Eleven novel mutations and clinical characteristics in seven Chinese patients with thiamine metabolism dysfunction syndrome

Thiamine metabolism dysfunction syndrome (THMD) comprises a group of clinically and genetically heterogeneous encephalopathies with autosomal recessive inheritance. Four genes, SLC19A3, SLC25A19, SLC19A2, and TPK1, are associated with this disorder. This study aimed to explore the clinical, biochemical and molecular characteristics of seven Chinese patients with THMD. Targeted next-generation sequencing of mitochondrial DNA and nuclear DNA was used to identify the causative mutations. The patients presented with subacute encephalopathy between the ages of 1-27 months. Brain magnetic resonance imaging (MRI) revealed abnormalities in the basal ganglia, indicating Leigh syndrome. Urine α-ketoglutarate in five patients was elevated. In four patients, five novel mutations (c.1276_1278delTAC, c.265A > C, c.197T > C, c.850T > C, whole gene deletion) were found in SLC19A3, which is associated with THMD2. In two patients, four novel mutations (c.194C > T, c.454C > A, c.481G > A, and c.550G > C) were identified in SLC25A19, supporting a diagnosis of THMD4. In one patient, two novel mutations (c.395T > C and c.614-1G > A) were detected in TPK1, which is indicative of THMD5. The patients received thiamine, biotin, and symptomatic therapy, upon which six patients demonstrated clinical improvement. Our findings expanded the phenotypic and genotypic spectrum of THMD, with eleven novel mutations identified in seven Chinese patients. Early diagnosis and treatment have a significant impact on prognosis.

α-Ketoglutaramate: an overlooked metabolite of glutamine and a biomarker for hepatic encephalopathy and inborn errors of the urea cycle

Glutamine metabolism is generally regarded as proceeding via glutaminase-catalyzed hydrolysis to glutamate and ammonia, followed by conversion of glutamate to α-ketoglutarate catalyzed by glutamate dehydrogenase or by a glutamate-linked aminotransferase (transaminase). However, another pathway exists for the conversion of glutamine to α-ketoglutarate that is often overlooked, but is widely distributed in nature. This pathway, referred to as the glutaminase II pathway, consists of a glutamine transaminase coupled to ω-amidase. Transamination of glutamine results in formation of the corresponding α-keto acid, namely, α-ketoglutaramate (KGM). KGM is hydrolyzed by ω-amidase to α-ketoglutarate and ammonia. The net glutaminase II reaction is: L - Glutamine + α - keto acid + H2O → α - ketoglutarate + L - amino acid + ammonia. In this mini-review the biochemical importance of the glutaminase II pathway is summarized, with emphasis on the key component KGM. Forty years ago it was noted that the concentration of KGM is increased in the cerebrospinal fluid (CSF) of patients with hepatic encephalopathy (HE) and that the level of KGM in the CSF correlates well with the degree of encephalopathy. In more recent work, we have shown that KGM is markedly elevated in the urine of patients with inborn errors of the urea cycle. It is suggested that KGM may be a useful biomarker for many hyperammonemic diseases including hepatic encephalopathy, inborn errors of the urea cycle, citrin deficiency and lysinuric protein intolerance.

[Urine metabonomic study of intervention effects of Morinda officinalis how. on 'kidney-yang deficiency syndrome']

To investigate the intervention effects of Morinda officinalis How. on 'Kidney-yang deficiency syndrome' induced by hydrocortisone in rats, the metabolic profiles of rat urine were characterized using proton nuclear magnetic resonance and principal component analysis (PCA) was applied to study the trajectory of urinary metabolic phenotype of rats with 'Kidney-yang deficiency syndrome' under administration of M. officinalis at different time points. Meanwhile, the intervention effects of M. officinalis on urinary metabolic potential biomarkers associated with 'Kidney-yang deficiency syndrome' were also discussed. The experimental results showed that in accordance to the increased time of administration, an obvious tendency was observed that clustering of the treatment group moved gradually closed to that of the control group. Eight potential biomarkers including citrate, succinate, alpha-ketoglutarate, lactate, betaine, sarcosine, alanine and taurine were definitely up- or down-regulated. In conclusion, the effectiveness of M. oficinalis on 'Kidney-yang deficiency syndrome' is proved using the established metabonomic method and the regulated metabolic pathways involve energy metabolism, transmethylation and transportation of amine. Meanwhile, the administration of M. officinalis can alleviate the kidney impairment induced by 'Kidney-yang deficiency syndrome'.

[Study on influence of glucoside Tripterygium total tablets on metabolism in rats by NMR metabonomic technique]

OBJECTIVE

To investigate the toxic effects of Glucoside Tripterygium total on rats with nuclear magnetic resonance (NMR)-based metabonomic method.

METHOD

The influence of intragastric administration of Glucoside Tripterygium total suspension at two different doses on endogenetic metabolites in normal rat urine was determined with bio-NMR method then analyzed by pattern recognition technique and partial least-squares discriminant analysis (PLS-DA). Histopathological analysis was carried out.

RESULT

Escalations of concentrations of urinary taurine, TMAO and glucose as well as reductions of concentrations of urinary citrate and 2-oxoglutarate were found by analysis of the 1H-NMR spectra, which was coincident with the result of histopathological analysis. The result of pathological examination indicated that pathologic change was not observed in nephridial tissue, but there were obvious changes in hepatic tissue.

CONCLUSION

The urinary metabomic spectra were closely associated with the hepatic toxicity, which manifested the mitochondrial dysfunctions, the abnormal energy metabolism in TCA cycle as well as the abnormal glucose metabolism.

