Determination of succinylacetone in dried blood spots and liquid urine as a dansylhydrazone by liquid chromatography tandem mass spectrometry

Emerging trends and applications of metabolomics in food science and nutrition

The study of all chemical processes involving metabolites is known as metabolomics. It has been developed into an essential tool in several disciplines, such as the study of plant physiology, drug development, human diseases, and nutrition. The field of food science, diagnostic biomarker research, etiological analysis in the field of medical therapy, and raw material quality, processing, and safety have all benefited from the use of metabolomics recently. Food metabolomics includes the use of metabolomics in food production, processing, and human diets. As a result of changing consumer habits and the rising of food industries all over the world, there is a remarkable increase in interest in food quality and safety. It requires the employment of various technologies for the food supply chain, processing of food, and even plant breeding. This can be achieved by understanding the metabolome of food, including its biochemistry and composition. Additionally, Food metabolomics can be used to determine the similarities and differences across crop kinds, as an indicator for tracking the process of ripening to increase crops' shelf life and attractiveness, and identifying metabolites linked to pathways responsible for postharvest disorders. Moreover, nutritional metabolomics is used to investigate the connection between diet and human health through detection of certain biomarkers. This review assessed and compiled literature on food metabolomics research with an emphasis on metabolite extraction, detection, and data processing as well as its applications to the study of food nutrition, food-based illness, and phytochemical analysis. Several studies have been published on the applications of metabolomics in food but further research concerning the use of standard reproducible procedures must be done. The results published showed promising uses in the food industry in many areas such as food production, processing, and human diets. Finally, metabolome-wide association studies (MWASs) could also be a useful predictor to detect the connection between certain diseases and low molecular weight biomarkers.

Clinical experience with hepatorenal tyrosinemia from a single Egyptian center

Although very recently, in Egypt, sick newborn screening has included screening for hepatorenal tyrosinemia, yet, it is not yet included in nationwide neonatal screening and hence diagnosis may be delayed. The aim of this study was to analyze data of all cases presenting with hepatorenal tyrosinemia to the Pediatric Hepatology Unit, Cairo University, Egypt from 2006 to 2019. Data were retrieved from patients’ files including age of onset of symptoms, clinical signs, blood counts, liver functions, serum phosphorous, alpha-fetoprotein, succinylacetone and abdominal ultrasound. During this period, 76 patients were diagnosed with hepatorenal tyrosinemia if succinylacetone in dry blood spot was elevated above 1 μmol/L. These 76 cases came from 70 families; consanguinity was reported in 61 families. In our cohort we reported 30 affected siblings with a similar clinical presentation, who died undiagnosed. Presentation was acute in 26%, subacute in 30% and chronic in 43%. Abdominal distention was the commonest presenting symptom (52.6%). Coagulopathy was the commonest derangement in liver functions; hyperbilirubinemia and raised transaminases were less common. Ultrasound findings included hepatic focal lesions in 47% and enlarged echogenic kidneys in 39% and 45.3% respectively. Only 20 children were treated with Nitisinone because of unavailability and high costs; seven out of them underwent liver transplantation. In conclusion, although hepatorenal tyrosinemia is a rare inborn error of metabolism, in a large population country with high rate of consanguinity; this disease is not uncommonly diagnosed. The current treatment is not readily available because of the costs in a resource-limited country. Neonatal screening and subsidization of the costly medication need to be considered.

The use of mass spectrometry to analyze dried blood spots

Dried blood spots (DBS) typically consist in the deposition of small volumes of capillary blood onto dedicated paper cards. Comparatively to whole blood or plasma samples, their benefits rely in the fact that sample collection is easier and that logistic aspects related to sample storage and shipment can be relatively limited, respectively, without the need of a refrigerator or dry ice. Originally, this approach has been developed in the sixties to support the analysis of phenylalanine for the detection of phenylketonuria in newborns using bacterial inhibition test. In the nineties tandem mass spectrometry was established as the detection technique for phenylalanine and tyrosine. DBS became rapidly recognized for their clinical value: they were widely implemented in pediatric settings with mass spectrometric detection, and were closely associated to the debut of newborn screening (NBS) programs, as a part of public health policies. Since then, sample collection on paper cards has been explored with various analytical techniques in other areas more or less successfully regarding large-scale applications. Moreover, in the last 5 years a regain of interest for DBS was observed and originated from the bioanalytical community to support drug development (e.g., PK studies) or therapeutic drug monitoring mainly. Those recent applications were essentially driven by improved sensitivity of triple quadrupole mass spectrometers. This review presents an overall view of all instrumental and methodological developments for DBS analysis with mass spectrometric detection, with and without separation techniques. A general introduction to DBS will describe their advantages and historical aspects of their emergence. A second section will focus on blood collection, with a strong emphasis on specific parameters that can impact quantitative analysis, including chromatographic effects, hematocrit effects, blood effects, and analyte stability. A third part of the review is dedicated to sample preparation and will consider off-line and on-line extractions; in particular, instrumental designs that have been developed so far for DBS extraction will be detailed. Flow injection analysis and applications will be discussed in section IV. The application of surface analysis mass spectrometry (DESI, paper spray, DART, APTDCI, MALDI, LDTD-APCI, and ICP) to DBS is described in section V, while applications based on separation techniques (e.g., liquid or gas chromatography) are presented in section VI. To conclude this review, the current status of DBS analysis is summarized, and future perspectives are provided.

