THE AMINO ACIDS OF HUMAN SmAT

The microbiological methods used were those described previously by Hier and Bergeim (1, 2) and by Hier et ab. (3), except that threonine was determined with Streptococcus jaecalis according to Stokes et al. (4), since more consistent results were obtained with this organism than with Lactobacillus arabinosus.as previously used. However, we have found no difference in values when Streptococcus jaecalis or Lactobacdlus delbr~kii was substituted for Lactobacillus casei (used for arginine, phenylalanine, and tyrosine), Lactobacillus urabinosus (used for leucine, isoleucine, valine, and tryptophane), or Leuconostoc mesenteroides (used for lysine and histidine). The subjectsusedinallexperiments were male medicalanddental students ranging from 20 to 30 years of age. Unless otherwise stated in Tables I to VI, all subjects had a shower or bath no longer than 2 hours previous to the collection of the sweat sample. This was a precaution against variable accumulation of amino acids on the skin by evaporation. Specimens of sweat were collected by encasing the nude subjects in a rubber bag as far as their necks and seating them in a heat cabinet. Incandescent lamps furnished sufficient heat to obtain 100 to 200 cc. of sweat in 20 to 30 minutes. The collected sweat was then filtered through a medium porosity Berkefeld filter to remove dirt and dbbris. 10 cc. of this filtrate were diluted to 50 cc. for assay. 1 cc. of basal medium diluted to a final volume of 2 cc. with the sample and water was used in all cases. Now& V&ues-In Tables I and II, data are shown for normal subjects with slight variations in preparation of subjects, volume of collection, and after ingestion of tyrosine and histidine. In this series the first and second sweat samples for each subject were collected on different days. There