Toxicometabolomics of urinary biomarkers for human gastric cancer in a mouse model

Toxicometabolomics of urinary biomarkers for human gastric cancer in a mouse model was investigated using (1)H-nuclear magnetic resonance (NMR) spectroscopy. A human gastric adenocarcinoma cell line (1 × 10(7) cells/ml) was grafted onto the skin of the back of intact male BALB/c-nu/nu mice. After the xenografted tumors developed, urine was collected and analyzed for endogenous metabolites. Global profiling combined with principal components analysis (PCA), partial least squares-discriminant analysis (PLS-DA), and orthogonal projections to latent squares-discriminant analysis (OPLS-DA) showed distinct separation of clusters between control and tumor-bearing mice. Targeted profiling revealed significant changes in trimethylamine oxide (TMAO), 3-indoxylsulfate, hippurate, and citrate levels in mice carrying human gastric cancer cells compared to normal mice. The levels of TMAO (0.41-fold) and hippurate (0.26-fold) in tumor-bearing mice were significantly decreased, whereas the levels of 3-indoxylsulfate (3.39-fold), 2-oxoglutarate (2.32-fold), and citrate (1.9-fold) were significantly increased in urine samples of tumor-bearing mice. Data suggest that TMAO, hippurate, 3-indoxylsulfate, 2-oxoglutarate, and citrate may serve as useful urinary biomarkers for gastric tumorigenesis in a mouse model.

Renal excretion of pyruvate, lactate and alpha-ketoglutarate in kidney donors before and after nephrectomy and in patients with terminal uremia

The excretional patterns of lactate, pyruvate and alpha-ketoglutarate have been investigated in 7 patients with terminal uremia and in 10 kidney donors with normal renal function before and after unilateral nephrectomy. Methods for analysis of the three substances in urine were elaborated. In all patients, the levels of renal excretion of lactate and pyruvate were very low, and clearance values were independent of the glomerular filtration rate (GFR). alpha-ketoglutarate clearance varied to some extent with renal function, but no correlation to GFR was found, and exceeded the GFR in uremic patients, indicating that the net result of renal handling of alpha-ketoglutarate may be a tubular secretion.

The excretional patterns of lactate, pyruvate and alpha-ketoglutarate in renal transplants

The excretional patterns of lactate, pyruvate and alpha-ketoglutarate were investigated after renal transplantation in 36 patients. Fourteen patients had received a living-donor kidney with short ischemia time and good initial graft function, 22 had a cadaver transplant with an initial 125iothalamate clearance of more than 6 ml/min. The excretion of lactate and pyruvate did not vary significantly from that seen in normal controls or patients with uremia. In six patients with cadaver transplants, clearance values of alpha-ketoglutarate exceeded that of the glomerular filtration rate, indicating a net tubular secretion of this substance. During acute rejection episodes in 5 patients, no changes were seen in the excretional patterns of lactate, pyruvate and alpha-ketoglutarate.

[Metabonomics profile of urine from rats administrated with different treatment period of isoniazid]

OBJECTIVE

To study the effect of different treatment period, of isoniazid (INH) on the metabonomic profile of rat urine and its relationship with traditional toxicity evaluation of blood biochemical indicators and histopathology and to explore the feasibility of metabonomics in the application of drug toxicity.

METHODS

Sixty male Wistar rats were orally administrated with 0, 50, 100, 200, and 400 mg x kg(-1) INH for 3, 7, and 14 days, respectively. Rat urine was then collected and its 1H nuclear magnetic resonance (NMR) spectra were acquired. All animals underwent traditional toxicity evaluation.

RESULTS

Hepatotoxicity was revealed by traditional toxicity evaluation in rats treated with higher dosage and longer treatment of INH. Time-response relationship existed during the treatment. Time-dependent metabonomics changes conformed with the results of traditional toxicity evaluation. The urine metabonomics showed a trajectory bias from those of the controls or pre-administration, and such bias exaggerated along with the prolongation of treatment, indicating a severer toxic injury. Along with the increase of the concentrations of urinary taurine and glucose and the decrease of the concentrations of urinary citrate and 2-oxoglutarate, the 1H NMR spectra of urine in rats treated with INH also changed.

CONCLUSIONS

The metabonomics technique can distinguish the onset and development of toxicity, which helps track and identify biomarkers. The hepatic toxicity induced by INH is related to the injury of mitochondrial function, reduction of energy metabolism in tricarboxylic acid cycle, and perturbations in the metabolism of glucose and lipid. The effect of INH on the rat urine metabonomic profile is related with INH toxicology. Therefore, metabonomics can be recognized as an ideal technique to explore and evaluate the drug toxicities.

Investigations into Biochemical Changes of Genetic Hypertensive Rats Using 1H Nuclear Magnetic Resonance-Based Metabonomics

Genetically hypertensive rats provide a simple and accessible model for studying essential hypertension, which is a polygenic, heterogenous and multifactorial disease. Their genetic and metabolic features are of great interest because they may provide insight into the pathophysiological processes underlying essential hypertension. We have investigated the genetic influence on metabolic balance and metabolite excretion patterns in stroke-prone spontaneously hypertensive rats (SHRSP) with established hypertension using 1H NMR-based metabonomics. Urinary metabolite profiles for SHRSP and their age-matched normotensive controls, Wistar Kyoto rats, were acquired using 1H NMR spectroscopy. Principal components analysis was applied to these complex NMR data to facilitate differentiation and determine metabolic differences between urine samples collected from the hypertensive and normotensive rats. Consequently, it was possible to distinguish urine samples between the two strains in the principal components scores plot. The loadings plot showed that taurine, creatine and some unidentified metabolites resonating at around delta 2.48, 3.10 and 3.58 predominantly contributed to the separation. In SHRSP, the urinary levels of taurine and creatine were found to be higher and the intensities of the unknown signals much lower than those in the Wistar Kyoto rats. Although the pathophysiological significance of these components remains to be elucidated, this study suggests that 1H NMR-based metabonomics is a promising approach to provide new information on metabolic changes related to the pathophysiological processes of the genetically hypertensive rats.

