FREE AMINO ACIDS IN BLOOD. V 415 
changes in the plasma free amino acid levels are changes in three compounds: aspartic 
acid, glutamic acid, and taurine. 
Myleran produced changes in plasma free amino acid levels similar to those ob- 
served after administration of dimethylmyleran. After 10 mg of myleran per day 
for 10 days, patient Q. Tur. showed the typical drop in glutamic and aspartic acids 
and taurine. Some decrease of glycine and serine was evident also. After 10 mg of 
myleran per day for 10 days, the plasma of patient R. Tap. showed only the decreases 
of glutamic and aspartic acids and taurine. 
The taurine level of plasma returned to or near the control level very slowly. 
After treatment the patient’s free amino acid levels did not appear to return strictly 
to the original pretreatment levels. Prior to any form of treatment, the plasma free 
amino acid levels appeared to be higher. In particular, the glutamic acid levels were 
frequently above the normal levels. After treatment, there was a sharp decline and 
then a return toward the control levels for both aspartic and glutamic acids, but the 
levels seldom reached the levels observed before any form of treatment. This was 
observed in studies lasting for 100 days. It appears that there is a more or less per- 
manent effect on the plasma levels of glutamic and aspartic acids for unknown 
reasons. This factor must be considered when plasma samples are examined for 
deviations from normal associated with the leukemic process. Evidently the charac- 
teristically high glutamic acid level of the untreated patient may not be observed if 
the patient receives a drug. 
The free amino acid levels of blood were altered only when the drugs also produced 
a fall in the leukocyte count. Thus, an inactive pentane myleran (5 instead of 4 
carbons in the chain) that did not change the leukocyte count, failed to change the 
free amino acid levels of plasma, leukocytes, or erythrocytes. Similarly, an ineffective 
dose of the isomeric dimethylmyleran (CB 2432) failed to produce significant changes 
in either the leukocyte count or the free amino acid levels of the blood. The patient 
with chronic lymphatic leukemia that did not respond to a relatively large dose of 
dimethylmyleran with a reduction of the white cell count also failed to show any 
but the most minor changes in free amino acids of plasma. The changes in leukocytes 
were actually in the reverse direction of those seen in chronic granulocytic leukemia, 
that is, there was an increase in free amino acids in lymphocytes after dimethyl- 
myleran injection in contrast to decreases in the leukocytes of patients with chronic 
granulocytic leukemia. 
Effects of dimethylmyleran and myleran on erythrocyte free amino acid levels 
As with plasma, patients showed some variation in response. No effect was seen on 
the erythrocyte free amino acid levels of patient R. Tap. after 30 mg of dimethyl- 
myleran. The same patient did show, however, minimal effects after 40 mg of dime- 
thylmyleran. In this case there was a steady and marked fall in the taurine level and 
lesser decreases in alanine and glutamine. After 74 days, all but the taurine level had 
returned to pretreatment levels. Taurine was still very low 95 days after treatment. 
Another type of minimal effect was seen in patient H. Gol. the third time he received 
dimethylmyleran. The minimal changes in this case consisted of a decrease in glutamic 
acid, a lesser decrease of aspartic acid, and a considerable decrease of taurine. 
Intermediate effects on erythrocyte free amino acid levels were observed in patient 
M. Fal. after administration of 5 mg of dimethylmyleran. These changes consisted 
References p. 447/448 
