410 G. ROUSER et al. 

Figs. 192 and 193. From extracts of 0.3 ml of plasma obtained fiom a rabbit prior to and 3 days 
after injection with 2.5 mg/kg of nitrogen mustard to illustrate the marked fall in total free 
amino acids. 
Fig. 194. Extract of 100 mg of lymphocytes from chronic lymphatic leukemia after triethylene- 
melamine (TEM) to show the presence of a compound tentatively identified as y-glutamylcysteine, 
(arrow to right) and distinctly different from glutathione (arrow to left). 
system. At low dosage levels and as an initial phase of the response to higher dosages, 
the blood and tissue free amino acids may increase. Glutamic acid in particular and 
to a lesser extent aspartic acid tend to be increased in blood and tissues and the levels 
tend to be maintained even when there is an overall decrease of free amino acids. 
Following a transient initial increase in free amino acids, the free amino acid levels of 
blood and tissties tend to fall. This decrease may be very great and can amount to 
an almost complete loss of the free amino acid pool. A marked fall in free amino 
acids has been observed also as part of the response to chlorambucil and dimethyl- 
myleran (see part V). 
The levels of sulfur-amino compounds are altered to a great extent by nitrogen 
mustard. In humans a decrease of glutathione in both erythrocytes and leukocytes 
is observed, while in rabbits at the peak of the peripberal blood leukocyte response 
cysteine'may be decreasedin kidney and glutathione is decreased in spleen and bone 
marrow when there is a marked overall decrease in free amino acids (Figs. 172-174). 
References p. 447/448 