A metabonomic investigation of the biochemical effects of mercuric chloride in the rat using 1H NMR and HPLC-TOF/MS: time dependent changes in the urinary profile of endogenous metabolites as a result of nephrotoxicity

The effects of the administration of a single dose of the model nephrotoxin mercuric chloride (2.0 mg kg(-1), subcutaneous) to male Wistar-derived rats on the urinary metabolite profiles of a range of endogenous metabolites has been investigated using (1)H NMR and HPLC-MS. Urine samples were collected daily for 9 days from both dosed and control animals. Analysis of these samples revealed marked changes in the pattern of endogenous metabolites as a result of HgCl(2) toxicity. Peak disturbances in the urinary metabolite profiles were observed (using both NMR and HPLC-MS) at 3 days post dose. Thereafter the urinary metabolite profile gradually returned to a more normal composition. Markers of toxicity identified by (1)H NMR spectroscopy were raised concentrations of lactate, alanine, acetate, succinate, trimethylamine (TMA), and glucose. Reductions in the urinary excretion of citrate and alpha-ketoglutarate were also seen. Markers identified by HPLC-MS, in positive ion mode, were kynurenic acid, xanthurenic acid, pantothenic acid and 7-methylguanine which decreased after dosing. In addition an ion at m/z 188, probably 3-amino-2-naphthoic acid, was observed to increase after dosing. As well as these identified compounds other ions at m/z 297 and 267 decreased after dosing. In negative ion mode a range of sulfated compounds were observed, including phenol sulfate and benzene diol sulfate, which decreased after dosing. As well as the sulfated components an unidentified glucuronide at m/z 326 was also observed to decrease after dosing. The results of this study demonstrate the complementary nature of the NMR and MS-based techniques for metabonomic analysis.

Urinary α-ketoglutarate is elevated in patients with hyperinsulinism-hyperammonemia syndrome

BACKGROUND

Congenital hyperinsulinism (CHI) is the most frequent cause of recurrent episodes of hypoglycemia in infancy and results from different underlying genetic defects. The hyperinsulinism-hyperammonemia syndrome (HHS) has been shown to result from dominant germ line mutations within the glutamate dehydrogenase gene (GLUD1, OMIM *138130). Diagnosis of this entity is of clinical importance since invasive diagnostic procedures which are performed to identify focal pancreatic lesions are not necessary in HHS. Therefore, we investigated whether urinary concentration of alpha-ketoglutarate (alpha-KG) is elevated in patients with hyperinsulinism.

METHODS

Excretion of alpha-KG was measured by gas-chromatography/mass spectrometry (GC/MS) in eight patients with an activating GLUD1 mutation and 90 controls.

RESULTS

Urinary alpha-KG was significantly elevated in seven of eight patients when compared to controls. Hyperammonemia was found in six of the eight patients with HHS. No relation was found between the underlying GLUD1 mutation and the level of urinary alpha-KG as well as the presence or absence of hyperammonemia.

CONCLUSION

Urinary alpha-KG is elevated in most patients with HHS and should be included in the work-up of patients with hyperinsulinism.

Amish lethal microcephaly: a new metabolic disorder with severe congenital microcephaly and 2-ketoglutaric aciduria

A new metabolic disorder characterized by severe congenital microcephaly, death within the first year, and severe 2-ketoglutaric aciduria has been found among the Old-Order Amish of Lancaster County, Pennsylvania. Amish lethal microcephaly segregates as an autosomal recessive disorder and has an unusually high incidence of at least 1 in 500 births. When the infants are well, the urine organic acid profiles show isolated, extreme elevations of 2-ketoglutaric acid. However, during otherwise simple viral illnesses, the infants often develop a metabolic acidosis, which may follow a lethal course. Cranial magnetic resonance imaging of a single patient showed a smooth, immature brain similar to that of a 20-week fetus except for a moderate degree of cerebellar vermal hypoplasia. Assay of 2-ketoglutarate dehydrogenase in cultured lymphoblasts of one patient showed normal activity. Amish lethal microcephaly maps to 17q25 and may be caused by a defect in a mitochondrial inner membrane protein functioning as a 2-ketoglutarate transporter.

[Mitochondrial DNA T to G mutation 8993 in Leigh encephalopathy and organic aciduria]

We report a 10-month-old female infant with Leigh encephalopathy caused by a T to G mutation at nucleotide 8993 of mitochondrial DNA. Initial manifestations were diarrhea and pyrexia, followed by disturbance of consciousness. Blood chemistry showed lactic acidosis, and cranial T2 weighted magnetic resonance imaging demonstrated symmetric high-intensity areas in the basal ganglia, consistent with Leigh encephalopathy. Analysis of urinary organic acids revealed a increase of alpha-ketoglutamate. Derivatives of branched chain amino acids, which accumulate in maple syrup disease, were also increased. Lipoamide dehydrogenase (E3) deficiency was initially suspected; however, normal activity of pyruvate dehydrogenase complex excluded the diagnosis. The organic aciduria disappeared after two weeks. The CNS lesions in our case were observed more prominently in the floor of the bilateral frontal lobes than in the globus pallidus and putamen. In this case, mitochondrial DNA mutation may have caused organic aciduria and the atypical imaging findings.

2-ketoglutarate dehydrogenase deficiency with intermittent 2-ketoglutaric aciduria

2-ketoglutarate dehydrogenase (KGD) deficiency is a rare disorder of the tricarboxylic acid cycle. To date, 7 patients have been reported with clinical symptoms suggesting a neurodegenerative disease. We report a new patient in whom urinary excretion of 2-ketoglutaric acid (KGA) was intermittently found to be within normal ranges. At birth, the male patient suffered from mild perinatal asphyxia due to meconium aspiration. During the first months of life, he developed an opisthotonus, hyperexcitability and truncal hypertonia. At the present age of 14 months, these neurological symptoms became less pronounced. A cranial MRI was normal. Urinary 2-KGA excretion was found to be intermittently increased in 3 of 6 analyses between 2 weeks and 14 months of age (5-1700 mmol/mol creatinine, controls: < 340 mmol/mol creatinine). 2-KGA was not increased in plasma and CSF. Diagnosis was confirmed by measurement of decreased 2-KGD activity in cultured skin fibroblasts. This report demonstrates that the diagnosis of 2-KGD deficiency can easily be missed. In case of doubt, 2-KGD activity should be measured in fibroblasts. The clinical and long-term outcome of patients with 2-KGD deficiency is unknown. Further reports and long-term evaluation are required.

