BLOOD AND BLOOD DERIVATIVES — COHN 425 



proteins. The yields of the proteins in the various fractions are given 

 in table 3. 



The fractionation of plasma into its component parts according to 

 this process developed in the Department of Physical Chemistry of 

 the Harvard Medical School has been carried on in seven commercial 

 laboratories under contract with the United States Navy. The albumin 

 of plasma represents by far its largest component and is concentrated 

 therefore in its largest fraction, V. Whereas there is evidence of the 

 existence of more than one albumin, this fraction appears homogeneous 

 in the ultracentrifuge and in the electrophoretic apparatus at neutral 

 or slightly alkaline reactions. The standard of purity specified in the 

 Navy contracts for the production of this blood derivative permits 2 

 percent of globulin. Electrophoretic analyses reveal the constancy of 

 the product under the conditions of industrial production. 



Human serum albumin has been still further purified by crystalliza- 

 tion, and study of the crystallized albumin that we have prepared has 

 demonstrated that the very high thermal stability and low viscosity 

 of our standard preparations are indeed ascribable to the albumin, 

 instability largely to globulin and lipid impurities. 



Normal human serum albumin can be prepared in far larger amounts 

 and with higher yields if further purification by crystallization is 

 not superimposed upon the process. The standards of purity deter- 

 mined upon for the albumin now being delivered to the Navy in large 

 amounts were chosen so as to assure freedom from untoward reactions 

 with maximum efficiency in large-scale production. 



Serum albumin was developed in order to attain a blood derivative 

 which could be distributed in solution ready for immediate emergency 

 use. It has been made available as a 25-percent solution to render the 

 package as compact as possible for transport. Osmotically more than 

 four times as concentrated as plasma, 25-percent albumin is no more 

 viscous than whole blood. The package developed by the Armed 

 Forces for the standard 25-percent albumin solution occupies one-sixth 

 the space of the osmotically equivalent plasma package. 



ALBUMIN AND THE CONTROL OF THE BLOOD VOLUME 



That the value of plasma in controlling the volume of the blood 

 depends upon its osmotic activity is beautifully demonstrated by the 

 studies that have been carried out on the osmotic pressure of plasma 

 and of albumin solutions. These measurements yield a molecular 

 weight of 69,000 for albumin and an average weight of about 170,000 

 for the 40 percent of the protein which is not albumin. Each gram 

 of albumin is equivalent to 1.2 grams of plasma protein or to 20 cubic 

 centimeters of the current Red Cross citrated pooled plasma. The 

 volume of fluid held in the blood stream by each gram of albumin should 

 be about 18 cubic centimeters (table 4). 



