Liquid chromatographic-atmospheric pressure chemical ionization mass spectrometric analysis of glycine conjugates and urinary isovalerylglycine in isovaleric acidemia

Ultraperformance Liquid Chromatography Coupled with Quadrupole Time-of-Flight Mass Spectrometry-Based Metabolomics and Lipidomics Identify Biomarkers for Efficacy Evaluation of Mesalazine in a Dextran Sulfate Sodium-Induced Ulcerative Colitis Mouse Model

This study aims to identify biomarkers for evaluating the therapeutic efficacy of mesalazine on ulcerative colitis by metabolomics and lipidomics. A dextran sulfate sodium-induced mouse model was used. The disease status was assessed by a disease activity index, the TNF-α level of colon was measured by an enzyme-linked immunosorbent assay, and the pathological changes of colon tissue was examined by hematoxylin-eosin staining. Serum metabolomics and lipidomics analysis based on ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry were applied to decipher the metabolic profile changes. Multivariate analysis was applied to differentiate the metabolites of controls, models, and mesalazine-treated mice. By the receiver operating characteristic (ROC) analysis, 40 differential metabolites with an area under curve (AUC) >0.80 were screened out between control and model groups. Among them, four potential biomarkers (palmitoyl glucuronide, isobutyrylglycine, PC (20:3 (5Z, 8Z, 11Z)/15:0) and L-arginine) had a signficantly reversed level of peak areas in the mesalazine group, and three of them were closely correlated with mesalazine efficacy by linear regression analysis. Furthermore, metabolic pathway analysis revealed several dysregulated pathways in colitis mice, including glycerophospholipid metabolism, pyrimidine metabolism, linoleic acid metabolism, arginine biosynthesis, etc. This study indicates that serum metabolomics is a useful approach that can noninvasively evaluate the therapeutic effect and provide unique insights into the underlying mechanism of mesalazine.

Hyperammonaemia in classic organic acidaemias: a review of the literature and two case histories

Background

The ‘classic’ organic acidaemias (OAs) (propionic, methylmalonic and isovaleric) typically present in neonates or infants as acute metabolic decompensation with encephalopathy. This is frequently accompanied by severe hyperammonaemia and constitutes a metabolic emergency, as increased ammonia levels and accumulating toxic metabolites are associated with life-threatening neurological complications. Repeated and frequent episodes of hyperammonaemia (alongside metabolic decompensations) can result in impaired growth and intellectual disability, the severity of which increase with longer duration of hyperammonaemia. Due to the urgency required, diagnostic evaluation and initial management of patients with suspected OAs should proceed simultaneously. Paediatricians, who do not have specialist knowledge of metabolic disorders, have the challenging task of facilitating a timely diagnosis and treatment. This article outlines how the underlying pathophysiology and biochemistry of the organic acidaemias are closely linked to their clinical presentation and management, and provides practical advice for decision-making during early, acute hyperammonaemia and metabolic decompensation in neonates and infants with organic acidaemias.

Clinical management

The acute management of hyperammonaemia in organic acidaemias requires administration of intravenous calories as glucose and lipids to promote anabolism, carnitine to promote urinary excretion of urinary organic acid esters, and correction of metabolic acidosis with the substitution of bicarbonate for chloride in intravenous fluids. It may also include the administration of ammonia scavengers such as sodium benzoate or sodium phenylbutyrate. Treatment with N-carbamyl-L-glutamate can rapidly normalise ammonia levels by stimulating the first step of the urea cycle.

Conclusions

Our understanding of optimal treatment strategies for organic acidaemias is still evolving. Timely diagnosis is essential and best achieved by the early identification of hyperammonaemia and metabolic acidosis. Correcting metabolic imbalance and hyperammonaemia are critical to prevent brain damage in affected patients.

Dietary practices in isovaleric acidemia: A European survey

Background

In Europe, dietary management of isovaleric acidemia (IVA) may vary widely. There is limited collective information about dietetic management.

Aim

To describe European practice regarding the dietary management of IVA, prior to the availability of the E-IMD IVA guidelines (E-IMD 2014).

Methods

A cross-sectional questionnaire was sent to all European dietitians who were either members of the Society for the Study of Inborn Errors of Metabolism Dietitians Group (SSIEM-DG) or whom had responded to previous questionnaires on dietetic practice (n = 53). The questionnaire comprised 27 questions about the dietary management of IVA.

Results

Information on 140 patients with IVA from 39 centres was reported. 133 patients (38 centres) were given a protein restricted diet. Leucine-free amino acid supplements (LFAA) were routinely used to supplement protein intake in 58% of centres. The median total protein intake prescribed achieved the WHO/FAO/UNU [2007] safe levels of protein intake in all age groups. Centres that prescribed LFAA had lower natural protein intakes in most age groups except 1 to 10 y. In contrast, when centres were not using LFAA, the median natural protein intake met WHO/FAO/UNU [2007] safe levels of protein intake in all age groups. Enteral tube feeding was rarely prescribed.

Conclusions

This survey demonstrates wide differences in dietary practice in the management of IVA across European centres. It provides unique dietary data collectively representing European practices in IVA which can be used as a foundation to compare dietary management changes as a consequence of the first E-IMD IVA guidelines availability.

