Matrix-assisted laser desorption/ionization mass spectrometry of discrete mass poly(butylene glutarate) oligomers

The mass dependency of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) response has been studied using equimolar mixtures of synthetic discrete mass poly(butylene glutarate) (PBG) oligomers of known structure having degrees of polymerization of 8, 16, 32, and 64. Mass discrimination observed was attributed to choice of matrix and detector saturation caused by higher laser intensity and inclusion of matrix ions in the MALDI spectra. Optimization of sample preparation and instrumental parameters provided uniform response over the mass ranged spanned by these four oligomers. The oligomer mixture was shown to serve as a model of more complex polymer distributions in the mass range 780-6000 Da, and application of the discrete mass oligomers as internal and calibration standards was demonstrated. Inclusion of PBG discrete mass oligomers as an internal standard in a quasi-equimolar mixture with polydispersed poly(butylene adipate) (PBA) indicated that some diminution of response occurred during the analysis of this mixture of materials. Reasons for differences in the corrected molecular weight averages of the polydispersed PBA obtained from measurements using MALDI and GPC were studied using individual discrete mass oligomers as calibration standards for GPC. The data indicated that differences in hydrodynamic volumes of PBG oligomers and PEG standards at similar masses resulted in an overestimation by GPC of the molecular weight averages of the PBA distribution.

L-2 hydroxyglutaric aciduria: proton magnetic resonance spectroscopy and diffusion magnetic resonance imaging findings

A 10-month-old boy was reported with the diagnosis of L-2 hydroxyglutaric aciduria. Amino acid chromatographic analysis revealed an 80-fold increase of hydroxyglutaric acid in the urine. Proton magnetic resonance (MR) spectroscopy of the brain obtained with the hybrid chemical shift imaging sequence (repetition time = 1,500 milliseconds, echo time = 40 milliseconds) revealed prominent peaks resonating at 2.50 ppm, which were attributable to L-2 hydroxyglutaric acid. Diffusion MR imaging was obtained using the echo-planar trace sequence (repetition time = 5,700 milliseconds, echo time = 139 milliseconds). Two different diffusion patterns were evident: a restricted diffusion pattern in the globi pallidi and an increased diffusion pattern in the white matter.

Quantification of 3-hydroxyglutaric acid in urine, plasma, cerebrospinal fluid and amniotic fluid by stable-isotope dilution negative chemical ionization gas chromatography-mass spectrometry

This paper describes a stable isotope dilution method for quantification of 3-hydroxyglutaric acid (3-HGA) in body fluids. The method comprises a solid-phase extraction procedure, followed by gas chromatographic separation and negative chemical ionization mass spectrometric detection. This method is selective and sensitive, and enables measurement of 3-HGA concentrations in urine-, plasma-, and CSF- samples of controls. The control ranges for 3-HGA were: urine 0.88-4.5 mmol/mol creatinine (n=12); plasma 0.018-0.10 micro mol/l (n=10), CSF 0.022-0.067 micro mol/l (n=10). We applied this method to measure 3-HGA in body fluids of three patients with glutaric aciduria type I. We also quantified 3-HGA in amniotic fluid of controls (range 0.056-0.11 micro mol/l; n=12) and in two samples from fetuses affected with glutaric aciduria type I.

Distribution of 14C-labelled carbon from glucose and glutamate during anaerobic growth of Saccharomyces cerevisiae

