Relationships between the biomechanical properties, composition and molecular structure of connective tissues.

Biomechanical, biochemical and morphological methods have been used in combination as analytical tools in the study of normal and pathological tissue functions. The biochemical studies described have been performed in vitro on whole tissue preparations and on individual components of connective tissues. Enzymatic degradation has been used to selectively remove components from the tissues. Collagen is the main load-bearing component in muscle tendon and skin. The mechanical properties of the aorta appear to depend on an interaction between collagen and elastin. Membranes of purified, reconstituted collagen type I itself exhibits the visco-elastic behavior which is characteristic for tissues like muscle tendon and skin. Applicability of the methods is shown in two examples: The strength of skin samples from patients with osteogenesis imperfecta was found to be reduced, and the skin from the patients with the lowest strength contained the highest proportions of collagen type III. Moreover, the stability of molecular collagen type I was decreased. In samples of the intracranial arteria cerebri media obtained at autopsy from patients with rupture of intracranial aneurysms the wall thickness, dry defatted weight and ratio collagen type I/type III were increased. The diameter of the arteries was reduced.