Hyperinsulinaemic hypoglycaemia associated with persistent hyperammonaemia

Two cases of hyperinsulinaemic hypoglycaemia associated with persistent hyperammonaemia in unrelated infants of 7 days and 4 months of age are reported. Blood ammonia levels were 100-300 micromol/l (normal values <40 micromol/l). The hyperammonaemia was asymptomatic and not associated with any of the abnormalities of amino acids or organic acids observed in urea cycle enzyme defects. Orotic aciduria was normal. The hyperammonaemia was not influenced by the levels of blood glucose nor by subtotal pancreatectomy. On admission blood glucose was ca. 1.2 mmol/l (21.6 mg/dl) corresponding to blood insulin levels of 35 and 22 mU/l respectively in both infants. Continuous intravenous glucose perfusion was necessary to prevent hypoglycaemia. Furthermore 2-oxoglutaric acid in urine was increased in the second infant to 3.15 mg/mg creatinine (normal 0.41+/-0.12). This may point to mutations in the glutamate dehydrogenase gene.

CONCLUSION

2-Oxoglutaric aciduria may be an important clue to the diagnose in this syndrome.

Comparison of urinary component levels in 4 strains of mice with different physiological characteristics

Changes in urinary component levels before, during and after reproduction were examined with 1H-nuclear magnetic resonance (NMR) in four strains of female mice with different mammary tumour potential and related characteristics (SHN, SLN, GR/A and C3H/He). Regardless of the variations in these changes among the strains, the urinary component levels reflected physiological changes during reproduction and some strain-specific characteristics. The urinary excretion of citrate, 2-oxoglutarate and lactate increased from the virginal stage to pregnancy and declined during lactation in all strains, indicating a marked change in sugar metabolism during reproduction. SHN and SLN, which are from the same basal stock, showed a similar pattern and the level, of several components were lower than those of GR/A and C3H/He. The levels of some lower components were compensated for by higher urine excretion. The levels of taurine and betaine, both essential for fetal and pup growth, increased at lactation in only GR/A, reflecting the poorer pup growth observed in this strain. Finally, the 1H-NMR method was useful to estimate not only the metabolic but also the physiological changes of the animals without invasion, pain or distress and would thus contribute to animal welfare in the animal experiments.

alpha-Ketoglutarate assay based on fluorescence quenching by NADH

A new assay procedure for the measurement of ketoglutarate concentrations is described which is based on substrate-induced quenching (SIQ) of a fluorophore. The method makes use of the photoreaction between a fluorophore (thionine) and NADH. The latter is consumed during an enzymatic reaction between ketoglutarate and L-glutamic dehydrogenase. The conversion yield of cofactor from its reduced form to oxidized forms represented as an overall change in the population of the excited state population of the fluorophore thionine. An empirical relation is described that correlates initial substrate concentration to the observed yield of the cofactor conversion via a fluorescence recovery constant,Kt. The analysis of data obtained over a range of 0-500 microM results in a constant of 2748 M-1. The applicability of the proposed method is demonstrated by performing the assay for alpha-ketoglutarate in human urine. The ketoglutarate SIQ assay was not affected by the background interference that is inherent to this complex matrix.

Increased urinary excretion of analogs of Krebs cycle metabolites and arabinose in two brothers with autistic features

A marked increase in analogs of Krebs cycle metabolites was found in the urine of two brothers with autistic features. These metabolites included citramalic, tartaric (3-OH-malic), and 3-oxoglutaric acids and compounds tentatively identified as a citric acid analog and partially identified as a phenylcarboxylic acid by the fragmentation pattern of the trimethylsilyl (TMS) derivatives of the compounds and mass shifts of the same compounds derivatized with perdeuterated N,O-bis(trimethylsilyl)trifluoroacetamide. The molecular mass of the TMS derivative of the tentatively identified citric acid analog was 596 Da, based on a finding of a significant M - 15 ion at m/z 581. The citric acid analog was excreted in quantities as high as 137 mmol/mol creatinine, based on the response factor of citric acid as a surrogate calibrator. A carbohydrate with a retention time and mass spectrum identical to arabinose was also found in high concentrations in the urine of these brothers.

High-resolution proton nuclear magnetic resonance studies of urine from asphyxiated newborn infants

High-resolution proton nuclear magnetic resonance spectroscopy was used to study human urine obtained from 10 normal babies and twenty babies with various degrees of neonatal asphyxia, respiratory distress syndrome (RDS), and meconium aspiration syndrome (MAS). All sick babies showed different degrees of oxygen deficiency, indicated by an obvious increase of the lactate signal level in the urine spectra. Changes in the concentration of other urinary metabolites produced from the citric acid cycle were also observed. In extremely serious cases, the signals of some of the major components, including citrate, alpha-ketoglutarate, and succinate, simply disappeared. The spectra of urine, serum, and CSF of an infant suffering from SIDS showed common characteristics of the metabolites.

Urinary organic anion excretion in response to dietary acid and base loading

Animals eating a base-loaded or base-forming diet excrete urine containing large amounts of organic anions (OA). Although citrate is the only OA previously identified as being excreted in appreciable amounts during base loading, citrate excretion accounts for only part of total OA excretion. The objectives of this study were to identify other OA excreted by rats and to see how their excretion changed in response to moderate (8 micro Eq/g per day) and heavy (30 micro Eq/g per day) loads of NaHCO3 and NH4Cl. Urinary OA were identified by high-performance liquid chromatography and were measured by enzymatic techniques as well. It was found that, in addition to citrate, significant quantities of alpha-ketoglutarate (alpha-KG) were excreted by base-loaded rats and that the excretion of citrate, alpha-KG, and succinate increased with base loading and decreased with acid loading. Citrate plus alpha-KG excretion rates were, respectively, two-thirds and one-third the rate of HCO3- excretion in rats given moderate and heavy base loads. The excretion of creatinine, glutamine, and hippurate showed no clear pattern in response to acid or base loading. It was concluded that, especially in animals experiencing moderate base loads, increases in the excretion of citrate and alpha-KG represent a much more significant component of base excretion than has been recognized previously.

