FREE AMINO ACIDS OF BLOOD AND URINE 235 
SoupartT?® has been adopted for the whole arrangement of the data. An additional 
column is given, grouping the overall ranges of concentrations as measured by the ion- 
exchange chromatographic method. Fig. 5 shows graphically how Soupart’s data 
fit with the overall range of concentrations described by similar methods for 30 
normal adult subjects. Fig. 5 thus gives a general picture of our present knowledge 
of free amino acid levels in normal plasma. As can be seen, all data obtained by ion- 
TABLE IV 
FREE AMINO ACID PLASMA LEVELS IN 20 NORMAL FASTING CHILDREN 
15 coloured and five white; 9 months—2 years old. Values are expressed in yemoles/| 
(Dr: Hi: Vis!») 

Range Average 
Alanine 99-313 219 
Glycine 56-308 170 
Valine 57-262 127, 
Threonine 33-128 60 
Proline 51-185 II5 
Serine 24-172 Q2 
Lysine 45-144 87 
Leucine 45-155 75 
Taurine 19- OI 49 
Arginine II— 65 31 
Histidine 24-112 64 
Isoleucine 20— 94 44 
Phenylalanine 23-— 69 40 
Ornithine 10-107 40 
Glutamine 40-290 135 
Tyrosine Le —22 45 
Methionine 3-— 29 21 
a-Aminobutytic acid o- 17 5 
Aspartic acid o- 9 2 
fb-Aminoisobutyric acid O—' 22 5 
1-Methylhistidine oO oO 
3-Methylhistidine (o) oO 
Cystine 1/, O— 40 4 
$-Alanine Oo Oo 
a-Aminoadipic acid oO oO 

exchange method are in fairly good agreement despite the various origins of the 
subjects investigated. 26 well-identified free amino acids are found in human blood 
plasma, of which 20 are present in measurable amounts, the other six being present 
only as traces. Fig. 5 also shows amino acids whose concentrations fluctuate within 
a relatively large range and those for which the range of variation is narrower. As 
can be seen, variation ratios of normal concentrations may range between 1/, and 1/3. 
b) In normal healthy children. Data presented here have been collected by Dr. 
H. Vis in a composite group of 20 children, boys and girls: five Western-European 
and 15 Central-African children, age range 9 months—2 years. Quantitative data are 
grouped in Table IV. Fluctuation ranges and average values are visualized in Fig. 6. 
There is no race-linked difference to be noticed. The plasma free amino acid concen- 
tration pattern of children is about the same as that found in adults. The decreasing 
References p. 261/262 