Integration of ¹H NMR and UPLC-Q-TOF/MS for a comprehensive urinary metabonomics study on a rat model of depression induced by chronic unpredictable mild stress

Depression is a type of complex psychiatric disorder with long-term, recurrent bouts, and its etiology remains largely unknown. Here, an integrated approach utilizing ¹H NMR and UPLC-Q-TOF/MS together was firstly used for a comprehensive urinary metabonomics study on chronic unpredictable mild stress (CUMS) treated rats. More than twenty-nine metabolic pathways were disturbed after CUMS treatment and thirty-six potential biomarkers were identified by using two complementary analytical technologies. Among the identified biomarkers, nineteen (10, 11,16, 17, 21–25, and 27–36) were firstly reported as potential biomarkers of CUMS-induced depression. Obviously, this paper presented a comprehensive map of the metabolic pathways perturbed by CUMS and expanded on the multitude of potential biomarkers that have been previously reported in the CUMS model. Four metabolic pathways, including valine, leucine and isoleucine biosynthesis; phenylalanine, tyrosine and tryptophan biosynthesis; tryptophan metabolism; synthesis and degradation of ketone bodies had the deepest influence in the pathophysiologic process of depression. Fifteen potential biomarkers (1–2, 4–6, 15, 18, 20–23, 27, 32, 35–36) involved in the above four metabolic pathways might become the screening criteria in clinical diagnosis and predict the development of depression. Moreover, the results of Western blot analysis of aromatic L-amino acid decarboxylase (DDC) and indoleamine 2, 3-dioxygenase (IDO) in the hippocampus of CUMS-treated rats indicated that depletion of 5-HT and tryptophan, production of 5-MT and altered expression of DDC and IDO together played a key role in the initiation and progression of depression. In addition, none of the potential biomarkers were detected by NMR and LC-MS simultaneously which indicated the complementary of the two kinds of detection technologies. Therefore, the integration of ¹H NMR and UPLC-Q-TOF/MS in metabonomics study provided an approach to identify the comprehensive potential depression-related biomarkers and helpful in further understanding the underlying molecular mechanisms of depression through the disturbance of metabolic pathways.

Biosynthesis, degradation and pharmacological importance of the fatty acid amides

The identification of two biologically active fatty acid amides, N-arachidonoylethanolamine (anandamide) and oleamide, has generated a great deal of excitement and stimulated considerable research. However, anandamide and oleamide are merely the best-known and best-understood members of a much larger family of biologically occurring fatty acid amides. In this review, we will outline which fatty acid amides have been isolated from mammalian sources, detail what is known about how these molecules are made and degraded in vivo, and highlight their potential for the development of novel therapeutics.

A sensitive liquid chromatographic method for the analysis of isovaleric and valeric acids in urine as fluorescent derivatives

A simple and sensitive isocratic liquid chromatographic method was developed for the analysis of isovaleric and valeric acids in human urine as biomarkers in metabolic acidosis. The method is based on the derivatization of isovaleric and valeric acids with a fluorescent reagent 2-(2-naphthoxy)ethyl-2-(piperidino)ethanesulfonate for labeling the analytes with the naphthoxy fluorophore. The resulting fluorescent derivatives of isovaleric and valeric acids were separated on a phenyl-hexyl column, using a mixed solvent of methanol-water-tetrahydrofuran (55:31:14, v/v) as the mobile phase. The separated derivatives were monitored with a fluorimetric detector (excitation at 225 nm and emission at 360 nm). The linear range of the method for the determination of isovaleric acid or valeric acid derivative was over 0.2 approximately 8.0 microM. The detection limit (signal to noise ratio=3 with 10 microl injected) of isovaleric acid or valeric acid was about 0.04 microM. Application of the method to the analysis of isovaleric acid in the urine of a patient with isovaleric acidemia proved feasible.

Liquid chromatography-mass spectrometry in forensic and clinical toxicology

This paper reviews liquid chromatographic-mass spectrometric (LC-MS) procedures for the identification and/or quantification of drugs of abuse, therapeutic drugs, poisons and/or their metabolites in biosamples (whole blood, plasma, serum, urine, cerebrospinal fluid, vitreous humor, liver or hair) of humans or animals (cattle, dog, horse, mouse, pig or rat). Papers published from 1995 to early 1997, which are relevant to clinical toxicology, forensic toxicology, doping control or drug metabolism and pharmacokinetics, were taken into consideration. They cover the following analytes: amphetamines, cocaine, lysergide (LSD), opiates, anabolics, antihypertensives, benzodiazepines, cardiac glycosides, corticosteroids, immunosuppressants, neuroleptics, non-steroidal anti-inflammatory drugs (NSAID), opioids, quaternary amines, xanthins, biogenic poisons such as aconitines, aflatoxins, amanitins and nicotine, and pesticides. LC-MS interface types, mass spectral detection modes, sample preparation procedures and chromatographic systems applied in the reviewed papers are discussed. Basic information about the biosample assayed, work-up, LC column, mobile phase, interface type, mass spectral detection mode, and validation data of each procedure is summarized in tables. Examples of typical LC-MS applications are presented.