A new patient with alpha-ketoglutaric aciduria and progressive extrapyramidal tract disease

A 4.5-year-old boy with chronic progressive encephalopathy is described. The clinical presentation initially included seizures and hypotonia which later evolved into severe extrapyramidal disease and dementia. The gas chromatography/mass spectrometry (GC/MS) analysis of urine indicated that alpha-ketoglutarate was increased 210 times and aconitic acid 80 times. No disturbance of acid/base balance, lactic acid or ammonia metabolism accompanied this clinical picture. The fibroblasts contained 29% of normal alpha-ketoglutarate dehydrogenase activity, while the activity of another mitochondrial marker enzyme, glutamate dehydrogenase, was normal. The neuroimaging studies revealed bilateral striatal necrosis. The clinical and biochemical findings were almost identical to two previously reported patients. Experience with this patient emphasizes the need for detailed organic acid biochemical investigation in any progressive encephalopathy and that extrapyramidal tract signs should evoke the possibility of alpha-ketoglutaric aciduria, among other 'neurologic organic acidemias'.

DOOR syndrome (deafness, onycho-osteodystrophy, and mental retardation): a new patient and delineation of neurologic variability among recessive cases

We report the seventeenth case of the recessive form of the DOOR syndrome. The parents were Guatemalan and not known to be consanguineous. The patient had developmental delay, severe sensorineural deafness, and abnormal nails and phalanges in the hands and feet. Urinary 2-oxoglutarate excretion was normal. The patient was among a subset of DOOR syndrome patients without seizures in infancy. This observation may be useful in discussing the prognosis for newly identified cases.

Octenylsuccinic aciduria in children fed protein-hydrolysate formulas containing modified cornstarch

The excretion of 2-(2'-octenyl)succinic acid (OSA) and several metabolites of OSA was studied by gas chromatography/mass spectrometry in 17 infants and children fed one of three proprietary elemental or protein-hydrolysate formulas that use OSA-modified cornstarch as an emulsifying agent. Variable but often large amounts (up to 2500 mg/g creatinine) of the fatty acid-like OSA and its metabolites were found in the urine of these children, and levels of OSA in their blood ranged from 9.5 to 57.9 mumol/L. Apparently secondary abnormalities, such as increased urinary levels of glutaric acid and 2-ketoglutaric acid, were also found in more than half of the urine specimens. The molecular weight and mass fragmentation patterns of the nine compounds associated with the excretion of OSA are consistent with the proposal that OSA is metabolized in human infants and children by a combination of omega-, omega-1-, and beta-oxidation steps, similar to the metabolism of another branched-chain fatty acid, valproic acid. The urinary organic acid pattern of children fed elemental formulas containing OSA-modified starch often was dominated by OSA and its metabolites, and in several children the OSA-related changes were mistaken for a primary metabolic disease. Physicians and laboratories evaluating children for suspected metabolic diseases should be aware of the possibility of abnormal organic acid studies associated with OSA-containing formulas.

Effect of aging and diet on proton NMR spectra of rat urine

500 MHz 1H NMR studies of rat urine are used to assess metabolic changes resulting from aging (0.5-20 months) and changes in diet (casein versus chow). Aging rats fed chow diets decrease their excretion of citrate and 2-oxoglutarate, while the output of taurine and creatinine increases. Only young rats (1 month or less postweaning) excrete significant amounts of betaine and trimethylamine-N-oxide. Rats fed casein diets for 1 month postweaning do not excrete 2-oxoglutarate and excrete lower levels of hippurate, succinate, and citrate compared to rats fed chow diets. They also excrete N-methylnicotinamide. These high resolution proton NMR studies provide metabolic profiles which are not readily available by other techniques.

Biotin-responsive infantile encephalopathy: EEG-polygraphic study of a case

A case of an infant suffering from progressive lethargy, sparse scalp hair, autistic-like behavior, myoclonias, and drug-resistant generalized seizures is reported. Laboratory investigations revealed, in the absence of metabolic acidosis, an increased urinary excretion of 2-ketoglutaric acid and a small peak of 3-hydroxyisovaleric acid. The serum biotinidase activity was 0.15 nmol min-1 ml-1 (normal range 5.2 +/- 0.9) in the propositus and 0.310 and 0.420 in her father and mother, respectively. The interictal EEG showed multifocal abnormalities; numerous seizures were recorded, with the pattern of true tonic-clonic fits, exceptional in infancy. Also myoclonias, auditory myoclonus, and repetitive startles were documented. Because of dramatic improvement of all symptoms and signs after starting biotin (5 mg twice daily), the authors suggest a therapeutical trial in all drug-resistant infantile seizures.

Quantitative high resolution 1H NMR urinalysis studies on the biochemical effects of cadmium in the rat

Quantitative changes in the urinary excretion patterns of low molecular weight compounds were followed for up to 30 days after dosing of adult Sprague-Dawley rats with single intraperitoneal injections of CdCl2 (6-24 mumol/kg), using high resolution 1H NMR multicomponent urinalysis. There was a marked reduction in the rate of urinary excretion of citrate, 2-oxoglutarate, and succinate within 4.5 hr of the administration of 24 mumol/kg Cd2+. This continued for up to 4 days after dosing in male rats and was consistent with a renal tubular acidosis, caused by inhibition of carbonic anhydrase. Histological examination of the kidneys showed no evidence of structural abnormalities at any Cd2+ dose level. Creatinine excretion was not affected by Cd2+ treatment at any dose level but hippurate excretion was significantly reduced. Severe testicular damage was noted within 24 hr of Cd2+ treatment at doses of greater than 9 mumol/kg and the degree of damage appeared to be correlated with the presence of large amounts of creatine (up to 20 mM) in the urine. Analysis of homogenates of healthy testicular material indicated the presence of high concentrations of free creatine. Cadmium-induced creatinuria appears to result from direct release of creatine from the necrotic cells of the seminiferous tubules and, hence, the measurement of creatine excretion rates may provide a useful noninvasive indicator of testicular necrosis. Because NMR is nonselective in terms of metabolite detection, this work has shed new light on the changes in urinary composition arising from Cd toxicity. As such, the technique is potentially very valuable in the search for new metabolic markers of toxicity and organ dysfunction.

