496 
HEMATOLOGY 
only with the male. It is a sex-linked, inherited 
irregularity. Observing hemophilia in dogs 
served as another approach to research. The 
colony of animals developed and housed by Ken- 
neth M. Brinkhous and his associates'^ at the 
University of North Carolina is a record in 
high adventure in nursing ailing animals and 
finding out the nature of their difficulty. 
Through breeding experiments, he and his asso- 
ciates were able to produce hemophilia A like 
disease in female dogs. Dogs with Factor IX de- 
ficiency are also known. A more detailed sum- 
mary of this work is given by Brinkhous.^ 
I want to refer to another nuance in this field 
of research. It was convenient to take blood 
from human patients or hemophilic dogs, add 
plasma fractions, and see which ones restored 
the clotting time to normal. This provided an 
assay for Factor VIII activity. This might have 
been an exclusive way for testing blood frac- 
tions, but we managed to devise an equally reli- 
able test based on the use of purified blood com- 
ponents. This was called the platelet cofactor 
assay (Figure 3). We did not need animals or 
hemophiliacs to do our work. Now I encoun- 
tered the reverse of the "rat feeder attitude." 
This time I was dealing with nice reagents in 
test tubes and did not need animals for assays. 
However, when our results were not liked, the 
suggestion came through quite strongly: "But 
you have not actually performed tests on defi- 
ciency plasma ; therefore, you cannot be certain 
that you are measuring Factor VIII activity." I 
presume this "scientific strategy" helps create 
the kind of confusion a competent trial lawyer 
can deliberately feature. Actually, we worked 
with the deficient plasmas as well as the puri- 
fied coagulation components. One of the hall- 
marks of good experimental work is exploration 
by utilizing many avenues of approach. It has 
unfortunately been difficult to find funds for re- 
search with animals having hereditary disor- 
ders. 
Pigs with von Willebrand's disease were first 
discovered at the University of Missouri and 
described by Hogan, Muhrer, and Bogart." 
Such animals were found to have a long bleed- 
ing time and low levels of Factor VIII. Follow- 
ing infusion of plasma or serum, the Factor 
VIII levels were found to be considerably 
greater than could be accounted for on the basis 
of the amount of Factor VIII infused." Per- 
haps there is a von Willebrand stimulating fac- 
tor. Some years after the initial studies were re- 
corded, Albert Hogan, who was chairman of the 
department in which the work was done, ex- 
plained that no one was studying these pigs and 
he thought it might be best to destroy them. 
When my opinion was solicited, I urged him not 
to do it. Now, new information is being pro- 
duced and animals from this hereditary line are 
also being studied at the Mayo Clinic. With 
advancing age, a pig keeps on growing and 
proves to be a large animal for experimental 
work. 
Returning to studies on vitamin K, I select 
one of our experiments with the dog as an ex- 
ample (Figure 4). The prothrombin and auto- 
prothrombin III (factor X) concentration was 
measured while Dicumarol was administered in 
large amounts. The concentration of the two 
ACTIVATION TIME (MIN.) 
Figure 3. — Assay for Factor VIII. Thrombin formed 
from purified prothrombin complex in the presence of 
purified Ac-globulin (Factor V), platelet factor 3, 
0.01 M calcium chloride, and variable amounts of a 
platelet cofactor (Factor VIII) concentrate. Note that 
the thrombin yield depended upon the quantity of 
platelet cofactor added to the reaction mixture. At 
pH 7.2 and 37° C. 