Evaluation of factors influencing accuracy in the analysis of succinylacetone in dried blood spots

BACKGROUND

Dried blood spots offer specific advantages over conventional blood collection methods, but with certain limitations. This article aims to evaluate factors which affect succinylacetone test in dried blood spots.

METHODS

Whole blood with defined hematocrit and blood volume spiked with succinylacetone was spotted on filter paper, and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Four hematocrit levels (30%, 40%, 50%, and 60%) and five blood volume levels (10, 30, 50, 70, and 100 μl) were tested.

RESULTS

Succinylacetone concentration increased with increasing hematocrit, large bias from added concentration was found to be - 45% when hematocrit was 30%, as the difference of hematocrit level between the calibrator and QC sample increased, the bias from nominal value was increased. Blood volume also has effect on succinylacetone concentration level, but the accuracy was <15% when blood volume was 10 to 50 μl, and >20% as the blood volume went to ≥70 μl.

CONCLUSIONS

Both hematocrit and blood volume have effect on analysis of succinylacetone in dried blood spots, the effect of hematocrit is more significant, due to hematocrit level of majority Type I tyrosinemia patients is low, diagnoses may be missed by using dried blood spots to analysis.

Hereditary tyrosinemia type 1 from a single center in Egypt: clinical study of 22 cases

BACKGROUND

Hereditary tyrosinemia type 1 (HT1) is an increasingly recognized inborn error of metabolism among Egyptian children. This study was undertaken to define the presenting clinical, biochemical and imaging features and outcome of 2-(2-motrp-4-trifluoromethylbenzoyl)-1, 3-cyclohexanedione (NTBC) therapy and liver transplantation in a cohort of Egyptian children diagnosed with HT1.

METHODS

The study was carried out at the Pediatric Hepatology Unit at Cairo University Children's Hospital. HT1 was diagnosed by quantification of succinylacetone (SA) in dry blood spots.

RESULTS

Twenty-two patients were diagnosed with HT1 in a period of 3 years from August 2006 to July 2009. Infants with focal hepatic lesions and hepatomegaly (n=13) were younger at diagnosis than those with rickets (n=5) (median age: 3.25 vs. 10 months; P=0.05). Alpha fetoprotein was highly elevated in all children. Seven children died within a few weeks of diagnosis before therapy was initiated. Ten children were treated with NTBC. The response to NTBC treatment was apparent by a steep drop in serum alpha fetoprotein (AFP) and undetectable SA in urine within 2 months. Three children underwent living donor liver transplantation after treatment with NTBC for 10, 18 and 22 months respectively, despite adequate response to therapy because of financial issues. The explanted livers were all cirrhotic with no dysplasia or malignant transformation.

CONCLUSIONS

Focal hepatic lesions are the commonest presentation of HT1 patients and they present at an earlier age than rickets. NTBC is effective but very expensive. Liver transplantation is still considered in HT1 patients.

Monitoring tyrosinaemia type I: Blood spot test for nitisinone (NTBC)

BACKGROUND

Quantification of nitisinone, 2-(nitro-4-trifluoromethylbenzoyl)1,3-cyclohexanedione (NTBC) has been repeatedly described. Nevertheless monitoring of NTBC has not yet become part of routine therapy surveillance in tyrosinaemia type I (OMIM 276700). We developed a blood spot test to facilitate collection and transport of samples. Furthermore, the test material can be used for determination of other parameters like tyrosine and succinylacetone.