Transport and utilization of alpha-ketoglutarate by the rat kidney in vivo

In order to establish the characteristics of net renal transport and utilization of alpha-ketoglutarate (alpha-KG) in the rat, we have precisely quantified the renal blood flow, the urinary flow and the rates of alpha-KG delivery, filtration, reabsorption or secretion, excretion, uptake or production by an in vivo rat kidney preparation. In normal rats, alpha-KG uptake was higher than alpha-KG reabsorption at both endogenous and elevated plasma alpha-KG concentrations; thus, a net peritubular transport, which was the main supplier of alpha-KG to the renal cells, took place. Saturation of reabsorption and peritubular transport of alpha-KG occurred at blood alpha-KG concentrations about 30 and 150 times above normal, respectively. Acute metabolic acidosis was found to have no effect on renal handling of alpha-KG. At endogenous plasma alpha-KG concentrations, alkalosis converted net renal uptake into net renal production of alpha-KG resulting in addition of alpha-KG by the renal cells both to blood and to the luminal fluid. Elevation of blood alpha-KG concentration restored the renal uptake of alpha-KG. This uptake, which was entirely accounted for by the peritubular transport of alpha-KG, reached a maximum which was lower than that observed in normal and acidotic rats.

Changes in albumin levels in blood and urine of Microtus montanus chronically infected with Trypanosoma brucei gambiense

Serum albumin and glucose concentrations and urinary excretion of alpha-keto acids and proteins were determined in samples obtained throughout a chronic Trypanosoma brucei gambiense infection in Microtus montanus. An increase in urinary excretion of alpha-keto acids and proteins during the terminal stage of disease was accompanied by a decrease in serum glucose concentration. This terminal hypoglycemia reflected a depletion of liver glycogen in most animals. In contrast (and the major focus of this study) serum albumin concentration was decreased by the second week of infection and in the final sample obtained was less than 50% of that measured in preinfection samples. Female animals survived approximately 1 wk longer than males and were less susceptible during the acute phase of disease. This relative resistance was most likely due to the fact that female animals were relatively more efficient in limiting parasitemia during the first week of infection. The similarity between humans and voles in terms of protein and alpha-keto acid excretion and changes in serum concentrations of glucose and albumin during trypanosome infection further validate the use of Microtus as an experimental model for trypanosomiasis in humans.

Organic aciduria in rats fed high amounts of xylitol or sorbitol

The acidification of urine during polyol feeding was investigated with 27 Long-Evans male rats (aged 12 weeks) which were fed a xylitol diet (X), a sorbitol diet (S), or a basal diet for 4 weeks. The amount of polyols in the diet was increased from 5% to the final 20% level within 3 weeks. The polyol-fed animals showed reduced weight gain, lowered urine pH (from 6.5 to 5.6), and a 4-fold increase in the titratable acid excretion. X and S increased the daily urine volumes by 49 and 63%, respectively, but did not affect the wet weight or the pH values of the feces. as chromatographic-mass spectrometric analyses of organic acids revealed highly increased amounts of methylmalonic acid (13- to 20-fold) and 2-oxoglutaric acid (4- to 5-fold) in the urine of polyol-fed rats. The urinary excretion of citric acid and malic acid was also increased significantly (2- to 4-fold). The acidity of urine was not reflected in the blood acid-base balance of the animals. The increases in the levels of urinary organic acids in the polyol-fed rats were explained in terms of impaired mitochondrial oxidation of these acids and of impaired conversion of methylmalonic acid to succinic acid.

Urinary organic acids: isolation and quantification for routine metabolic screening

A method for isolating organic acids from acidified urine on an equivolume mixture of Porapak Q and Porapak T is described, and results are compared with extraction with ethyl acetate and ion exchange on DEAE-Sephadex. Average recoveries of 14C-labeled oxalic acid, lactic acid, succinic acid, alpha-ketoglutaric acid, citric acid, and cinnamic acid were equal to or better than those obtained with the solvent-extraction method. The ion-exchange method gave higher recoveries for oxalic acid, lactic acid, and citric acid. The quantification of separated acids from reconstructed mass spectrometric ion traces is compared with quantification from the simultaneously recorded flame ionization detector response signals. A good correlation was obtained. With the present routine metabolic screening method we have detected several patients with inborn errors of metabolism.

Urinary excretion of lactate, 2-oxoglutarate, citrate, and glycerol in patients with glycogenosis type I

Growth retardation and lactic aciduria are well-known abnormalities in patients with a deficiency of either glucose-6-phosphatase or glucose-6-phosphate translocase. In 19 patients with glucose-6-phosphatase and two patients with glucose-6-phosphate translocase, growth retardation was quantified by calculating the height standard deviation score. The urinary excretion of lactate and some other metabolites was quantified by calculating the lactate/creatinine, 2-oxoglutarate/creatinine, citrate/creatinine, and glycerol/creatinine ratios in urine. Significant correlations were found between the lactate/creatinine ratio, the 2-oxoglutarate/creatinine ratio, and height SD score. Urinary lactate appeared to respond promptly to changes of the diet, while urinary 2-oxoglutarate responded only slowly, as did growth itself. The citrate/creatinine ratio and the glycerol/creatinine ratio were within the normal range and varied little. It was concluded that the urinary 2-oxoglutarate excretion primarily reflects the severity of the disease as expressed in stunted growth. Thus, while urinary lactate levels are more suitable for monitoring the diet, urinary 2-oxoglutarate levels can be used as an indication for intensive treatment with hyperalimentation.

Multiple alpha-keto aciduria in Microtus montanus chronically infected with Trypanosoma brucei gambiense

Microtus montanus chronically infected with a monomorphic strain of Trypanosoma brucei gambiense excreted in urine greatly elevated quantities of not only the aromatic alpha-keto acids, phenylpyruvic and 4-hydroxyphenylpyruvic acids, but also two aliphatic alpha-keto acids, pyruvic and alpha-ketoglutaric acids. Elevated keto acid excretion began approximately midway through infection and quantities remained elevated until death. Daily keto acid excretion did not correlate with daily parasitemia. Thus, a large metabolic disturbance exists in laboratory animals infected with African trypanosomes. The multiple alpha-keto aciduria potentially contributes to the pathogenesis of chronic African trypanosomiasis.

