Biochemical aspect of dimethyl sulfide breath test in the studies on methionine metabolism.
Dimethyl sulfide concentration in expired alveolar gas (abb. alv-DMS) was determined following oral or intravenous administration of DL-, L- or D-methionine in healthy volunteers. Fasting level of alv-DMS was 1.9 +/- 1.3 ng/dl (mean +/- SD) in all the experimental subjects (N = 38). Following ingestion of 2.0 g of DL-methionine, alv-DMS increased to a peak of 37.1 +/- 21.7 ng/dl. Following administration of 1.0 g of D-methionine, the peak values of alv-DMS were 66.0 +/- 42.1 ng/dl (mean +/- SD) (orally) and 60.0 +/- 19.9 ng/dl (intravenously). In contrast, 2.0 g of L-methionine administration caused quite a little increase in alv-DMS; 4.6 +/- 2.6 ng/dl (orally) and 4.2 +/- 2.1 ng/dl (intravenously). In view of these results, it is apparent that the increase in alv-DMS following administration of methionine is certainly related to D-methionine metabolism. The threshold level for DMS exhalation in normal subjects was between 0.5 and 1.0 g for D-isomer and more than 2.0 g for L-isomer of methionine. Since the behavior of methyl mercaptan in expired alveolar gas (abb. alv-MM) was different from and disproportionate to that of alv-DMS, the increase in alv-DMS following D-methionine administration seemed to be caused by the mechanisms other than MM formation.
D000293:Adolescent; D000328:Adult; D001944:Breath Tests; D006801:Humans; D008297:Male; D008697:Methane / Q000031:analogs & derivatives; D008715:Methionine / Q000378:metabolism*; D008875:Middle Aged; D011650:Pulmonary Alveoli / Q000378:metabolism; D013440:Sulfides; D013997:Time Factors
D013440:Sulfides; D008715:Methionine; D008697:Methane; C004784:dimethyl sulfide