The distribution of carbon from glucose and glutamate was studied using anaerobically grown Saccharomyces cerevisiae. The yeast was grown on glucose (20 g l-1) as the carbon/energy source and glutamic acid (3.5 g l-1) as additional carbon and sole nitrogen source. The products formed were identified using labelled [U-14C]glucose or [U-14C]glutamic acid. A seldom-reported metabolite in S. cerevisiae, 2-hydroxyglutarate, was found in significant amounts. It is suggested that 2-hydroxyglutarate is formed from the reduction of 2-oxoglutarate in a reaction catalysed by a dehydrogenase. Succinate, 2-oxoglutarate and 2-hydroxyglutarate were found to be derived exclusively from glutamate. Based on radioactivity measurements, 55%, 17% and 14% of the labelled glutamate was converted to 2-oxoglutarate, succinate and 2-hydroxyglutarate, respectively, and 55%, 9% and 3% of the labelled glucose was converted to ethanol, glycerol and pyruvate, respectively. No labelled glucose was converted to 2-oxoglutarate, succinate or 2-hydroxyglutarate. Furthermore, very little of the evolved CO2 was derived from glutamate. Separation of the amino acids from biomass by paper chromatography revealed that the glutamate family of amino acids (glutamic acid, glutamine, proline, arginine and lysine) originated almost exclusively from the carbon skeleton of glutamic acid. It can be concluded that the carbon flow follows two separate paths, and that the only major reactions utilized in the tricarboxylic acid (TCA) cycle are those reactions involved in the conversion of 2-oxoglutarate to succinate.

Quantification of 3-methylglutaconic acid in urine, plasma, and amniotic fluid by isotope-dilution gas chromatography/mass spectrometry

A method is described for quantification of the trace metabolite, 3-methylglutaconic acid, by isotope-dilution gas chromatography/mass spectrometry using synthetic 3-[2,4,6-13C3]methylglutaconic acid. Results are shown for quantification of 3-methylglutaconic acid in plasma, urine, cerebrospinal fluid and amniotic fluid for both normal controls and patients with different forms of 3-methylglutaconic aciduria. A simple method for the synthesis and purification of 3-[2,4,6-13C3]methylglutaconic acid is also described.

Stable-isotope dilution analysis of D- and L-2-hydroxyglutaric acid: application to the detection and prenatal diagnosis of D- and L-2-hydroxyglutaric acidemias

A stable-isotope dilution assay has been developed for quantitation of D- and L-2-hydroxyglutaric acids in physiologic fluids. D- and L-2-hydroxyglutaric acids are separated as the O-acetyl-di-(D)-2-butyl esters. The method uses D,L-[3,3,4,4-2H4]-2-hydroxyglutaric acid as internal standard with ammonia chemical ionization, selected ion monitoring gas chromatography-mass spectrometry. For 13 patients with L-2-hydroxyglutaric aciduria, the concentrations of L-2-hydroxyglutaric acid were urine, 1283 +/- 676 mmol/mol creatinine (range, 332-2742; n = 12 patients); plasma, 47 +/- 13 mumol/L (range, 27-62; n = 8); cerebrospinal fluid, 62 +/- 30 mumol/L (range, 34-100; n = 6). In a child with D-2-hydroxyglutaric aciduria, the levels of D-2-hydroxyglutaric acid were urine, 1565 +/- 847 mmol/mol creatinine (range, 729-2668; n = 4); plasma, 61 +/- 14 mumol/L (range, 46-73; n = 3); cerebrospinal fluid, 15 and 25 mumol/L (n = 2). Control concentrations of D- and L-2-hydroxyglutaric acids were (D:L): urine (n = 18), 6.0 +/- 3.6 mmol/mol creatinine (range, 2.8-17): 6.0 +/- 5.4 (range, 1.3-19); plasma (n = 10), 0.7 +/- 0.2 mumol/L (range, 0.3-0.9): 0.6 +/- 0.2 (range, 0.5-1.0); cerebrospinal fluid (n = 10), 0.1 +/- 0.1 mumol/L (range, 0.07-0.3): 0.7 +/- 0.6 (range, 0.3-2.3). Investigation of control amniotic fluid (n = 10) revealed the following values (D:L): 1.2 +/- 0.4 mumol/L (range, 0.6-1.8): 4.0 +/- 0.7 (range, 3.1-5.2), suggesting the feasibility of prenatal diagnosis in families at risk.

