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Biomedical subjects

C Jakobs

Publications and source records attributed to C Jakobs.

At least 325 records · Page 18Linked to original sources
PubMed1984

Stable isotope dilution analysis of galactitol in amniotic fluid: an accurate approach to the prenatal diagnosis of galactosemia.

A stable isotope dilution assay for galactitol in amniotic fluid has been developed using selected ion monitoring chemical ionization gas chromatography-mass spectrometry of the hexaacetate derivative. [1,1-2H2]Galactitol was synthesized for use as the internal standard. Galactitol is a component of normal amniotic fluid with a mean concentration of 0.70 +/- 0.18 mumol/liter (n = 5). The amniotic fluid of a fetus with galactosemia had a concentration of 7.96 mumol/liter. Mannitol, sorbitol, and inositol were also found to be normal constituents of amniotic fluid. This stable isotope dilution assay is a rapid accurate method for measurement of galactitol in amniotic fluid for prenatal diagnosis of galactosemia.

Amniotic Fluid↗
PubMed1984

Identification of methyl-branched chain dicarboxylic acids in amniotic fluid and urine in propionic and methylmalonic acidemia.

3-Methyladipic, 4-methylpimelic, 4-methylsuberic, pimelic, and azeleic acids were identified by gas chromatography-mass spectrometry in the amniotic fluid of fetuses with propionic acidemia. These compounds were virtually undetectable in normal amniotic fluid. Concentrations much higher than those of the amniotic fluid were found in the urine of neonatal infants with propionic acidemia and methylmalonic acidemia. It appears that the accumulation of these compounds is a consequence of the accumulation of propionyl-CoA. Evidence was obtained for the presence of other methyl-branched chain dicarboxylic acids. 4-Methylpimelic acid and 4-methylsuberic acid have not previously been identified in human physiological fluids.

Amniotic Fluid↗
PubMed1983

Succinic semialdehyde dehydrogenase deficiency: an inborn error of gamma-aminobutyric acid metabolism.

Gamma-hydroxybutyric aciduria is a disorder of gamma-aminobutyric acid metabolism in which a compound of known neuropharmacologic activity accumulates. We have studied two patients in whom high levels of gamma-hydroxybutyric acid were found in blood, urine and cerebrospinal fluid. A coupled assay has been developed which estimates succinic semialdehyde dehydrogenase activity in isolated human lymphocytes. The mean activity of succinic semialdehyde dehydrogenase in a control and the four parents and two healthy siblings of these patients was 8.8 +/- 1.9 pmol . min-1 . mg-1 protein. In the patients the activities were 0.8 and 1.1 pmol . min-1 . mg-1 protein, approximately 9-13% of control. In the presence of saturating amounts of NAD+, lymphocyte sonicates, derived from the patients accumulated a significant amount of 14C-succinic semialdehyde from 14C-gamma aminobutyric acid, whereas none could be detected in controls. The data suggest a deficiency of succinic semialdehyde dehydrogenase in these patients, the first documented defect of the metabolism of gamma-aminobutyric acid in man.

4-Aminobutyrate Transaminase↗
PubMed1982

3-hydroxy-3-methylglutaryl-CoA lyase deficiency in an infant with macrocephaly and mild metabolic acidosis.

A girl, now three years old, is reported, in whom at the age of 5 months the diagnosis of 3-HMG-CoA lyase deficiency was established. The characteristic excretion pattern consisted of 3-HMG, 3-CH3-glutaconic acid, 3-CH3-glutaric acid and 3-HIVA. Activity of 3-HMG-CoA lyase in leucocytes was very low. She had compensated metabolic acidosis and mild hypoglycemia. Therapy with a leucine restricted diet decreased excretion of metabolites moderately but did not influence the tendency to metabolic acidosis. Clinically the infant presented with macrocephaly. At the age of 3 years she is severely retarded. CAT scan revealed the picture of progressive demyelination of the white matter.

Acidosis↗
PubMed1981

Valproic acid and several metabolites: quantitative determination in serum, urine, breast milk and tissues by gas chromatography-mass spectrometry using selected ion monitoring.

