Sialic acids in human gastric aspirates: detection of 9-O-lactyl- and 9-O-acetyl-N-acetylneuraminic acids and a decrease in total sialic acid concentration with age.
1. The total sialic acid content of human gastric aspirates was measured using a colorimetric assay. Care was taken to optimize the assay and to eliminate interference. 2. The sialic acid content of gastric aspirates collected under resting conditions from 77 patients with non-ulcer dyspepsia was found to decrease with age from > 100 micrograms/ml at 25 years and younger to < 20 micrograms/ml above 70 years of age. 3. Analysis of the sialic acids by gas chromatography, mass spectrometry and thin-layer chromatography showed the presence of N-acetylneuraminic acid and two O-acylated derivatives, 9-O-acetyl- and 9-O-lactyl-N-acetylneuraminic acids. These forms were predominantly glycosidically bound. 4. Thin-layer chromatographic analysis of individual aspirate samples showed that the O-acetylated sialic acids were present in all samples, with a maximum of 25% and a minimum of 5% of the total sialic acids.
University Department of Medicine, Bristol Royal Infirmary, U.K.
A P
AP
Corfield
S A
SA
Wagner
A
A
Safe
R A
RA
Mountford
J R
JR
Clamp
J P
JP
Kamerling
J F
JF
Vliegenthart
R
R
Schauer
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D005750:Gastric Juice / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012794:Sialic Acids / Q000032:analysis / Q000378:metabolism*
D012794:Sialic Acids; C025676:9-O-acetyl-N-acetylneuraminic acid; C011624:N-acetyl-9-O-lactylneuraminic acid