Suberylglycine

Suberylglycine excretion in the urine from a patient with dicarboxylic aciduria

Suberylglycine (HOOC(CH2)6CONHCH2COOH) was found in the urine from a patient with C6-C10-omega-dicarboxylic aciduria and unexplained episodes of lethargy and unconsciousness. The total excretion of adipic, suberic and sebacic acid ranged from 0.77 to 1.3 mg/mg creatinine after episodes of acute attack of the disease. Suberylglycine, identified by gas chromatography/mass spectrometry, was repeatedly found in the urine samples. The amount of this conjugate ranged from 0.2 to 0.5 mg/mg creatinine. The precursors of the dicarboxylic acids are suggested to be long chain monocarboxylic acids, oxidized through omega- and beta-oxidation to adipic, suberic and sebacic acid. Suberylglycine is subsequently formed by glycine-N-acylase catalyzed conjugation.

Stable isotope dilution analysis of n-hexanoylglycine, 3-phenylpropionylglycine and suberylglycine in human urine using chemical ionization gas chromatography/mass spectrometry selected ion monitoring

We describe a gas chromatographic/mass spectrometric method for the accurate determination of n-hexanoylglycine, 3-phenylpropionylglycine and suberylglycine in urine for the diagnosis of hereditary medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. These acylglycines had previously been detected in urine from patients with MCAD deficiency, but their diagnostic values were unknown because of a lack of appropriate analytical methods. n-Hexanoyl(1,2-13C)glycine, 3-phenylpropionyl(2-13C,15N)glycine and suberyl(2-13C,15N)glycine were synthesized and used as internal standards. Ammonia chemical ionization was utilized to generate intense [M + H]+ ions for selected-ion monitoring quantification. The whole procedure is fast and can be performed by a low-resolution gas chromatographic/mass spectrometric system, giving accurate results over a range of three orders of magnitude (0.0167-16.7 micrograms/ml). The results from the analyses of 54 urine samples from 21 MCAD-deficient patients and various control samples using this method established that n-hexanoyglycine and 3-phenylpropionylglycine were highly diagnostic for this disease, while suberylglycine was found less specific.

Gas chromatography--mass spectrometry (GC--MS) diagnosis of two cases of medium chain acyl-CoA dehydrogenase deficiency

Two patients with hypoketotic hypoglycaemia and dicarboxylic aciduria are described. Studies of their urinary organic acids by gas chromatography-mass spectrometry (GC-MS) showed an excretion of dicarboxylic acids (adipic suberic and sebacic acids), unsaturated dicarboxylic acids (cis-octenedioic and decenedioic acids),5-hydroxyhexanoic acid, hexanoyl-glycine and suberylglycine. Deficiency of the medium chain acyl-CoA dehydrogenase (MCAD) in fibroblasts was documented for both children. Despite a similar presentation (hypoglycaemic coma), organic acid profile (dicarboxylic aciduria and suberylglycine excretion) and enzyme deficiency (MCAD), they did not respond similarly to glucose infusion.

Identification of Novel Biomarkers for Acute Radiation Injury Using Multiomics Approach and Nonhuman Primate Model

Purpose: The availability of validated biomarkers to assess radiation exposure and to assist in developing medical countermeasures remains an unmet need.
Methods and materials: We used a cobalt-60 γ-irradiated nonhuman primate (NHP) model to delineate a multiomics-based serum probability index of radiation exposure. Both male and female NHPs were irradiated with different doses ranging from 6.0 to 8.5 Gy, with 0.5 Gy increments between doses. We leveraged high-resolution mass spectrometry for analysis of metabolites, lipids, and proteins at 1, 2, and 6 days postirradiation in NHP serum.
Results: A logistic regression model was implemented to develop a 4-analyte panel to stratify irradiated NHPs from unirradiated with high accuracy that was agnostic for all doses of γ-rays tested in the study, up to 6 days after exposure. This panel was comprised of Serpin family A9, acetylcarnitine, glycerophosphocholine (16:0/22:6), and suberylglycine, which showed 2- to 4-fold elevation in serum abundance upon irradiation in NHPs and can potentially be translated as a molecular diagnostic for human use after larger validation studies.
Conclusions: Taken together, this study, for the first time, demonstrates the utility of a combinatorial molecular characterization approach using an NHP model for developing minimally invasive assays from small volumes of blood that can be effectively used for radiation exposure assessments.

Medium-chain acyl-CoA dehydrogenase deficiency. Diagnosis by stable-isotope dilution measurement of urinary n-hexanoylglycine and 3-phenylpropionylglycine

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, one of the most common inherited metabolic disorders, is often mistaken for the sudden infant death syndrome or Reye's syndrome. Diagnosing it has been difficult because of a lack of fast and reliable diagnostic methods. We developed a stable-isotope dilution method to measure urinary n-hexanoylglycine, 3-phenylpropionylglycine, and suberylglycine, and we retrospectively tested its accuracy in diagnosing MCAD deficiency. We measured the concentrations of these three acylglycines in 54 urine samples from 21 patients with confirmed MCAD deficiency during the acute and asymptomatic phases of the illness and compared the results with the concentrations in 98 samples from healthy controls and patient controls with various diseases. The levels of urinary hexanoylglycine and phenylpropionylglycine were significantly increased in all samples from the patients with MCAD deficiency, clearly distinguishing them from both groups of controls. Although urinary suberylglycine was increased in the patients, the range of values in the normal controls who were receiving formula containing medium-chain triglycerides was very wide, overlapping somewhat with the values in the patients with asymptomatic MCAD deficiency. These results indicate that the measurement of urinary hexanoylglycine and phenylpropionylglycine by our method is highly specific for the diagnosis of MCAD deficiency. The method is fast and can be applied to random urine specimens, without any pretreatment of patients.