Elastic fibers, synthesis

Opitz F, Schenke-Layland K, Cohnert TU, Starcher B, Halbhuber KJ, Martin DP, and StockUA. Tissue engineering of aortic tissue Dire consequence of suboptitnal elastic fiber synthesis in vivo. Cardiovasc Res, 2004, 63, 719-730. 

Elastogenesis occurs primarily during late fetal and early neonatal periods. Elastin is synthesized and secreted from several cell types including smooth muscle cells, fibroblasts, endothelial cells, chondroblasts, and mesothelial cells (Uitto et al, 1991) with tissue-specific induction of elastin expression during development (Swee et al, 1995). After elastin has been deposited, its synthesis ceases and very little turnover of elastin is seen during adult life, unless the elastic fibers are subject to injury. In this case,... 

External forces applied to tissues lead to stretching of collagen, elastic fibers, and smooth muscle in the associated ECMs as well as proteoglycan deformation and fluid flow from within the matrix. The application of these forces ultimately leads to matrix remodeling and energy storage. The question arises as to how external mechanical events trigger cellular synthesis. 

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-... 

In order to convert the blocks with a molecular weight of about 2000 to linear macromolecules with molecular weights of 20,000 or more, they are first capped with a diisocyanate—normally of the aromatic type—and then expanded with a diamine or dihydroxy compound. Thus, the principal steps in the synthesis of elastic fiber molecules are ... 

Elastin is the other major protein of the extracellular matrix. Elastin molecules are cross-linked in the extracellular matrix, after synthesis and export by fibroblasts, to make networks of elastic fibers that provide elasticity to tissues. 

Tacryl . Acrylic fiber of a specific multi chain type. The structure conld he described as a Spider molecule with up to siit long straight linear legs which can orient independently and build up a fibrous structure. The molecular structure is built up by a controlled cross-linking process, so that Tacryl is like wool as it has a specific chain molecular interlinking which contributes to its mechanical and elastic properties. Synthesis of multichain polymers Schaefgen,... 

Elastic fibers are desired for certain textile areas of application, for example, for stockings and for overalls for sport. Such elasticity can be achieved by four methods the chemical synthesis of special fibers, physical modification of the molecular conformation, mechanical post-treatment of fibers and by special manufacturing procedures for textile materials. 

Not all copolymers which are produced by step-growth processes are random in nature. Block copolymers are also of major interest. An example of the synthesis of elastic polyurethane fibers was given in Section 1.5.4. Block and graft copolymers of polysiloxane-poly(alkylenc ethers) with segments like5-9 are used as surfactants in the production of polyurethane foams with uniform cell sizes. 

Wrobel-Kwiatkowska M, Zebrowski J, Starzyeki M, Oszmianski J, Szopa J (2007) Engineering of PHB synthesis causes improved elastic properties of flax fibers. Biotechnol Prog 23 269-277... 

EDFA (erbium-doped fiber amplifier), 341 EDTA (ethylene diamine tetraacetic acid) for polymeric gels synthesis, 89 solution process, 62, 63, 64 EDTA-EG technique as a polymerizable method, 89 gelation process, 89 EDX for bimetallic catalysts, 520 EELS studies on barium titanate, 85 elastic modulus, 250 eleclrocatalytic films, 94 electrochromic coatings, 292 films, 82... 

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