Metabolism in vivo of furazolidone: evidence for formation of an open-chain carboxylic acid and alpha-ketoglutaric acid from the nitrofuran in rats

The in vivo metabolism of an antibacterial nitrofuran, furazolidone [N-(5-nitro-2-furfurylidene)-3-amino-2-oxazolidone] was investigated. When the nitrofuran was administered orally to rats, two new-type nitrofuran metabolites, N-(4-carboxy-2-oxobutylideneamino)-2-oxazolidone and alpha-ketoglutaric acid, were isolated from the urine, together with 3-(4-cyano-2-oxobutylideneamino)-2-oxazolidone and N-(5-acetamido-2-furfurylidene)-3-amino-2-oxazolidone. In addition, the present study showed that the corresponding aminofuran was an intermediate in the conversion of furazolidone to these metabolites.

Kinetics and metabolic effects of orally administered ornithine alpha-ketoglutarate in healthy subjects fed with a standardized regimen

In accordance with previous results obtained with traumatized patients, ornithine alpha-ketoglutarate (OKG) was orally administered to 10 healthy subjects fed with a standardized regimen. Six similarly fed control subjects received only water. Plasma and 24-h urinary amino acids and alpha-ketoglutarate, plasma glucose, plasma insulin, and urine urea were all measured. After administration of ornithine alpha-ketoglutarate, the rapid decrease in blood ornithine to basal values, the absence of any increase in plasma alpha-ketoglutarate levels, and the minimal increase in ornithine, alpha-ketoglutarate, and urea urinary elimination, all indicated intense metabolism and utilization of the two compounds. These results suggest that the hyperornithinemia observed in 4-h fasting, traumatized patients receiving ornithine alpha-ketoglutarate reflects a metabolic perturbation in the utilization of this amino acid after trauma, rather than a hypothetical slow utilization. On the other hand, ornithine alpha-ketoglutarate induced an increase in insulin levels causing hypoglycemia and probably a decrease in plasma levels of several amino acids.

Studies of urinary organic acid profiles of a patient with dihydrolipoyl dehydrogenase deficiency

Using gas chromatography-mass spectrometry (GC/MS), urinary organic acid profile studies were carried out on a patient with dihydrolipoyl dehydrogenase (E3) deficiency. Elevated levels of 2-hydroxyglutaric acid, 2-hydroxyisocaproic acid and 2-oxoisocaproic acid were observed in addition to lactic acid, 2-oxoglutaric acid, 2-hydroxyisovaleric acid and 2-hydroxybutyric acid previously described in patients with E3 deficiency. The 2-oxoglutaric acid levels were significantly lowered after branched-chain amino acid restriction. In an acute period, the patient was slightly ketoacidotic and excreted larger amounts of 2-oxoglutaric acid and lactic acid than in a static period. It was shown that, prior to confirmatory enzyme studies, patients with E3 deficiency who were suspected to have atypical maple syrup urine disease or chronic lactic acidosis can be rapidly identified by GC/MS analysis of urinary acids.

Organic acids and branched-chain amino acids in body fluids before and after multiple exchange transfusions in maple syrup urine disease

We successfully treated a critically ill infant with the classical type of maple syrup urine disease by multiple exchange transfusions via a peripheral artery and vein and with positive calorie supplementation in the early stage of therapy. Clinical improvement was definite after the plasma leucine level fell below 1 mmol/l. There was a close linear correlation between plasma concentrations of branched-chain amino acids and their corresponding branched-chain alpha-keto acids and branched-chain alpha-hydroxy acids. alpha-Hydroxy acids were more easily excreted in the urine than alpha-keto acids and amino acids. Our studies on urinary organic acids supported the existence of minor metabolic pathways of branched-chain alpha-keto acids, although they were not thought to be important in eliminating accumulated alpha-keto acids. Urinary excretion of succinic acid and alpha-ketoglutaric acid, which are components of the citric acid cycle, increased transiently during the patient's convalescence. The cerebrospinal fluid/plasma ratios for branched-chain amino acids, alpha-keto acids, and alpha-hydroxy acids were very high before the transfusions and decreased after improvement. The cerebrospinal fluid/plasma ratios for 5-carbon acids, alpha-ketoisovaleric acid and alpha-hydroxyisovaleric acid were much higher than for other branched-chain acids not only in the patient but also in normal controls. Cerebrospinal fluid levels of alpha-ketoisocaproic acid and alpha-hydroxyisovaleric acid were as high as 1 mmol/l in our patient.

A familial progressive neurodegenerative disease with 2-oxoglutaric aciduria

A boy and a girl born to a consanguineous Tunisian couple are suffering from a slowly progressive nervous disorder. Initially they both had normal psychomotor development with acquisition of gait and speech. First symptoms in the boy were athetoid movements during the second year of life. He later lost all motor and language skills and developed muscular rigidity and intention tremor. At the age of five years, he was completely bedridden while he appeared mentally much less affected. His younger sister followed a similar course. The major specific abnormality detected was a strikingly elevated excretion of 2-oxoglutaric acid, which was identified by gas liquid chromatography, mass spectrometry, and enzymatic analysis. 2-oxoglutarate dehydrogenase activity in homogenates of cultured skin fibroblasts was reduced to about 25% of control values in both children. Although the pathogenetic mechanisms leading to brain damage remain obscure, the finding strongly suggest an autosomal recessive neurometabolic disease with predominant involvement of the extrapyramidal system.

Congenital lactic acidosis, alpha-ketoglutaric aciduria and variant form of maple syrup urine disease due to a single enzyme defect: dihydrolipoyl dehydrogenase deficiency

A 6-month-old girl with vomiting, hypotonia and motor retardation was found to have elevated blood lactate, pyruvate, and branched chain amino acids associated with ketoglutaric aciduria. The combination of a congenital lactic acidosis with a variant form of maple syrup urine disease and ketoglutaric aciduria suggested a defect of a single component, common to pyruvate dehydrogenase, to branched chain ketoacid dehydrogenase, and to alpha-ketoglutarate dehydrogenase. Dihydrolipoyl dehydrogenase is the common component (E3). The three enzyme activities and the E3 component activity were found to be reduced in liver and cultured fibroblasts, thus confirming that a single defect of this component can result in a multiple deficiency involving several oxidative decarboxylation reactions.

