Biomedical subjects
Publications and source records attributed to F A Muskiet.
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A mass fragmentographic method for the determination of total cholesterol in serum using heptadeuterated [25,26,26,26,27,27,27-2H]cholesterol as internal standard is presented. The results obtained are compared with a colorimetric and gas chromatographic method which were previously proposed as reference methods. Criteria for the development of absolute measurement by means of mass fragmentography and stable isotopically labelled internal standards are given. The conclusion is drawn that, at present, mass fragmentographic methods for the determination of total cholesterol in serum do not fulfil the criteria required for absolute methods.
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We report the determination of catecholamines (dopamine, norepinephrine, and epinephrine) and their 3-O-methylated metabolites (3-methoxytyramine, normetanephrine, and metanephrine) in urine by gas chromatography/mass spectrometry, with use of stable isotopically labeled internal standards. Normal excretion values in terms of creatinine, expressed as a function of age, are given, together with results obtained for patients with neuroblastoma, ganglioneuroblastoma, pheochromocytoma, parkinsonism treated with L-DOPA plus peripheral decarboxylase inhibitor, and a patient with cardiogenic shock treated with dopamine. The results obtained for normal adults are discussed in relation to other catecholamine metabolites and mean overall catecholamine turnover.
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We report quantitative data on beta-glucuronidase- and sulfatase-hydrolyzable conjugates of homovanillic acid, 3,4-dihydroxyphenylacetic acid, p-hydroxyphenylacetic acid, and vanillic acid in the urine of 20 apparently normal and healthy control persons and of three patients with neuroblastoma. We used organic solvent extraction and capillary gas chromatography. There was considerable person-to-person variation in the conjugation percentages calculated. Mean conjugated percentages of the four compounds for 16 normal healthy persons 2.5--40 years of age were, respectively, 12%, 33%, 14%, and 35%. For newborns and patients with neuroblastoma, these percentages were somewhat different. Increased amounts of vanillic acid were found in the urine of the patients with neuroblastoma, but results of a small metabolic study in rats suggest that this increase most probably is of dietary origin.
We describe the determination of the 4-O-methylated catecholamine metabolites 4-methoxy-3-hydroxyphenylacetic acid (iso-HVA), 4-methoxy-3-hydroxyphenylmandelic acid (iso-VMA) and 4-methoxy-3-hydroxyphenylethylene glycol (iso-MOPEG) in urine with use of mass fragmentography and deuterated internal standards. Normal values, expressed in terms of creatinine, are given as a function of age. Urinary excretion values during neuroblastoma, pheochromocytoma, and parkinsonism treated with L-DOPA, and during the intravenous administration of dopamine are discussed. For normal persons, the mean percentages (+/- SD) of 4-O-methylated metabolites relative to their 3-O-methylated analogs were 6.29 +/- 2.79% (iso-HVA/HVA), 0.70 +/- 0.57% (iso-VMA/VMA), and 0.77 +/- 0.53% (iso-MOPEG/MOPEG). We observed no significant changes in these parameters for the patients studied and conclude that the determination of 4-O-methylated catecholamine metabolites for these patients does not add information to the results obtained from their quantitatively more important 3-O-methylated analogs.
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We describe the determination of 3-methoxy-4-hydroxy-phenylacetic acid, 3-methoxy-4-hydroxyphenylamandelic acid, and 3-methoxy-4-hydroxyphenylethylene glycol in amniotic fluid by means of mass fragmentography, with use of deuterated internal standards. The results expressed in terms of absolute concentration and creatinine concentration, are given as a function of gestational age. In the 15th to 17th week, concentrations in amniotic fluid are a reflection of those in the mother's serum, whereas in the 32nd to 40th week, these concentrations, expressed in terms of creatinine, are similar to those found in the urine of newborns. We discuss the possible usefulness of the determination of catecholamine metabolites in amniotic fluid in the diagnosis of congenital neuroblastoma, maternal pheochromocytoma, and underdevelopment.
We report the determination of 3-methoxy-4-hydroxyphenylpyruvic acid, 3,4-dihydroxyphenylmandelic acid, and 3,4-dihydroxyphenylethylene glycol in urine, by use of gas chromatography/mass spectrometry in combination with a simple purification method and deuterium-labeled internal standards. Normal excretion values in terms of creatinine, expressed as a function of age, are given, together with results obtained for patients with neuroblastoma, pheochromocytoma, or parkinsonism treated with L-DOPA + peripheral decarboxylase inhibitor, and for a patient receiving dopamine. We were unable to identify 3, 4-dihydroxyphenyllactic acid in urine. The results obtained and their relation to other catecholamine metabolites and catecholamine-precursor metabolites in urine are discussed.
We describe a mass-fragmentographic method for determination in urine of the following metabolites of L-3,4-dihydroxyphenylalanine and dopamine: vanillactic acid, 3,4-dihydroxyphenylacetic acid, 3-methoxy-4-hydroxyphenylethanol, and 3,4-dihydroxyphenylethanol. Deuterated analogs were used as internal standards. The method is fast, reproducible, sensitive, and selective, and does not require the use of time-consuming clean-up procedures. Normal excretion values in terms of creatinine, expressed as a function of age, as well as values obtained for patients with neurogenic tumors, a patient during therapy with L-3,4-dihydroxyphenylalanine, and a patient receiving dopamine are presented and discussed.
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We describe a ratio gas-chromatographic method for determination of cortisol production rate by measuring the isotope dilution of urinary cortisol metabolites. The method was calibrated by analyzing [3H]tetrahydrocortisol and [3H]tetrahydrocortisone of known specific activities. Results are reasonably well reproducible, the coefficients of variation ranging from 8-15% of allotetrahydrocortisol/tetrahydrocortisol and from 9-19% for tetrahydrocortisone. Correlation coefficients were 0.966 and 0.998 for tetrahydrocortisone and allotetrahydrocortisol/tetrahydrocortisol, respectively, when the method was compared with a method involving thin-layer chromatography and colorimetry. Only one chromatographic step is needed for both purification and quantitation, thus time and effort are saved.
Urinary acidic and alcoholic catecholamine metabolites were isolated separately from 24-h urines by simple extraction procedures. After derivatization, extracts were analyzed by means of simultaneous gas chromatography on two different stationary phases. The quality of the assay was checked by running "normal" and enriched commercial (Hyland) control urines in each series. Normal values are given for vanilmandelic acid, homovanillic acid, and 3-methoxy-4-hydroxyphenylethylene glycol, expressed as a function of age. We present excretion patterns showing these metabolites and also 3,4-dihydroxyphenylacetic acid, vanillacetic acid, 3,4-dihydroxyphenylethylene glycol, and vanilethanol for 12 patients with neurogenic tumors. Values obtained for vanilmandelic acid by this method correlate well with those obtained by the electrophoretic/colorimetric method of Hermann [Am. J. Clin. Pathol. 41, 373 (1964)].
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Bison pancreatic ribonuclease was isolated by affinity chromatography. Thermolysin and tryptic digestion of denaturated protein, and subtilisin digestion of native protein yielded peptides, which were purified and submitted to amino acid analysis. These peptides, together with partial sequence data obtained by Stewart & Stevenson (16) overlap the entire amino acid sequence of bison ribonuclease. No differences with bovine ribonuclease were found, although there may be differences in state of amidation of some residues.