A method has been developed for the simultaneous quantitative determination of valproic acid (2-propylpentanoic acid) and its metabolites 2-propyl-2-pentenoic acid (trans), 2-propyl-3-pentenoic acid (trans), 2-propyl-4-pentenoic acid, 3-hydroxy-2-propylpentanoic acid, 4-hydroxy-2-propylpentanoic acid, 5-hydroxy-2-propylpentanoic acid, 3-oxo-2-propyl-pentanoic acid, and and 2-propylglutaric acid. All compounds were extracted at pH 5.0 with ethyl acetate. The concentrated extracts were trimethylsilylated and the resulting mixtures analyzed by a gas chromatography-mass spectrometry-computer system operated in the selected ion monitoring mode. Linear calibration curves were obtained in the concentration ranges studied (0.1-20 microgram/ml for metabolites, 0.1-150 microgram/ml for valproic acid. The recoveries of the drugs were between 92 and 97%. The relative standard deviations were between 3.9 and 8.1% (analysis of multiple 10-microliter samples of patient urine). The lower detection limits were found to be between 2.8 and 18 ng/ml using 200-microliter serum samples. The derivatized extracts were stable for at least one week. Applications of the method described include studies of placental transfer for valproic acid and metabolites in the human, the elimination of these substances by the neonate, their transfer via mother's milk, and their levels in mouse brain.

Adult↗
PubMed1978

Organic acid excretion in a patient with 3-hydroxy-3-methylglutaryl-CoA lyase deficiency: facts and artefacts.

The organic acid excretion in a patient with 3-hydroxy-3-methylglutaryl-CoA lyase deficiency is described. In addition to 3-hydroxy-3-methylglutaric, 3-methylglutaconic, 3-methylglutaric and 3-hydroxyisovaleric acids, substantial amounts of glutaric and adipic acids were repeatedly observed. 3-Methylcrotonic acid and possibly one of its isomers was found to be formed artificially from 3-methylglutaconic acid.

Acyl Coenzyme A↗
PubMed1978

Identification of metabolites of valproic acid in serum of humans, dog, rat, and mouse.

In kinetic studies of VPA in humans, dogs, rats, and mice, as well as in clinical routine analysis of serum concentrations of VPA in epileptic patients, 2--4 peaks (depending on the species examined) were regularly found in the gas chromatograms in addition to VPA. Comparison with control serum indicated that these peaks resulted from metabolism of VPA. By GC--MS, two of these metabolites could be identified as 5-hydroxy-2-propyl-pentanoic acid (5-OH-VPA) and 4-hydroxy-2-propyl-pentanoic acid (4-OH-VPA), using synthesized reference substances. Both metabolites results from omega (omega1, omega2) oxidation of VPA, 5-OH-VPA only occurring in serum of mice, and 4-OH-VPA in serum of mice and humans. With the aid of low- and high-resolution mass spectra, likely structures of the two remaining metabolites, both of which were found in serum of all the species examined, were proposed. One of these, 3-hydroxy-2-propyl-pentanoic acid (3-OH-VPA) confirms the involvement of beta-oxidation in the metabolism of VPA. The fourth metabolite, whose identity is uncertain, indicates a substance not described previously as a metabolite of VPA.

Adolescent↗
PubMed1977

Interlaboratory variability of valproic acid determinations.

19 pooled plasma specimens were sent as unknowns to 13 participating research laboratories. The interlaboratory variability between the results was very high. Only 4 out of 13 laboratories had 6--12% of their results within the 95% confidence limit for each sample. The precision of repeated determinations was fairly good. 6 out of 10 participating laboratories had a coefficient of variation of less then 5%. The reproducibility and the agreement between the different procedures for quantitative analysis of dipropylacetate is similar to that reported for other major antiepileptic drugs.

Laboratories↗
PubMedDate not supplied

Chemical analysis of succinylacetone and 4-hydroxyphenyllactate in amniotic fluid using selective ion monitoring.

A method for the measurement of the concentration of succinylacetone and 4-hydroxyphenyllactic acid in amniotic fluid was developed for the prenatal diagnosis of hereditary tyrosinemia. Succinylacetone was converted to 5-methyl-3-isoxazolepropionic acid and isolated with 4-hydroxyphenyllactic acid by liquid partition chromatography and the trimethylsilyl derivatives quantified by ammonia chemical ionization selected ion monitoring gas chromatography-mass spectrometry with 2-hydroxy-n-caproic acid as the internal standard. The concentration of 4-hydroxyphenyllactic acid in normal amniotic fluid was 1.97 +/- 0.75 (S.D.) mumol/l while succinylacetone was undetectable. A pregnancy at risk for tyrosinemia type II was monitored. The concentration of 4-hydroxyphenyllactic acid was within the normal range and a healthy child was born.

Amino Acid Metabolism, Inborn Errors↗