Ligaments components

Collagen synthesized in the absence of ascorbic acid (i.e. without hydroxyproline) cannot form its usual stable structure. Collagen is a major component of the structural and connective tissues of the body bone, cartilage, tendons, ligaments, teeth, and skin. Small wonder that things sort of fall apart in the absence of adequate ascorbic acid to support the activity of prolyl hydroxylase. 

Proteins are the third major class of biomolecules. The word protein comes from the Greek word proteios meaning primary. Protein is the primary material composing cells. Fifty percent of the human body is composed of proteins, and it is estimated that roughly 100,000 different proteins are found in humans. Protein is a major component of structural and connective tissue found in skin, ligaments, bones, muscles, and tendons. Digestive enzymes, insulin, and other hormones are proteins. 

Mesenchymal stem cells (MSCs) are multipotent cells that contribute to the regeneration of mesenchymal tissues such as bone, cartilage, muscle, ligament, tendon, adipose and marrow stroma [394517], [656539]. MSCs represent an important cellular component of the BM microenvironment [656703] and can be easily isolated from the adult BM stroma, where they represent a rare population of the cells (estimated at 0.001 to 0.01% of the nucleated cells, 10-fold less abundant than HSCs) [658632], [658640]. MSCs have also been found in umbilical cord blood, but not peripheral blood [658631]. Once isolated, MSCs can be expanded in culture through many generations, producing billions of MSCs for cellular therapy [656543]. 

Ascorbic acid as a water-soluble vitamin (vitamin C) is an essential component in the human diet. As one of many anti-oxidants (vitamin E and 3-carotene are examples of fat-soluble anti-oxidants), ascorbic acid is required for the growth and repair of tissues in all parts of the body. It is necessary to form collagen, an important protein used to make skin, scar tissue, tendons, ligaments, and blood vessels. 

Although proteins are large molecules they are small compared with a cell and even with supramolecular structures which may be part of a cell, such as plasma and organelle membranes, ribosomes, chromosomes, filaments, enzyme complexes and viruses (Chap. 1). Supramolecular structures are also prominent outside cells and are, for example, essential components of connective tissues such as tendon, ligament, cartilage and bone. Supramolecular structures can consist of a variety of different types of molecule from the small (such as membrane lipids) to macromolecules (such as proteins, DNA and RNA). 

The other major protein in the extracellular matrix is elastin, which is the main component of elastic fibers found in ligaments, large arteries, and lungs. After synthesis and partial hydroxylation of proline residues, a 72 kDa molecule of tropoelastin is secreted into the matrix. This protein is rich in nonpolar amino acids and contains repeating sequences, such as (Val-Pro-Gly-Val-Gly). These sections form an amorphous, random-coiled structure with frequent reverse turns. Other recurrent sequences are rich in alanine with paired lysine residues, e.g., -Ala-Ala-Ala-Ala-Lys-Ala-Ala-Lys-... 

Analysis of this components as suggested by Eq. 6 yields linear relationships of the specific Wy and Wjit terms as a function of ligament length (here not reported for shortness). From the intercept and the slopes of the linear regression lines, the terms Wg y and Wg can be obtained, that represent the yielding and the necking/tearing related components of the specific essential... 

The foreign body response to carbon fibers is not chronic unless they fragment. One major problem has been the accumulation of wear debris near the acetabular components [129]. However, when used as ligament replacements, carbon fibers appear to induce a type of fibrosis in which collagen fibers align with the fibers. This suggests that carbon fibers can be used as a template for the formation of fibrous tissue [130] and indeed tendon fibroblast cells have been grown on a... 

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