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Schizophrenia is a severe mental disorder that affects 0.5-1% of the population worldwide. Current diagnostic methods are based on psychiatric interviews, which are subjective in nature. The lack of disease biomarkers to support objective laboratory tests has been a long-standing bottleneck in the clinical diagnosis and evaluation of schizophrenia. Here we report a global metabolic profiling study involving 112 schizophrenic patients and 110 healthy subjects, who were divided into a training set and a test set, designed to identify metabolite markers. A panel of serum markers consisting of glycerate, eicosenoic acid, β-hydroxybutyrate, pyruvate and cystine was identified as an effective diagnostic tool, achieving an area under the receiver operating characteristic curve (AUC) of 0.945 in the training samples (62 patients and 62 controls) and 0.895 in the test samples (50 patients and 48 controls). Furthermore, a composite panel by the addition of urine β-hydroxybutyrate to the serum panel achieved a more satisfactory accuracy, which reached an AUC of 1 in both the training set and the test set. Multiple fatty acids and ketone bodies were found significantly (P<0.01) elevated in both the serum and urine of patients, suggesting an upregulated fatty acid catabolism, presumably resulting from an insufficiency of glucose supply in the brains of schizophrenia patients.

Objective: To observe abnormal metabolic changes caused by ischemic cerebral apoplexy and the regulating action of Tongsaimai pellets on abnormal metabolism by analyzing the change of small molecules in plasma of ischemic cerebral apoplexy rat. To find the potential biomarkers, and to explore metabolic mechanisms of Tongsaimai pellets., Method: Rat models of middle cerebral artery occlusion was established with electric coagulation, and rats were divided into 4 groups, model group, sham-operation group, Tongsaimai pellets group and positive control group. Tongsaimai pellets and positive control group were orally administrated by 13.2 g x kg(-1) x d(-1) of crude drugs and 32 mg x kg(-1) x d(-1) of Nimodipine respectively, m odel and sham-operation group by equal volume of distilled water for a week. Plasma of model and sham-operation group were collected, and plasma of Tongsaimai pellets and positive control group were collected on the 1st, 3rd , 7th day after administration. Endogenous metabolites of four groups were determined with GC-MS. Partial least squares discriminant analysis (PLS-DA) was applied to analyze multivariate data and set up model, and T-test was used in significant statistical analysis., Result: Compared with sham-operation group rats, pyruvic acid, taurine and hydroxyproline obviously increased in model group rats, while lactic acid, glyceric acid, aminomalonic acid, fructose, tryptophan and leucine significantly decreased, so these metabolites were potential metabolic biomarkers. These endogenous metabolites except taurine got restoration in Tongsaimai group rats., Conclusion: Abnormal metabolite level in plasma can be certainly recovered by Tongsaimai pellets, and the treatment of Tongsaimai pellets can be connected with the regulation of related metabolic pathways.

Deficiency of human glycerate kinase leads to D-glycerate acidemia/D-glyceric aciduria. Through PCR cloning assisted by in silico approach, we isolated the human glycerate kinase genes--Glycerate Kinase 1 (GLYCTK1) and its alternatively splicing variant--Glycerate Kinase 2 (GLYCTK2), which might be associated with D-glycerate acidemia/D-glyceric aciduria. The locus of GLYCTK gene is mapped to 3p21. PCR amplification in seventeen human tissue cDNAs revealed that both GLYCTK1 and GLYCTK2 are expressed widely almost in all these tissues. The expression of mouse Glyctk in various tissues was demonstrated by in situ hybridization. Both GLYCTK1 and GLYCTK2 proteins are localized in cytosol, and GLYCTK2 proteins are specifically localized in mitochondria. Present results revealed the characteristic expression pattern of murine Glyctk in neural system, skeleton muscle, supporting that glycerate kinase is implicated in D-glycerate acidemia/D-glyceric aciduria.