METHOD

For quantification of NTBC in blood spots filter paper discs of 3.2mm diameter were extracted with 150 μL methanol containing mesotrione as internal standard (IS). Analysis was done by UPLC-MS/MS on a Xevo mass spectrometer (ESI+), (MRM). Parent ions were 330.05 for NTBC and 340.05 for IS, daughter ions were m/z 217.95 and m/z 125.95 for NTBC, and m/z 227.95 and m/z 103.95 for IS.

RESULTS

The calibration curve for NTBC in blood spots was linear from 0.1 μmol/L to 100 μmol/L. Recovery exceeded 73.1%, CV intraday and interday were below 9.6%. Instrumental run time was 2.5 min. Sensitivity of the method was 0.1 μmol/L. NTBC concentrations in plasma were higher than in blood spots by a factor of 1.56 ± 0.13.

CONCLUSION

As demonstrated in patients with tyrosinaemia type I quantification of NTBC by UPLC-MS/MS in blood spots is feasible and gives valuable information for monitoring NTBC treatment.

[Recommendations and management of type I hereditary or hepatorenal tyrosinemia]

Tyrosinemia type I is a potentially lethal disease if not diagnosed and treated properly. Diagnostic and therapeutic advances in recent years have significantly improved the prognosis for these patients. It is therefore important that the pediatrician has a clinical practice guideline with recommendations for diagnosis and treatment of this disease that leads to the appropriate intervention.

Clinical practice. NTBC therapy for tyrosinemia type 1: how much is enough?

Four patients with tyrosinemia type 1 (ages 6-32 months) were treated with 2-(2-nitro-4-trifluoro-methylbenzoyl)-1,3-cyclohexandion (NTBC) at Cairo University Children's Hospital, Egypt and followed up for 12-27 months. The recommended average dose of NTBC is 1 mg/kg/day. They were started on the following doses: 0.8, 0.58, 0.5, and 0.625 mg/kg/day, respectively. Two months after start of therapy, succinylacetone was undetectable in patients 1, 2, and 4, while in case 3, it was 5.4 microM. Her NTBC dose was increased from 0.5 to 0.65 mg/kg/day, and succinylacetone was undetectable 1 month later. They were kept on NTBC doses ranging from 0.55 to 0.65 mg/kg/day. These doses allowed catch up growth, normalization of synthetic liver functions, steep drop in serum alpha fetoprotein, reduction in phosphate loss in urine, normalization of serum calcium, phosphate, and alkaline phosphatase, and healing of active rickets. Succinylacetone was undetectable in urine on these doses.

IN CONCLUSION

Doses of NTBC, lower than recommended, may be helpful in treatment of tyrosinemia, on condition that succinylacetone production is suppressed, and AFP is maintained normal or showing a progressive decrease. This cost-effective dose may allow treatment of affected children from economically underprivileged countries, but longer follow up periods are needed.

The inclusion of succinylacetone as marker for tyrosinemia type I in expanded newborn screening programs

In expanded newborn screening programs by liquid chromatography/tandem mass spectrometry false negatives for tyrosinemia type I are a significant problem. We describe a method for inclusion of succinylacetone in order to avoid false negatives. We studied spots from 13,000 neonates born in Tuscany (January-May 2007) and ten spots from six patients with tyrosinemia type I. The traditional screening method was modified by adding dioxooctanoid acid (or 13C2-succinylacetone) as an internal standard to the methanolic solution of deuterated acylcarnitines and amino acids. A hydrazine solution was added to the mixture. The times of extraction, butylation and drying were only slightly prolonged. Specific multiple reaction monitoring for derivatized and labelled succinylacetone and dioxooctanoic acid was carried out. The assays were linear up to 100 micromol/L for succinylacetone. Intra- and inter-day imprecision data were in the range of 1.34% to 7.09% and 3.50% to 4.49%. Limits of detection and of quantification were 0.2 micromol/L and 0.4 micromol/L, respectively. Recovery ranged from 97.02% to 100.29%. Succinylacetone levels in samples from unaffected neonates were very close to the detection limit. Of the 46 recalls, eight (17.4%) were for abnormal tyrosine levels and all these cases had succinylacetone levels within the normal range (<2.4 micromol/L). In ten spots from six affected patients succinylacetone values ranged from 3.3 to 35.0 micromol/L. Including succinylacetone in newborn screening programs for amino acids and acylcarnitines avoids false-negative results for tyrosinemia type I. Newborn screening laboratories should consider implementing these modifications.

