a partially aligned collagen network under strain. We find that the relative force uptake is accomplished in two steps. Firstly, fibers align within their fiber families and, secondly, fiber families orient in the direction of force. The maximum alignment of the collagen fiber network is found to be determined by the largest strain. Isotropic and anisotropic samples reveal a different micro structural behavior under repeated deformation leading to a similar force uptake after two stretching cycles. Our method correlates mechanical properties with morphologies in collagen fiber networks.

Experimental Investigation of Collagen Waviness and Orientation in Adventitia of Common Carotid Arteries of Rabbits

2012 ◽  
Author(s):  
Aristotelis Agianniotis ◽  
Nikos Stergiopulos
Keyword(s):  
Mechanical Properties ◽  
Structural Organization ◽  
Collagen Fiber ◽  
Carotid Arteries ◽  
Collagen Fibers ◽  
Angular Dispersion ◽  
Fluorescent Marker ◽  
Outermost Layer ◽  
Common Carotid Arteries ◽  
Fiber Organization

The adventitia is the outermost layer of blood vessels and its mechanical properties are determined by the organization of collagen fibers in this layer. The waviness and the angular dispersion characterize the collagen fiber organization. Previous studies were mainly conducted on loaded and chemically fixed vessels, which could modify the structural organization [1]. We have combined fluorescent marker with confocal microscopy and image analysis to quantify the waviness and angular distribution of collagen fibers, and determine the correlation between the waviness distribution of fibers and their main orientation in the adventitia of rabbit common carotid arteries at their zero-stress state.

A Review of the Collagen Orientation in the Articular Cartilage

Cartilage ◽  
2021 ◽  
pp. 194760352098877
Author(s):  
Roy D. Bloebaum ◽  
Andrew S. Wilson ◽  
William N. Martin
Keyword(s):  
Surface Layer ◽  
Articular Cartilage ◽  
Fiber Orientation ◽  
Collagen Fiber ◽  
Articular Surface ◽  
Imaging Techniques ◽  
Collagen Fibers ◽  
Deep Zone ◽  
Collagen Fiber Orientation ◽  
Critical Point Drying

Objective There has been a debate as to the alignment of the collagen fibers. Using a hand lens, Sir William Hunter demonstrated that the collagen fibers ran perpendicular and later aspects were supported by Benninghoff. Despite these 2 historical studies, modern technology has conflicting data on the collagen alignment. Design Ten mature New Zealand rabbits were used to obtain 40 condyle specimens. The specimens were passed through ascending grades of alcohol, subjected to critical point drying (CPD), and viewed in the scanning electron microscope. Specimens revealed splits from the dehydration process. When observing the fibers exposed within the opening of the splits, parallel fibers were observed to run in a radial direction, normal to the surface of the articular cartilage, radiating from the deep zone and arcading as they approach the surface layer. After these observations, the same samples were mechanically fractured and damaged by scalpel. Results The splits in the articular surface created deep fissures, exposing parallel bundles of collagen fibers, radiating from the deep zone and arcading as they approach the surface layer. On higher magnification, individual fibers were observed to run parallel to one another, traversing radially toward the surface of the articular cartilage and arcading. Mechanical fracturing and scalpel damage induced on the same specimens with the splits showed randomly oriented fibers. Conclusion Collagen fiber orientation corroborates aspects of Hunter’s findings and compliments Benninghoff. Investigators must be aware of the limits of their processing and imaging techniques in order to interpret collagen fiber orientation in cartilage.

Thrombopoietin improved ventricular function and regulated remodeling genes in a rat model of myocardial infarction

2013 ◽  
Vol 167 (6) ◽  
pp. 2546-2554 ◽  
Author(s):  
Kathy Yuen Yee Chan ◽  
Ligang Zhou ◽  
Ping Xiang ◽  
Karen Li ◽  
Pak Cheung Ng ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Ventricular Function ◽  
Rat Model

Processing of Nanoporous Gold by Dealloying and its Morphological Control

2007 ◽  
Vol 561-565 ◽  
pp. 1657-1660 ◽  
Author(s):  
Masataka Hakamada ◽  
Mamoru Mabuchi
Keyword(s):  
Mechanical Properties ◽  
Thermal Treatment ◽  
Acid Treatment ◽  
Nanoporous Gold ◽  
Anisotropic Structure ◽  
Ideal Strength ◽  
Pore Characteristics ◽  
Very High ◽  
Ligament Size ◽  
The Ideal

Nanoporous gold was fabricated by dealloying and their pore characteristics were further modified by thermal or acid treatment. The fabricated nanoporous gold had a ligament size of approximately 5 nm. Thermal treatment on the nanoporous gold increased the ligament size to approximately 500 nm. During the thermal treatment, ligaments are bonded across the cracks which had been generated during the dealloying. Acid treatment also increased the ligament size to approximately 500 nm; however, the acid treatment had a different effect on the pore characteristics from the thermal treatment. As a result, nanoporous gold prism microassembly with anisotropic structure was spontaneously fabricated by the acid treatment. The mechanical properties of nanoporous gold were also examined. It is estimated that the yield strength of nanosized ligaments in nanoporous gold is very high and close to the ideal strength of gold.

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