Tumor host relations. VI. Is alpha-ketoglutarate a tumor marker? Association with tumor extent in humans--correlation with tumor size in rats

A 4-year survey is presented on the alpha-ketoglutarate (KG) values in whole blood of 200 patients with malignant neoplasms mainly of the gastrointestinal tract and the female breast. A group of patients with benign surgical diseases served as control. KG showed an association with the extent of the primary tumor classified according to the TNM-scheme. The percentages of single values above the 2s-range of the control were as follows: T2: 18%,T3: 41%, and T4: 64%. The mean value of KG had highly significantly increased already in stage T2 as compared to the control group. Rats bearing the Yoshida sarcoma showed a significant correlation between the tumor size and the daily excretion of KG into urine during the early stage of tumor growth. The results suggested that KG cannot be regarded as an early tumor marker in humans, but may be of some value as an aid for the differential diagnosis in advanced tumor stages.

Studies on alpha-ketoglutaric aciduria in type I glycogenosis

Urinary excretion of the organic acids in patients with type I and III glycogenosis was investigated. In all patients with type I glycogenosis, urinary alpha-ketoglutarate concentration ws about 10 times the normal value. alpha-Ketoglutaric aciduria was not improved by the acute or prolonged administration of a large dose of factors for pyruvate- and alpha-ketoglutarate dehydrogenase complex. On the other hand, the level of alpha-ketoglutarate in the urine from type I patients decreased in conjunction with the decrease of plasma lactate and pyruvate concentration after repeated oral glucose loading. Oral citrate loading brought an increased excretion of alpha-ketoglutarate in type I glycogenosis. It is possible that alpha-ketoglutarate dehydrogenase in the rate-limiting step in tricarboxylic acid cycle and in patients with glycogenosis type I, the excessive excretion of alpha-ketoglutarate may be caused by the limited activity of alpha-ketoglutarate dehydrogenase with excessive substrate.

Tumor host relations. V. Nitrogen metabolism in Yoshida sarcoma-bearing rats. Reduction of growth rate and increase of survival time by administration of physiological doses of branched-chain amino acids

The continuous administration of physiological doses of the branched-chain amino acids leucine, isoleucine, and valine (Leu-Ile-Val) to Yoshida sarcoma-bearing rats caused a significant increase in the survival time by 32% and a significant reduction of tumor size after 3 weeks of growth by 33%. The shift of the nitrogen balance to negative values during the cachectic stage was delayed but not prevented. On the average, less nitrogen (-47 mg/day) were lost by Leu-Ile-Val treated rats compared with untreated tumor-bearing animals (-91 mg N/day). It appeared that Leu-Ile-Val increased the synthesis of carcass proteins, while it left the proteolysis rate unchanged, since the excretion of urea and creatinine was unaffected by these amino acids. The daily excretion of alpha-ketoglutarate, which is correlated with tumor size during the early stage of growth, was decreased during the first 2 weeks by Leu-Ile-Val, but remained for a longer period on a high level than in untreated tumor bearers. The results point to an improvement of the metabolic resistance against carcass protein depletion of the tumor-bearing host by the administration of branched-chain amino acids.

L-2-Hydroxyglutaric aciduria: an inborn error of metabolism?

A 5-year-old boy, excreting large amounts of 2-hydroxyglutaric acid in the urine (3.3-7.6 mmol/l), is described. The patient presented with psychomotor retardation and dystrophy. His skeletal age was delayed. The EEG was not well differentiated; it resembled that observed in 2-year-old children. There was a severe anaemia, which reacted well to iron supplements. The 2-hydroxyglutaric acid was found to have the L-configuration, as analysed by capillary gas chromatography of the O-acetylated di-(-)-2-butyl ester derivative. The relation of L-2-hydroxyglutarate excretion to known metabolic pathways is discussed.

Urinary dicarboxylic acids in patients receiving lithium or rubidium salts

Lithium salts administered in therapeutic doses to four subjects who were kept on controlled diets increased up to fivefold the urinary output of some dicarboxylic acids. Some of the acids affected are intermediates in the tricarboxylic acid cycle, others are chemically similar but not directly related in metabolic terms. This is probably a direct effect on renal transport. Rubidium salts increased urinary 2-oxoglutarate output and blood 2-oxoglutarate levels, probably by some action on intermediary metabolism.

Studies on a patient with in vivo evidence of type I glycogenosis and normal enzyme activities in vitro

Biochemical and clinical studies on a patient with hepatic glycogen storage disease are reported. The patient showed many of the clinical and biochemical features of type I glycogenosis (glucose-6-phosphatase deficiency), but had normal activities of the following enzymes in liver tissue: glucose-6-phosphatase (EC3.1.3.9); amylo-1,6-glucosidase (EC3.2.1.33); glycogen phosphorylase (EC2.4.1.1); fructose-1,6-diphosphatase (EC3.1.3.11). The urinary excretion of 2-oxoglutaric acid was greatly increased in this patient and in a case of enzymologically proven type I glycogenosis. Abnormal 2-oxoglutaric aciduria has not been previously reported in the glycogen storage diseases. The results are discussed in relation to the possible nature of the underlying biochemical defect in patients of this type.

High-performance liquid chromatography of pyruvic and alpha-ketoglutaric acids and its application to urine samples

Pyruvic and alpha-ketoglutaric acids were quantitatively and rapidly converted to quinoxalones by a new method, to enhance their detectability in the ultraviolet. The quinoxalones were separated by reversed-phase chromatography with use of 10 micronm particles packed in a 30-cm (length) column. An aqueous solution of ammonium acetate and methanol was used for linear gradient elution. The urinary excretion of pyruvic and alpha-ketoglutaric acids by normal individuals, diabetic patients, and patients with renal dysfunction was determined.

Urinary organic acid profiles of Reye's syndrome patients

The status of mitochondrial functioning in Reye's syndrome was assessed by comparing organic acid profiles from nine pathological urines with those from normal urines. It was found that Reye's syndrome urines have a normal content of succinic, oxaloacetic, aconitic, and citric acids suggesting that the enzymes of the acid cycle are functional. Elevated pyruvate and depressed alpha-ketoglutarate levels were observed. Abnormal urinary constituents detected were salicylic and adipic acids. Presence of the latter indicates that the enzymes of fatty acid beta-oxidation are functional.