Stable isotope dilution analysis of N-acetylaspartic acid in urine by liquid chromatography electrospray ionization tandem mass spectrometry

N-acetylaspartic acid (NAA) is a specific urinary marker for Canavan disease, an autosomal recessive leukodystrophy. We developed a 'dilute and shoot' stable isotope dilution liquid chromatography tandem mass spectrometry (LC-MS/MS) method for determination of NAA in urine. Deuterated internal standard d(3)-NAA was added to untreated urine and the mixture was injected into the LC-MS/MS system operated in the negative ion mode. Chromatography was carried out on a C(8) minibore column using 50% acetonitrile solution containing 0.05% formic acid at a flow rate of 0.25 mL/min. The retention time was 1.6 min and the turnaround time was 2.2 min. NAA and d(3)-NAA were analyzed in multiple reaction monitoring mode. Calibrators and quality control samples were prepared in pooled control urine. The assay was linear up to 2000 micromol/L with limit of quantification at 1 micromol/L (S/N = 12). Interassay and intraassay coefficients of variation were less than 7% and recovery at three different concentrations was 98.9-102.5%. The LC-MS/MS method for NAA as described involves no extraction and no derivatization, showed no interference and gave excellent recovery with low variability and short analytical time. The method was successfully applied for the retrospective analysis of urine from 21 Canavan disease cases.

Determination of a new active steroid by high performance liquid chromatography with laser-induced fluorescence detection following the pre-column derivatization

A sensitive analytical method for the determination of a new active steroid, butane acid-(5-androsten-17-one-3beta-ol)-diester (A1998), was developed by high performance liquid chromatography with laser-induced fluorescence detection following the pre-column derivatization with dansylhydrazine. The calibration curve for A1998 derivatization was found linear in the dynamic range from 0.025 to 5.0 microg/ml, with the precision less than 6% (CV) and the mean extraction efficiency greater than 92%. In 200 microl of plasma samples the limit of quantitation was as low as 0.025 microg/ml with a signal-to-noise ratio of 10. This assaying was further applied to the determination of the pharmacokinetic parameters of A1998 in rats with an intravenous injection of A1998. Values for clearance for elimination, volume of distribution at steady state and terminal half life in the above case were determined as 50.3+/-1.1 ml/min kg, 1329.0+/-111.0 ml/kg and 44.0+/-2.7 min, respectively.

Analysis of organic acid markers relevant to inherited metabolic diseases by ultra-performance liquid chromatography/tandem mass spectrometry as benzofurazan derivatives

We describe a new approach applicable to the determination of organic acids that serve as diagnostic markers for several inherited metabolic disorders. We utilized liquid chromatography/tandem mass spectrometry for analysis of organic acid derivatives of a recently described benzofurazan reagent. The derivatization step was necessary to obtain organic acid derivatives suitable for analysis by reversed-phase liquid chromatography with high ionization efficiency for mass spectrometry in the positive-ion mode. In this work, a group of related dicarboxylic acid markers containing five or six carbon atoms were analyzed and validation was performed for glutaric and 3-hydroxyglutaric acids, the specific markers for glutaric acidemia type 1. Derivatization was achieved by reacting untreated urine with the derivatization reagent under mild conditions. The reaction mixture was analyzed on a C18 ultra-performance liquid chromatography (UPLC) column (50x2.1 mm, 1.7 microm) and detected in the multiple reaction monitoring mode in 5 min. Calibration curves were linear up to at least 1000 microM with detection limits for glutaric and 3-hydroxyglutaric acids of 0.025 and 0.02 microM, respectively (signal-to-noise ratio of 3). Intra-day (n=11) and inter-day (n=6) coefficients of variation were better than 11.2%. The assay was successfully applied to control (n=134) and glutaric acidemia type 1 (n=55) urine samples.

Analysis of succinylacetone, as a Girard T derivative, in urine and dried bloodspots by flow injection electrospray ionization tandem mass spectrometry

Flow injection electrospray ionization tandem mass spectrometric methods for succinylacetone (SA) in 250 microL urine, using d5-SA as internal standard, and in 3 mm dried bloodspots, using 13C4-SA as internal standard, are described. Selectivity and sensitivity of analysis is achieved by the use of a mono-Girard T derivative. Measured SA infant urine normal range (n=20) is 0.013-0.27 micromol/mmol creatinine. Measured SA newborn bloodspot normal range (n=152) is 0-0.30 micromol/L. Bloodspots from children with hepatorenal tyrosinemia type 1, and kept at room temperature for up to 7 years, afforded SA concentrations of 0.9-5.7 micromol/L.