58 Essays in Biochemistry 



pile plasma or its derivatives for a major disaster. There is the further 

 difficulty that there is a significant deterioration rate for stored plasma. 



A still further major difficulty relates to the problem of processing 

 plasma. This is due to the fact that a certain percentage of the donor 

 population are carriers of the virus responsible for producing hepatitis. 

 It is obvious, then, that any pool of plasma enormously increases the 

 chances of spreading this disease. Thus far no practical effective 

 method has been found of inactivating this virus or of removing it 

 from plasma or its fractions. At best it is possible to minimize the 

 dissemination of this disease by processing and distributing plasma in 

 single units rather than in pools. For these various reasons the prob- 

 lem of finding effective plasma substitutes that could be used as plasma 

 volume expanders has arisen. 



Among the various proteins that have been tried are bovine albumin, 

 gelatin, isinglass, globin prepared from erythrocytes of man, and hemo- 

 globin. Attempts to despeciate various non-human proteins, such as 

 bovine albumin and isinglass, have not been successful in that effective 

 despeciation can only be achieved by means which are so drastic as 

 to cause extensive breakdown and loss of necessary molecular size. 

 Human globin, although free of the objectionable antigenicity or other 

 toxic properties, seems to be non-effective in the treatment of shock 

 probably because of rapid excretion. Hemoglobin, similarly, is un- 

 satisfactory. 



Gelatin has been accepted but is not entirely satisfactory for wide 

 use because those preparations which are of proper molecular size in 

 relation to retention in the blood stream are apt to gel at low tempera- 

 tures. Oxypolygelatin, an oxidized polymerized gelatin, has been in- 

 troduced by Pauling as a material of greater fluidity than gelatin but 

 similar physiological properties. There have been reports stating that 

 gelatin is antigenic in humans, but general experience with it has not 

 demonstrated this to be a serious factor in connection with its use. 



Of the various polysaccharides that have been considered, and these 

 have included pectin, methyl cellulose, and dextran, only the last has 

 found wide acceptance. Hazards of antigenicity or deficiencies of 

 staying power in those which have been degraded to remove anti- 

 genicity are associated with all the polysaccharides. In addition, there 

 is the difficulty that these materials may not be subject to the met- 

 abolic processes of the human body and may therefore remain deposited 

 in organs for undue lengths of time, leading to conditions such as 

 cirrhosis of the liver, which resulted from the use of the gum acacia 

 in the first world war. Although preparations of dextran have been 