3-Methylglutaconic aciduria: a marker for as yet unspecified disorders and the relevance of prenatal diagnosis in a 'new' type ('type 4')

The Mendelian disorder known as 3-methylgutaconic aciduria (McKusick 250950) gives evidence of allelic and locus heterogeneity. Type 1 has a mild clinical phenotype and confirmed 3-methylgutaconyl-CoA hydratase deficiency; inheritance is autosomal recessive. Other forms have major clinical manifestations and subdivide into X-linked (type 2), a form in Iraqi Jews with optic atrophy (so-called type 3); and untyped (putative autosomal recessive) forms without identified enzyme defects. In the latter, 3-methylglutaconic aciduria may simply be a marker for another metabolic disorder. We describe a male proband with 3-methylglutaconic aciduria designated here as 'type 4' (autosomal recessive, with severe psychomotor phenotype and cerebellar dysgenesis). He is the offspring of Italian consanguineous parents. Born with congenital malformations, he has been followed for 18 years, showing profound developmental delay and cerebellar dysgenesis. Measures of hydratase activity in cultured fibroblasts from the proband and 11 additional patients (two with type 1 disease, 9 with either type 2 or an unspecified form) revealed deficient enzyme activity in type 1 cases and normal activity in the proband and the other 11 cases. Two of the untyped cases probably have 3-methylglutaconic aciduria of the type described here. Prenatal diagnosis in the form described here may be feasible by analysis of amniotic fluid metabolites in pregnancies at risk if the mother does not entirely remove elevated concentrations. A female sibling of the proband had normal metabolite values in amniotic fluid. Postnatal follow-up confirmed absence of the disease. We give the normal values for amniotic fluid and results on these additional fetuses at risk (none affected).

Studies on new dehydropeptidase inhibitors. II. Structural elucidation and synthesis of WS1358A1 and B1

The structures of WS1358A1 and B1, new dehydropeptidase inhibitors isolated from Streptomyces parvulus subsp. tochigiensis No. 1358, have been established to be 2-hydroxy-2-hydroxyaminocarbonyl-3-methylglutaric acid (1) and 2-hydroxy-2-hydroxyaminocarbonylglutaric acid (2), respectively, on the basis of spectroscopic evidence and synthesis of the racemates.

3-Methylglutaconyl-CoA hydratase, 3-methylcrotonyl-CoA carboxylase and 3-hydroxy-3-methylglutaryl-CoA lyase deficiencies: a coupled enzyme assay useful for their detection

A coupled assay has been developed using 3-methylcrotonyl-CoA and NaH14CO3 which permits the detection of deficiencies of 3-methylcrotonyl-CoA carboxylase, 3-methylglutaconyl-CoA hydratase and 3-hydroxy-3-methylglutaryl CoA-lyase. The products of the reaction were analyzed by high performance liquid chromatography. Using this method the site of the defect was documented in a patient with deficiency of 3-methylcrotonyl-CoA carboxylase, 2 patients with deficiency of 3-methyl-glutaconyl-CoA hydratase, and 2 patients with deficiency of 3-hydroxy-3-methyl-glutaryl-CoA lyase.

Identification of 3-methylglutarylcarnitine. A new diagnostic metabolite of 3-hydroxy-3-methylglutaryl-coenzyme A lyase deficiency

Deficiency of 3-hydroxy-3-methylglutaryl-coenzyme A (CoA) lyase affects the metabolism of leucine as well as ketogenesis. This disorder is one of an increasing list of inborn errors of metabolism that presents clinically like Reye's Syndrome or nonketotic hypoglycemia. Four patients with proven 3-hydroxy-3-methylglutaryl-CoA lyase deficiency were shown to excrete a new diagnostically specific metabolite. The technique of fast atom bombardment and tandem mass spectrometry revealed that only 3-methylglutaryl-CoA is a substrate for acylcarnitine formation. Neither 3-methylglutaconyl-CoA nor 3-hydroxy-3-methylglutaryl-CoA are excreted as acylcarnitines. The excretion of 3-methylglutarylcarnitine may explain, in part, the apparent secondary carnitine deficiency in this disorder. Carnitine supplementation with moderate dietary restrictions may be a useful treatment strategy for this disorder.

