Mitochondrial involvement and erythronic acid as a novel biomarker in transaldolase deficiency.

BACKGROUND: Sedoheptulose, arabitol, ribitol, and erythritol have been identified as key diagnostic metabolites in TALDO deficiency. METHOD: Urine from 6 TALDO-deficient patients and TALDO-deficient knock-out mice were analyzed using ¹H-NMR spectroscopy and GC-mass spectrometry. RESULTS: Our data confirm the known metabolic characteristics in TALDO-deficient patients. The ß-furanose form was the major sedoheptulose anomer in TALDO-deficient patients. Erythronic acid was identified as a major abnormal metabolite in all patients and in knock-out TALDO mice implicating an as yet unknown biochemical pathway in this disease. A putative sequence of enzymatic reactions leading to the formation of erythronic acid is presented. The urinary concentration of the citric acid cycle intermediates 2-oxoglutaric acid and fumaric acid was increased in the majority of TALDO-deficient patients but not in the knock-out mice. CONCLUSION: Erythronic acid is a novel and major hallmark in TALDO deficiency. The pathway leading to its production may play a role in healthy humans as well. In TALDO-deficient patients, there is an increased flux through this pathway. The finding of increased citric acid cycle intermediates hints toward a disturbed mitochondrial metabolism in TALDO deficiency.

Urinary chemical fingerprint left behind by repeated NSAID administration: Discovery of putative biomarkers using artificial intelligence.

Prediction and early detection of kidney damage induced by nonsteroidal anti-inflammatories (NSAIDs) would provide the best chances of maximizing the anti-inflammatory effects while minimizing the risk of kidney damage. Unfortunately, biomarkers for detecting NSAID-induced kidney damage in cats remain to be discovered. To identify potential urinary biomarkers for monitoring NSAID-based treatments, we applied an untargeted metabolomics approach to urine collected from cats treated repeatedly with meloxicam or saline for up to 17 days. Applying multivariate analysis, this study identified a panel of seven metabolites that discriminate meloxicam treated from saline treated cats. Combining artificial intelligence machine learning algorithms and an independent testing urinary metabolome data set from cats with meloxicam-induced kidney damage, a panel of metabolites was identified and validated. The panel of metabolites including tryptophan, tyrosine, taurine, threonic acid, pseudouridine, xylitol and lyxitol, successfully distinguish meloxicam-treated and saline-treated cats with up to 75-100% sensitivity and specificity. This panel of urinary metabolites may prove a useful and non-invasive diagnostic tool for monitoring potential NSAID induced kidney injury in feline patients and may act as the framework for identifying urine biomarkers of NSAID induced injury in other species.

Excretion of metabolites of the synthetic cannabinoid JWH-018 in urine after controlled inhalation.

Each year, synthetic cannabinoids are occurring in high numbers on the illicit drug market but data obtained after controlled application are rare. The present study on pharmacokinetics in urine is part of a pilot study on adverse effects of JWH-018, which is one of the oldest and best known synthetic cannabinoids. Six subjects inhaled smoke from 2 and 3mg JWH-018. The drug and ten potential metabolites were analyzed in urine samples collected during 12h after inhalation by liquid chromatography-mass spectrometry (LC-MS/MS) without and with conjugate cleavage. The parent compound was not detectable, but 13 of its metabolites, all of which were conjugated. Concentrations of the predominant metabolite, JWH-018 pentanoic acid, were less than 5ng/ml, but in two subjects it was still detected up to 4 weeks after ingestion. Other major metabolites were 5- and 4-HOpentyl-JWH-018, JWH-073 butanoic acid and a hypothetically dihydroxylated and dehydrogenated metabolite of JWH-018. Occasionally, further hydroxylated metabolites were found. Generally, hydroxylated metabolites were detected in concentrations lower than 1ng/ml already 10h after inhalation. All concentrations were much lower than reported for urine samples of authentic JWH-018 users. The formation of the metabolite JWH-018 pentanoic acid was found to be slightly delayed, but its rather high concentrations and detection over several weeks after single dosing makes it a useful target for urine analysis. The different excretion of carboxylic acid and hydroxylated metabolites may aid in evaluation of time of use.