Oxalate retention occurs in end-stage renal failure. Regular dialysis treatment does not prevent progressive accumulation of oxalate in cases of ESRF due to primary hyperoxaluria (PH), whereas such accumulation seldom seems to occur in oxalosis-unrelated ESRF. To elucidate this issue we have measured the bony content of oxalate on biopsies of the iliac crest taken from 32 uremic patients, 7 of them with ESRF associated with PH1 (6 cases) or PH2 (1 case). Ten subjects with normal renal function and no evidence of metabolic bone disease were taken as controls. Only trace amounts levels of oxalate were detected in normal subjects and oxalate to phosphate ratio was below 3:10,000. Non-PH dialyzed patients exhibited fivefold increases in oxalate levels, which rose to 5.1 +/- 3.6 mumol/g bony tissue. Calcium oxalate was estimated to represent 0.18% of the hydroxyapatite content of bone. Oxalate amounts were neither related to pre-dialysis plasma levels of oxalate, nor with duration of dialysis treatment, suggesting that accumulation was not progressive disorder. Oxalate levels were slightly higher in patients with a low turnover osteodystrophy compared to those with a high turnover pattern. Dialyzed patients with PH had remarkable increases in oxalate levels, which ranged between 14.8 and 907 mumol/g bony tissue. Oxalate deposition appeared to be progressive in that oxalate levels were significantly related to time on dialysis. In three patients calcium oxalate was a significant fraction of the mineralized bone. The occurrence of calcium oxalate crystals affected the histomorphometric patterns, that were featured by an increase in resorptive areas and a decrease in bone formation rate.(ABSTRACT TRUNCATED AT 250 WORDS)

We describe a liquid chromatographic technique to determine L-glycerate in body fluids. The method is based on the derivatisation of the L-glycerate by incubation with lactate dehydrogenase and nicotinamide-adenine dinucleotide in the presence of phenylhydrazine. Oxidation of L-glycerate forms beta-hydroxypyruvate which is converted in turn into the related phenylhydrazone. The UV-absorbing derivative is determined using reversed-phase high performance liquid chromatography. The sensitivity was 5 mumol/l and 50 microliters of sample were required. The imprecision relative standard deviation was 4.5% and the recovery was 96.5 +/- 6.8% for L-glycerate in plasma. L-Glycerate concentrations in urine and plasma were less than 5 mumol/l in both normal individuals and patients with glycolic aciduria. In a patient with systemic oxalosis and normal plasma glycolate, plasma L-glyceric acid was 887 mumol/l.

To exploit the well documented effect of 2,3-diphosphoglyceric acid (2,3-DPG) in enhancing oxygen delivery by human erythrocytes, we have investigated whether the DPG synthase/phosphatase enzyme system can be targeted to increase DPG levels in the cell. The hydrolytic activity (phosphatase) of the DPG metabolizing enzyme complex exhibits a marked dependence on a physiological effector, 2-phosphoglycolate. Little phosphatase activity is detected in the absence of this activator irrespective of the concentrations of the substrate. The phosphoglycolate-dependent phosphatase activity is competitively inhibited by a glycolytic intermediate, 3-phosphoglyceric acid (3-PGA). The 3-PGA inhibition persists when the 2,3-DPG concentration is raised to saturation level. In contrast, 3-PGA enhances the DPG synthase activity in a dose-dependent manner. In intact red cells, one-half of the cellular DPG content is depleted after 6 hr at 37 degrees C in glucose-free medium. The rate of 2,3-DPG degradation is accelerated when the cellular level of phosphoglycolate is increased by incubation with exogenous glycolate. Together, these results indicate that 2,3-DPG content in erythrocytes can be directly regulated through modulation of phosphatase/synthase activities. In support of this notion, a pyruvate kinase inhibitor, L-alanine, increases by 2-fold the cellular 3-PGA level. This is accompanied by a significant increase (30%) in 2,3-DPG content in human red blood cells. It is postulated that the DPG-promoting action of 3-PGA is mediated through simultaneous phosphatase inhibition and synthase activation. Furthermore, as a result of increased DPG accumulation, the oxygen-hemoglobin dissociation curve in L-alanine-treated cells is rightward shifted by 2.5 torr.

We have found that glycolysis in human red blood cells under the hypoxic conditions found at high altitudes is connected with changes in enzyme activities and levels of various metabolic intermediates. The sensitivity of the four kinases to hypoxia results in 1) glycolytic hyperactivity leading to a higher intracellular energy state, and 2) accumulation of 2-3 DPG, whose role in the adaptation of red blood cell respiration to high altitude has been shown by previous research. PEP, 3PG , and G6P appear to be the main regulating intermediates in glycolysis in this system. The reason for the very large increase in G1- 6DP is still not clear.