Simultaneous liquid chromatographic determination of glutaric acid, phenylephrine, and benzyl alcohol in a prototype nasal spray with application to di- and tricarboxylic acids

A rapid reversed-phase high-performance liquid chromatographic method for the simultaneous determination of glutaric acid, phenylephrine, and benzyl alcohol in nasal spray has been developed. UV detection was utilized at 210 nm for the assay of glutaric acid and phenylephrine with an adjustment to 254 nm for the measurement of benzyl alcohol. Linearity and recovery data were obtained for each component in spiked placebo studies. An investigation of the retention mechanisms of the three components showed that phenylephrine was retained by ion-pairing with octanesulfonate anion while glutaric acid and benzyl alcohol partitioned as a suppressed ion and a neutral molecule, respectively. The method has been further extended to the reversed-phase separation of di- and tricarboxylic acids using a totally aqueous 0.0074 M phosphoric acid mobile phase. The retention of these acids was related to their octanol-water partition coefficients and structural variation.

Prenatal diagnosis of glutaric aciduria type II by direct chemical analysis of dicarboxylic acids in amniotic fluid

A method for the measurement of dicarboxylic acids in amniotic fluid was developed that utilizes isolation of the acids by liquid partition chromatography and quantification by ammonia chemical ionization selected ion monitoring, gas chromatography-mass spectrometry. The concentrations of dicarboxylic acids in ten normal samples of amniotic fluid (mumol/l +/- 1 S.D.) were glutaric acid 0.91 +/- 0.15, adipic acid 0.33 +/- 0.08, suberic acid 0.27 +/- 0.08, and sebacic acid 0.21 +/- 0.10. A highly elevated concentration of 14.48 mumol/l glutaric acid was found in the amniotic fluid of a pregnancy in which the fetus was affected with glutaric aciduria type II. Adipic, suberic and sebacic acids were also significantly elevated. The dicarboxylic acids were normal in the amniotic fluid of a pregnancy at risk for glutaric aciduria type II in which the fetus was unaffected. This method is suitable for the rapid prenatal diagnosis of glutaric aciduria types I and II and of potential value for the prenatal diagnosis of other inherited disorders in which dicarboxylic acids accumulate.

Antenatal diagnosis of glutaric acidemia

Two pregnancies at risk for glutaric acidemia were monitored. In one, in which the fetus was not affected, glutaric acid was not detected in the amniotic fluid at amniocentesis (15 weeks) and the glutaryl-CoA dehydrogenase activity of cultured amniotic cells was normal. In the other, a marked elevation of glutaric acid in the amniotic fluid, together with deficiency of glutaryl-CoA dehydrogenase in amniotic cells, prompted termination of the pregnancy, and studies on the abortus confirmed the diagnosis of glutaric acidemia. Glutaric acidemia, is, thus, another inborn error of metabolism which can be diagnosed in utero.

alpha-Guanidinoglutaric acid in cobalt-induced epileptogenic cerebral cortex of cats

Guanidino compounds in the cobalt-induced epileptogenic cerebral cortex of cats were fluorometrically analysed by a JASCO G-520 guanidino compounds analyser, and an unknown high peak was observed in the chromatogram that was identical to the peak of authentic alpha-guanidinoglutaric acid. In another experiment, the substance was extracted from the cobalt focus tissue, converted into dimethylpyrimidyl derivative-butylester, and analysed by a GC/MS technique. The mass spectrum of the substance was identical to the dimethylpyrimidyl derivative of alpha-guanidinoglutaric acid butylester (M+ = 365).

Free radicals in dicarboxylic acids: an e.s.r. study of gamma-irradiated single crystals of glutaric acid at 77 K

Electron spin resonance techniques were used to study the gamma-radiation-induced free radicals in single crystals of glutaric acid in the temperature range from 77 K to 300 K. Three different radicals are stabilized at 77 K. The decarboxylation radical is the dominant species and the other two radicals are assigned to the anion and to the substituted acetyl sigma-radical. When the temperature of the crystal is raised, these radicals disappear and the previously studied room temperature radicals appear. E.S.R.-data and the results from semi-empirical INDO-MO calculations were compared in order to elucidate the structures of the various radicals.

