alpha-chymotrypsin and Hyaline-Membrane-Disease

Low levels of protease inhibitors have been found on the 1st day of life in IRDS infants. 19 IRDS infants were studied together with foetuses and control term and preterm infants. Alpha1-antitrypsin, antichymotrypsin and alpha2-macroglobulin were measured with the electroimmuno assay. IRDS infants had significantly reduced concentration of alpha-antitrypsin and antichymotrypsin on the 1st day, the level increasing to normal on the 2nd day. In foetuses alpha1-antitrypsin was normal, antichymotrypsin 2% and alpha2-macroglobulin 1/3 of the normal adult level. The protease inhibitors are increased in infants born after premature rupture of foetal membranes. The part, if any, played by protease inhibitors is not entirely understood. The inhibitors may, theoretically, be of some importance in the dissolution of the hyaline membranes, protect against pulmonary vasoconstriction, protect pulmonary tissue against leucocyte and macrophage proteolytic enzymes and inhibit the release of or counteract vasoactive substances that might take part in the development of shock in IRDS babies.

Topics: Age Factors; alpha 1-Antitrypsin; Alpha-Globulins; Chymotrypsin; Female; Fetal Membranes, Premature Rupture; Fetus; Humans; Hyaline Membrane Disease; Infant, Newborn; Infant, Premature; Macroglobulins; Pregnancy; Protease Inhibitors; Respiratory Distress Syndrome, Newborn

The incubation of lung tissue from premature infants with pulmonary hyaline membranes in fibrinolysis activating or fibrinolytically active solutions gave the following results. With streptokinase it was not possible to dissolve hyaline membranes (verification of the physiological lack of plasminogen in premature infants). The mean content of membranes after 24 hours showed to be 18.14 +/- 12.43% which almost corresponded to the control value of 20.24 +/- 10.54% after incubation in NaCl-solution. In comparison, solutions of plasmin, plasmin-activator or activator prepared from proactivator-plasminogen through activation with streptokinase led to a clear reduction in the membrane content, i.e. 11.00 +/- 6.50, 13.89 +/- 9.72, and 13.63 +/- 8.94%, respectively. A decrease in membranes equally strong to that after plasmin appeared after incubation for only 12 hours in trypsin (11.09 +/- 8.62%). Plasmin, plasmin-activator, and activator, but not streptokinase alone, caused also a considerable nonspecific proteolysis of the lung parenchyma which was equal to the trypsin effect, for example, with an only half as long incubation time. Since the lungs of premature infants contain the tissue activator of fibrinolysis we discuss the suggestion of Ambrus et al. (1974) to administer an injection of plasminogen to premature infants immediately after birth so that a spontaneous fibrinolysis can be favoured for developing hyaline membranes.

Topics: Chymotrypsin; Fibrinolysis; Humans; Hyaline Membrane Disease; In Vitro Techniques; Infant, Newborn; Lung; Male; Plasminogen; Plasminogen Activators; Streptokinase; Time Factors; Trypsin