A mentally retarded boy exhibiting both hyper-D-glyceric acidemia and hyperglycinemia and in whom a deficiency of D-glycerate dehydrogenase had previously been demonstrated was investigated to elucidate the ethiology of the glycine accumulation and its relationship to the D-glyceric acid accumulation. It was found that a positive correlation existed between excretion of D-glyceric acid and glycine (coefficient of correlation: r = 0.62, P < 0.001), that part of the IV injected [14C]glycine was metabolized to D-glyceric acid whereas no [14C]glyceric acid was metabolized to glycine, and that the in vivo degradation of IV injected [14C]glycine to 14CO2 was diminished. Measurement of glycine cleavage activity in autoptic liver tissue from the patient showed only 10% of normal activity. It is argued that this diminished activity could be caused by an endogenous inhibitor. D-glyceric acid is demonstrated not to possess such an inhibitory effect. Based on the finding of increased urinary excretion of both free and conjugated isobutyric acid, 2-methylbutyric acid, and isovaleric acid, it is hypothesized that the diminished glycine cleavage activity might be due, at least partially, to inhibition by 2-methylbutyryl-CoA and isobutyryl-CoA, two compounds that are known to inhibit the glycine cleavage system.

Studies of a mentally retarded boy, clinically suffering from nonketotic hyperglycinemia, are reported. Using combined gas chromatography-mass spectrometry, enzyme specificity studies, and spectropolariometry D-glyceric acid in extremely elevated concentrations was demonstrated in both serum and urine (serum: 1.0-1.3 mmol/liter, urine: 33-187 mmol/liter). Hydroxypyruvic acid was not detectable in urine from this boy using a gas chromatographic method with a limit of detection of 0.3 mmol/liter. Enzyme assays of D-glyceric dehydrogenase on blood leukocytes demonstrated significantly lower activity in the patient compared with five normal children.

The separation of the enantiomers of lactic and glyceric acids can be achieved by capillary gas chromatography on SP-1000 using the corresponding O-acetylated methyl esters. The structures of the derivatives were proved by proton magnetic resonance spectroscopy and mass spectrometry. The method has been used for the determination of the absolute configuration of lactic and glyceric acids isolated from serum and urine from different patients.

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 case of pyruvate kinase (PK) deficiency is described in which the diagnosis was aided by measurement of the 3-phosphoglycerate (3PG) concentration. Review of the literature on the levels of red cell metabolites in 52 families with PK deficiency confirmed that a rise in 3PG is a valuable indicator of a functional deficiency of PK. Estimation of 3PG is relatively easy (and accurate). Furthermore, reticulocytosis, which sometimes makes the diagnosis of PK deficiency more difficult, has minimal effect on the level of 3PG in comparison with all other glycolytic intermediates or PK activity.

A mentally retarded girl with epileptic seizures is described. Urinary organic acid screening revealed a massive excretion of glyceric acid, a normally barely detectable metabolite. Hyperglycinemia was not observed. Capillary gas chromatography of the O-acetylated (-)-menthyl ester of urinary glyceric acid showed the substance to have the D-configuration. The urinary D-glycerate excretion remained unaltered after an oral load with 200 mg/kg L-serine, but oral loading with fructose (1 g/kg) or dihydroxyacetone (1 g/kg) caused a sharp increase of the D-glycerate excretion. Treatment with a diet moderately restricted in fructose led to some clinical improvement as judged by subjective criteria. The metabolic lesion is thought to be located at some step of the fructose catabolic pathway, possibly at the level of hepatic triokinase deficiency.

The glycine uptake in cultured fibroblasts was studied in three children with non-ketotic hyperglycinaemia, one child with D-glyceric acidaemia and hyperglycinaemia and in six normal children, using an improved assay system giving individual protein correction. It was shown that all hyperglycinaemic children had normal uptake rates and kinetic characteristics similar to the controls.

A patient is described with glyceric acidemia and glyceric aciduria. The main clinical problems in infancy were severe metabolic acidosis and failure to thrive. The patient needs permanent treatment with bicarbonate. Hyperglycinemia, as described in the first case discovered elsewhere, was not present. The glyceric acid was found to have the D-configuration, as analyzed by capillary gas chromatography of its di-O-acetyl-l-menthyl ester. The abnormality may result from a defect in serine metabolism.