Short-chain acyl-coenzyme A dehydrogenase deficiency. Clinical and biochemical studies in two patients.

We describe two patients with short-chain acyl-coenzyme A (CoA) dehydrogenase (SCADH) deficiency. Neonate I excreted large amounts of ethylmalonate and methylsuccinate; ethylmalonate excretion increased after a medium-chain triglyceride load. Neonate II died postnatally and excreted ethylmalonate, butyrate, 3-hydroxybutyrate, adipate, and lactate. Both neonates' fibroblasts catabolized [1-14C]butyrate poorly (29-64% of control). Neonate I had moderately decreased [1-14C]octanoate catabolism (43-60% of control), while neonate II oxidized this substrate normally; both catabolized radiolabeled palmitate, succinate, and/or leucine normally. Cell sonicates from neonates I and II dehydrogenated [2,3-3H]butyryl-CoA poorly (41 and 53% of control) and [2,3-3H]octanoyl-CoA more effectively (59 and 95% of control). Mitochondrial acyl-CoA dehydrogenase (ADH) activities with butyryl- and octanoyl-CoAs were 37 and 56% of control in neonate I, and 47 and 81% of control in neonate II, respectively. Monospecific medium-chain ADH (MCADH) antisera inhibited MCADH activity towards both butyryl- and octanoyl-CoAs, revealing SCADH activities to be 1 and 11% of control for neonates I and II, respectively. Fibroblast SCADH and MCADH activities were normal in an adult female with muscular SCADH deficiency.

Metabolic effects of exogenous glucocorticoids in fasted man.

The influence of administering excessive amounts of glucocorticoids on circulating substrates and hormones and on urinary excretion of nitrogenous compounds and ketone bodies was examined in man after prolonged starvation. After 35 days of total caloric deprivation the administration of high physiologic doses of glucocorticoids increased circulating glucose and insulin levels without intensifying total urinary nitrogen excretion. The increased blood glucose seemed to be due to diminished peripheral uptake rather than augmented gluconeogenesis. A small, transient increase in circulating plasma amino acids was observed. However, the secondary rise in serum insulin seemed to block the proteolytic effect(s) of glucocorticoids, preventing them from mobilizing body protein stores during starvation. There was no change in circulating free fatty acids or glycerol. Thus, it appeared that the potential catabolic action of excessive glucocorticoids was offset by the anabolic effect of insulin, and a new state of homeostasis was established.An additional effect of glucocorticoid administration was a marked diminution of renal excretion of ketone bodies.

Determination of L-threonate in human plasma and urine by high performance liquid chromatography-tandem mass spectrometry.

A fast and selective HPLC-MS-MS method was established to determine L-threonate in human plasma and urine. Plasma and urine samples were extracted by protein precipitation and diluted with water, then chromatographed on an YMC J'Sphere C(18) column with methanol-acetonitrile-10mM ammonium acetate (20:5:75, v/v) as mobile phase, and at a flow rate of 0.2 ml/min. Detection was performed on a triple-quadrupole tandem mass spectrometer using negative electrospray ionization (ESI). Multiple reactions monitoring (MRM) was used and L-threonate was quantified by monitoring the ion transition of m/z 134.5-->74.7. The linear calibration curves of L-threonate in plasma and urine were obtained over the concentration range of 0.25-50 microg/ml and 2.5-500 microg/ml, respectively. Lower limit of quantitation was 0.25 and 2.5 microg/ml, respectively. Accuracy was within 85-115%, and intra- and inter-batch precision (R.S.D.%) were within +/-15%. The method proved to be accurate and specific, and was applied to the pharmacokinetic study of L-threonate in Chinese healthy subjects.

Interstitial Cystitis-Associated Urinary Metabolites Identified by Mass-Spectrometry Based Metabolomics Analysis.

