586 
HEMODYNAMICS 
turbidity development was inhibited by an order 
of magnitude. When albumin solution alone was 
in the oxygenator, small but rapid increases in 
relative turbidity by a factor of 1.2-1.3 occurred. 
The preparations of albumin used were sol- 
uble in solutions approximately 75% saturated 
with ammonium sulfate. This solubility of al- 
bumin alone was not altered by the oxygenator. 
The gamma globulin alone was completely pre- 
cipitated by this concentration of ammonium 
sulfate ; the gamma globulin was soluble in solu- 
tions approximately 30% saturated with am- 
monium sulfate. Gamma globulin which had 
been in the oxygenator showed a decrease in 
solubility in 30% ammonium sulfate solution. 
This decrease was related to the magnitude of 
the gas-liquid interfacial area exposure which 
had occurred. 
Albumin-globulin mixtures exposed to the 
oxygenator showed solubility properties inter- 
mediate between those of the individual pro- 
teins. The change in solubility properties which 
occurred in the mixtures took place within the 
first few minutes of oxygenator operation, as 
did the occurrence of small increases in turbid- 
ity of albumin alone. In the mixtures which had 
been in the oxygenator, albumin was found in 
both the supernatant and the precipitate which 
were produced by exposure to ammonium 
sulfate solution. 
These data were interpreted as indicating 
that the gas-liquid interfacial exposure of mix- 
tures of albumin and gamma globulin in the 
oxygenator resulted in production of a protein 
species which was not produced when either 
solution alone was in the oxygenator. The data 
show that this produced species contained both 
albumin and gamma globulin. Additional inter- 
pretation is that the first step in protein de- 
naturation which occurred in these experiments 
was unfolding of the gamma globulin molecule 
in the liquid-gas interface, and that a second 
step was the interaction of the unfolded mole- 
cule with another gamma globulin molecule. The 
latter molecule could have been either native 
or altered. In subsequent steps, unfolded gamma 
globulin molecules interacted with other ag- 
gregates to produce the observed large in- 
creases in turbidity and, ultimately, precipita- 
tion. The inhibition of turbidity development 
by an order of magnitude when albumin was 
present with gamma globulin may be inter- 
preted as indicating that denatured gamma 
globulin molecules interacted with albumin to 
produce a complex which did not aggregate 
further. Such a complex could account for the 
altered solubility properties in ammonium sul- 
fate which were observed after the mixtures of 
albumin and gamma globulin were exposed in 
the oxygenator. 
STUDY 3 
The purpose was to determine what presently 
available methods, with potential clinical use- 
fulness, could be utilized to decrease protein 
denaturation in the disc oxygenator. Making 
changes in the oxygenator oxygen tension, and 
changing the plasma protein initial composition, 
were considered, the former because of the 
work of Ashmore and associates,® and the latter 
because of the results with plasma protein 
fractions reported above. In addition, evaluation 
of a chemical with both hydrophobic and hydro- 
phillic properties, which conceivably could re- 
duce the interfacial forces acting on the glob- 
ulin molecule at the gas-liquid junction in the 
oxygenator, was considered. Nine, gross screen- 
ing procedures were carried out. The quantity 
of particulate matter which collected in the 
bubble trap of the pump-oxygenator system 
when plasma was oxygenated twenty hours was 
observed. This information was later used as a 
guide for additional procedures, with calves. 
Methods, Study 3 
Bovine plasma was used five times. In each 
instance, 4,000 cc of blood was drawn from a 
pregnant donor cow into standard ACD bags, 
using sterile technique. The blood was centri- 
fuged for ten minutes at 5° C at 4,200 RPM and 
the plasma was removed. 
A standard disc oxygenator, roller pump, 
heat exchanger, bubble trap, and venous res- 
ervoir system was set-up for each procedure. 
Clinical grade Tygon tubing was used. The 
arterial and venous lines from the pump-oxy- 
genator system were connected together to form 
a sterile, closed circuit. One thousand cc of 5% 
dextrose solution in one-half normal saline, 325 