Red cell glycolytic intermediates and adenosinetriphosphate were evaluated in term infants from birth to on year of age and compared to values obtained from normal adults and subjects wit a population of a similar mean cell age. The concentration of glycolytic intermediates, with the exception of phosphoenolypyruvate were elevated at birth when compared to normal subjects, consistent with a young mean red cell population. The mean levels of red cell glucose-6-phosphate, fructose-6-phosphate, and "total triose phosphate" were elevated on days 1 and 4 of life when compared to both red cells from normal adults and subjects with a similar young mean red cell age. Glucose-6-phosphate steadily increased in concentration, peaked at 3 to 4 wk of age, and then progressively decreased in value. Total triose phosphate declined to a mildly elevated concentration by 3 to 4 wk of age. The mean concentrations of 2,3-diphosphoglycerate and adenosine triphosphate were normal on day 1, increased on day 4, and then declined by 3 to 4 wk to normal values, until 5 to 6 months when both increased. The mean phosphoenolpyruvate concentration was decreased on day 1 of age when compared to red cells of a similar mean age, but this decrease was not significant (P greater than 0.05). The mean concentrations of 3-phosphoglycerate increased at 3 to 4 wk of age and remained elevated for cell age at 11 to 12 months but this increase was no statistically significant (P greater than 0.05). 3-Phosphoglycerate levels did not change significantly throughout the first year of life. At one year of age, all red glycolytic intermediates and adenosine triphosphate were elevated when compared to red cells from normal adults, but were comparable to those observed in subjects with a red cell population of a similar mean cell age, consistent with the persistence of a young red cell population throughout the first year of life.

The hypothesis that human red cells contain activity of ribulose-1,5-diphosphate (Ru-1,5-P2) oxygenase, an enzyme that catalyzes the synthesis of phosphoglycolate, was examined. The putative Ru-1,5-P2 oxygenase was partially purified from human red cells using DE-52 chromatography and (NH4)2SO4 fractionation by monitoring Ru-1,5-P2-dependent 3-phosphoglycerate formation. The synthesis of [32P]phosphoglycolate from [1-32P]Ru-1,5-P2 was attempted in the presence of the partially purified preparation of the provisional Ru-1,5-P2 oxygenase. There was no formation of radioactive phosphoglycolate even under 100% oxygen gas, indicating the absence of this enzyme activity in human red cells. Together with our previous report that glycolate kinase in human red cells is not responsible for the synthesis of phosphoglycolate in vivo, these studies raise the questions whether there is actually phosphoglycolate in red cells as well as whether novel pathways for its synthesis exist.

The clinical and laboratory findings in a 2 1/2-year-old boy with non-ketotic hyperglycinaemia are reported. Except for a somewhat impaired liver function there was a picture similar to the cases previously reported in the literature. The patient deviated from the classical description, however, in the excretion of large amounts of D-glyceric acid in the urine. The same compound was also repeatedly found in the serum. It is suggested that the large amounts of glycine found in various body fluids are secondary to a hitherto undescribed enzymatic defect in the degradation of D-glyceric acid.

Red cell glycolytic intermediates and ATP were evaluated in 47 appropriate for gestational age preterm infants on the 1st day of life who were divided into three groups on the basis of gestational age: 28-30, 31-33, and 34-36 wk. The results were compared to those previously obtained in term infants. The concentrations of glucose-6-phosphate, total triose phosphates, and ATP were significantly higher than in term infants but appeared to be appropriately elevated for the young mean age of the red cell population. The concentration of red cell 2,3-diphosphoglycerate (2,3-DPG) was significantly decreased when compared to term infants and was lowest at 28-30 wk gestation. The content of red cell 3-phosphoglycerate was increased in term infants and was inappropriately elevated for the age of the red cell population at 28-30 wk gestation. This pattern of glycolytic intermediates was suggestive of a young red cell population metabolizing at an increased glycolytic rate with increased flow through the phosphoglycerate kinase step rather than the 2,3-DPG bypass in "normal" preterm infants. Two preterm infants of 28-30 wk gestation with low red cell intracellular pH were also evaluated and had markedly decreased concentrations of red cell 2,3-DPG and ATP and all phosphorylated intermediates distal to the phosphofructokinase reaction, indicative of a cross-over at the phosphofructokinase step secondary to acidosis.(ABSTRACT TRUNCATED AT 250 WORDS)

A biphasic thyroid hormonal effect has been shown on 2,3-diphosphoglyceric acid synthesis in a crude enzyme, hemoglobin-free preparation from normal human erythrocytes.