BLOOD AND BLOOD DERIVATIVES — COHN 435 



proteins of the plasma, are present in large amounts. The enzymes, 

 which regulate chemical reactions within the blood, and the hormones, 

 many of which have their origin in the various glands of the body 

 and vary in concentration from time to time, are present in but small 

 amount. Their regulatory functions generally involve other glands 

 or tissues in the body than those in which they originate. The poten- 

 tial value of each in therapy is as a specific concentrate. 



Coagulation of the blood by conversion of prothrombin to thrombin 

 and fibrinogen to fibrin clots, fibrin films, or fibrin foams. — The 

 mechanism by which the loss of blood from a wound or cut surface 

 is limited involves a series of proteins. Of these but two are essen- 

 tial to form the blood clot ; thrombin, present in the circulating blood 

 as a precursor prothrombin, and fibrinogen, the long asymmetric mole- 

 cule which is the structural element of the clot. 



Fibrinogen and thrombin are both separated in large amounts as 

 products of plasma fractionation. Fibrinogen can be prepared as a 

 thermosetting plastic or combined with thrombin in the form of 

 foams or films. 



Fibrin films resemble natural membranes in many respects and have 

 been employed as a protective layer for the central nervous system in 

 the repair of dural defects. 



Fibrin foam and thrombin has proven a valuable hemostatic agent 

 in neurosurgery, especially in the treatment of head injuries in this 

 war. 



Grouping of the blood by means of the isoagglutinins separated 

 as euglobulins. — The blood of a donor to be used in transfusion must 

 not be agglutinated by, or cause agglutination of, the blood of the 

 recipient. The plasma contains isoagglutinins, proteins, which when 

 separated from type-specific blood have been concentrated over thirty- 

 fold with respect to the plasma and utilized in the grouping of blood 

 for transfusion. 



Immune properties of the blood concentrated with the y-globulins 

 and made available for prophylaxis or modification of measles. — The 

 bearers of the immune properties of the blood are proteins, for the 

 most part y-globulins. The plasma collected by the American Red 

 Cross that has been fractionated yields albumin, fibrinogen, and 

 thrombin, the blood-typing globulins and the y-globulins as protein 

 concentrates, y-globulin, as distributed to the Armed Forces and to 

 public health agencies, through the American Red Cross, is concen- 

 trated twenty-five-fold with respect to plasma and has been found 

 to contain a large variety of the antibodies to the diseases common 

 to man. 



The studies that have been completed thus far have demonstrated 

 the value of this concentrate in the prophylaxis or modification of 

 measles. 