This study on interstitial cystitis (IC) aims to identify a unique urine metabolomic profile associated with IC, which can be defined as an unpleasant sensation including pain and discomfort related to the urinary bladder, without infection or other identifiable causes. Although the burden of IC on the American public is immense in both human and financial terms, there is no clear diagnostic test for IC, but rather it is a disease of exclusion. Very little is known about the clinically useful urinary biomarkers of IC, which are desperately needed. Untargeted comprehensive metabolomic profiling was performed using gas-chromatography/mass-spectrometry to compare urine specimens of IC patients or health donors. The study profiled 200 known and 290 unknown metabolites. The majority of the thirty significantly changed metabolites before false discovery rate correction were unknown compounds. Partial least square discriminant analysis clearly separated IC patients from controls. The high number of unknown compounds hinders useful biological interpretation of such predictive models. Given that urine analyses have great potential to be adapted in clinical practice, research has to be focused on the identification of unknown compounds to uncover important clues about underlying disease mechanisms.

The scent of age.

In many species, older males are often preferred mates because they carry 'good' genes that account for their viability. How females discern a male's age is a matter of question. However, for animals that rely heavily on chemical communication there is some indication that an animal's age can be determined by its scent. To investigate whether there are changes in body odours with age, and if so their composition, mice were trained in a Y-maze to discriminate urine odours of donor mice of different ages: Adult (3-10 months old) and Aged (more than 17 months old). Trained mice could discriminate between these two age groups by odour alone. To determine the chemical basis for these discriminations, studies were performed using gas chromatography and mass spectrometry. These analyses demonstrated differences in the ratio of urinary volatiles with age. The most prominent differences involved significantly greater amounts of 2-phenylacetamide and significantly lower amounts of methylbutyric acids in Aged animals relative to Adult animals. Fractionating and manipulating the levels of these compounds in the urine demonstrated that the mice can distinguish age based on variation in amounts of these specific compounds in the combined urine.

[Determination of urinary alpha-keto-gamma-methylthiobutyric acid in hypermethionemia by use of gas chromatography and flame photometry (author's transl)]. / Dosage par chromatographie gazeuse avec détection en photometrie de flamme de l'acide alpha-céto-gamma-méthylthiobutyrique urinaire dans les hyperméthioninémies.

In this paper we describe the determination of urinary alpha-keto-gamma-methylthiobutyric acid (ACMTB) by the use of gas chromatography of its quinoxalinol derivative and specific detection of sulphur with a flame photometric detector. Using these techniques, it was possible to study the urinary elimination of this secondary metabolite of methionine in normal children, homocystinurics and in one case of hypermethioninemia. The excretion of ACMTB is normally very weak and is strongly increased when the principal pathway of methionine is blocked.

Excretion of short-chain N-acylglycines in the urine of a patient with D-glyceric acidemia.

Five urine samples were collected in clinically quiet periods over a period of one year from a patient suffering from D-glyceric acidemia, and investigated for presence or absence of glycine-conjugates. The findings of isovalerylglycine, 2-methylbutyrylglycine, isobutyrylglycine, and tiglylglycine are interpreted as indications of intracelluar accumulations of isovaleryl-CoA, 2-methylbutyryl-CoA and isobutyryl-CoA. Similarly, the findings of elevated amounts of butyric acid and hexanoic acid together with butyrylglycine, hexanoylglycine, and suberic acid suggest intracellular accumulations of straight-chain acyl-CoA's. It is therefore suggested that this child has a common derangement in his acyl-CoA dehydrogenase (in addition to his primary defect). As possible secondary consequences of this, two points can be mentioned: firstly hyperglycinemia, from which the patient suffered, and secondly, diminished tendency to ketosis, a condition from which the child never suffered, not even in connection with severe intercurrent disease.

A combined defect of three mitochondrial carboxylases presenting as biotin-responsive 3-methylcrotonyl glycinuria and 3-hydroxyisovaleric aciduria.

A child with a history of episodes of metabolic acidosis was found to excrete 3-hydroxyisovaleric acid and 3-methylcrotonylglycine. These metabolites disappeared following the administration of biotin. The specific activities of propionyl CoA carboxylase, 3-methylcrotonyl CoA carboxylase and pyruvate carboxylase were found to be low in skin fibroblasts cultured in the absence of added biotin. With the addition of biotin, the specific activity of all three carboxylases returned to normal, that of 3-methylcrotonyl CoA carboxylase ahowing the greatest sensitivity to biotin.