Glutaric aciduria: biochemical and morphologic considerations

Biochemical and morphologic studies on a patient with glutaric aciduria are presented. Generalized aminoaciduria, alpha-aminoadipic aciduria, and saccharopinuria were noted just prior to death, as well as glutaconic aciduria greater than beta-hydroxyglutaric aciduria. Mutant liver mitochondria did not oxidize glutaryl-CoA to glutaconyl-CoA, indicating deficiency of glytaryl-CoA dehydrogenase. Autopsy revealed cerebral edema, ischemic neuronal changes, and striatal degeneration in the brain with fatty changes in liver, kidney, and myocardium.

Indirect assessment of hydroxymethylglutaryl-CoA reductase (NADPH) activity in liver tissue

We describe an indirect method for assessing variation in 3-hydroxy-3-methylglutaryl-coenzyme A reductase (NADPH) activity in liver tissue. 3-Hydroxy-3-methyglutaryl-CoA and mevalonate concentrations in the tissue homogenate are estimated in terms of absorbances and the ratio between the two is taken as an index of activity of the enzyme, which catalyzes the conversion of 3-hydroxy-3-methylglutaryl-CoZ to mevalonate. The ratio increases under conditions in which activity of this enzyme in liver reportedly decreases (e.g., fasting, cholesterol feeding) and decreases under conditions in which the activity of this enzyme reportedly increases (e.g., Triton injection, phenobarbital treatment). We assessed the magnitude of hepatic cholesterogenesis in intact male albino rats by using [1,2-14C] acetate, in fed controls, fasted, cholesterol-fed, Triton-treated, and phenobarbital-treated. The ratio, 3-hydroxy-3-methylglutaryl-CoA/mevalonate was estimated in liver tissue for all the above groups. The method is simple, reproducible, and does not require any unusual chemicals.

[Paraplacental feeding of the fetus]

Amino acids, intraamnially administered, disappear unexpectedly rapidly and relatively uniformly from the amniotic fluid. During a placental insufficiency and thus a simultaneously present intrauterine protein deficiency, the amino acid level in the amniotic fluid decreases especially rapidly whereas it remains practically unchanged for hours following death in utero. This observation suggests that the infused amino acids are utilized by the living fetus. This is supported by a decrease in the glucose concentration and an increase in the pyruvate of the amniotic fluid. According to the experiences obtained until now it seems reasonable to supply the fetus with vital substrates via the paraplacental route.

Biogenesis of zearalenone (F-2) by Fusarium roseum 'Graminearum'

The biogenesis of zearalenone or F-2 (2,4-dihydroxy-6-(10-hydroxy-6-oxo-trans-1-undecenyl) benzoic acid lactone) was examined. Of several possible precursors, acetate and malonate were incorporated most readily, and malonate was shown to inhibit incorporation from acetate. Zearalenone isolated from cultures of Fusarium roseum fed 1-14C-acetate was chemically degraded and the distribution of 14C examined. Both the kinetic and degradation studies suggest that zearalenone is derived from acetate through the polyketide pathway.

Short-chain acids of Pseudomonas species encountered in clinical specimens

The short-chain acids of 36 strains of Pseudomonas grown on Trypticase soy agar were determined by gas-liquid chromatography. Distinct acid profiles were observed for each of the eight species tested. Propionic, isobutyric, and isovaleric acids were the principal acids detected in media extracts of P. maltophilia, P. cepacia, P. pseudoalcaligenes, P. diminuta, and P. vesiculare. The presence and relative amounts of the isobutyric and isovaleric acids clearly distinguished P. maltophilia, P. pseudoalcaligenes, and P. cepacia from other species. P. diminuta could be distinguished from P. vesiculare by the production of glutaric acid; P. testosteroni was the only species tested which produced relatively large amounts of phenylacetic acid.