Biomedical subjects
Publications and source records attributed to S C Gates.
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Urine samples from 6- to 31-month-old male Fischer F344 rats were analyzed using a high performance liquid chromatograph and a unique computer-based data analysis and quality control system in order to discover substances that could be used as markers in the aging process. Metabolic profiles of the organic acids from these urines yielded 42 peaks whose areas could be measured reliably. Of the 42 peaks, 10 were found by analysis of variance to vary significantly (p less than 0.05) with age. Rats from the four ages could also be distinguished using a multivariate statistic (discriminant analysis).
Four methods for extracting organic acids from human urine prior to analysis by high-performance liquid chromatography (HPLC) were compared. The methods were manual solvent extraction with ethyl acetate and diethyl ether, continuous solvent extraction, anion exchange with pyridinium acetate as the eluting solvent and anion exchange with hydrochloric acid as the eluting solvent. All four methods produced samples that could be analyzed by reversed-phase HPLC, but the continuous solvent extraction and anion exchange with pyridinium acetate methods gave the best reproducibilities (approximately 6% relative standard deviations). Pretreatment of the urine with barium hydroxide and hydroxylamine hydrochloride prior to anion exchange did not markedly alter the HPLC profiles.
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The quantitative metabolic profiles of volatilizable components of human biological fluids, particularly urinary organic acids, is reviewed, with emphasis on the use of gas-chromatography/mass spectrometer/computer systems. Various definitions of metabolic profiling are considered and techniques for obtaining such profiles are discussed. The role of computer processing of such data is examined, and statistical techniques for treating quantitative metabolic profiles are suggested.
We describe a complete procedure for separation and mechanized analysis of organic acids in human urine. The acid fraction of urine is separated by anion-exchange chromatography on diethylaminoethyl-Sephadex. Individual acids are identified and measured by use of a gas-chromatography/mass spectrometer/computer system that can clearly distinguish contributions from at least 150 substances in a single sample. We discuss analytical recoveries, contributions from the sample separation process, stability of stored samples before and after processing, and reproducibility of the extraction procedure.
Normalized median, minimum, and maximum values (analytical concentration factors) are given for 134 organic acids in urine of nine adult control subjects, five juvenile control subjects, and five children with neuroblastoma. The organic acids, separated by anion-exchange chromatography, were analyzed by a gas chromatograph-mass spectrometer-computer system. Sixty substances in this fraction are positively identified, and, of these, mean absolute concentrations are listed for 20. An additional 81 substances, sought but not found by this method, and 16 other substances found in a subset of these urines by another analytical method, are also listed. Measured retention indices on 5% OV-17 and a selected discriminating ion are given for each of the total of 231 compounds. Results are compared for the three groups of subjects, and the value of normalizing the data is discussed.
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Our studies of a mentally retarded male with extremely elevated levels of alpha-aminoadipic acid and alpha-ketoadipic acid in his urine have led to the description of a new metabolic defect, alpha-ketoadipic aciduria. Analysis of the urine and serum from the patient's family revealed that the patient (KW) had a mentally and physically normal sister (CW) with the same metabolites elevated, but the rest of the family appeared normal.
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