Etude de la composition chimique de tissus humains de nature conjonctive en rapport avec I’âge: derme et aponévrose de la paroi abdominale, tendon d’Achille

Abstract

This article deals with the chemistry of 3 kinds of human connective tissue (dermis and aponeurosis of the abdominal wall, and the Achilles'' tendon) which were taken from 73 subjects of both sexes (35 male and 38 female), the ages ranging from the 5th month of intra-uterine life to 92 years. The contents of glucuronic acid (carbazole method) and aldoses (anthrone method) are determined as indices of the acid mucopolysaccharides and aldopolysaccharides respectively; the constitution of the latter is not entirely known. Moreover, the following amino acids were analyzed: arginine (index of protein content in the same tissue), tyrosine (index of biologically "active" proteins, mainly the cellular proteins), and hydroxyproline (index of collagen material). In some tests the amounts of nitrogen and carbon (index of organic substance) and of ash were also determined. The carbazole and anthrone methods gave values for the 3 tissues examined which fall during intra-uterine life; however, this fall continues gradually during the course of the 1st decade; concerning the dermis and aponeurosis, these values rise again towards the 6th decade, while in the tendon they remain almost constant. The tyrosine values also fall during fetal life, but this drop seems to continue later and does not increase in the aged. The level of hydroxyproline in the skin and aponeurosis increases during fetal life and reaches a fixed level shortly after birth; in the tendon, on the other hand, this fetal variation is slight. The arginine level remains constant. In the few cases studied we have observed no appreciable changes in the nitrogen and carbon content; the tissues furnished practically no ashes. The methods used for the determination of polysaccharides are not absolutely specific, but they nevertheless show the over-all changes in the connective tissues in respect to age. These ought, evidently, to be completed by a more precise analysis of the different polysaccharides in conjunctive tissues.