High-Throughput Metabolomics for Discovering Potential Metabolite Biomarkers and Metabolic Mechanism from the APPswe/PS1dE9 Transgenic Model of Alzheimer's Disease.

Alzheimer's disease (AD), a neurodegenerative disorder, is the major form of dementia. As AD is an irreversible disease, it is necessary to focus on earlier intervention. However, the potential biomarkers of preclinical AD are still not clear. In this study, urinary metabolomics based on ultra-high-performance liquid chromatography coupled with quadruple time-of-flight mass spectrometry was performed for delineating the metabolic changes and potential early biomarkers in APPswe/PS1dE9 (APP/PS1) transgenic mice. A total of 24 differentially regulated metabolites were identified when comparing transgenic mice to wild-type mice using multivariate statistical analysis. Among them, 10 metabolites were significantly upregulated and 14 metabolites were downregulated. On the basis of these potential biomarkers, metabolic pathway analysis found that pentose and glucuronate interconversions, glyoxylate and dicarboxylate metabolism, starch and sucrose metabolism, the citrate cycle, tryptophan metabolism, and arginine and proline metabolism were disturbed in APP/PS1 mice. Our study revealed that levels of endogenous metabolites in the urine of APP/PS1 mice changed prior to the emergence of learning and cognitive impairment, which may be associated with abnormal nitric oxide production pathways and metabolic disorders of monoaminergic neurotransmitters. In conclusion, this study showed that metabolomics provides an early indicator of disease occurrence for AD.

Garrod's Croonian Lectures (1908) and the charter 'Inborn Errors of Metabolism': albinism, alkaptonuria, cystinuria, and pentosuria at age 100 in 2008.

Garrod presented his concept of 'the inborn error of metabolism' in the 1908 Croonian Lectures to the Royal College of Physicians (London); he used albinism, alkaptonuria, cystinuria and pentosuria to illustrate. His lectures are perceived today as landmarks in the history of biochemistry, genetics and medicine. Garrod gave evidence for the dynamic nature of metabolism by showing involvement of normal metabolites in normal pathways made variant by Mendelian inheritance. His concepts and evidence were salient primarily among biochemists, controversial among geneticists because biometricians were dominant over Mendelists, and least salient among physicians who were not attracted to rare hereditary 'traits'. In 2008, at the centennial of Garrod's Croonian Lectures, each charter inborn error of metabolism has acquired its own genomic locus, a cloned gene, a repertoire of annotated phenotype-modifying alleles, a gene product with known structure and function, and altered function in the Mendelian variant.

Characterisation of putative pentose-containing conjugates as minor metabolites of 4-bromoaniline present in the urine of rats following intraperitoneal administration.

The metabolic fate of 4-bromoaniline (4-BrA) was investigated following intraperitoneal administration to the rat at 50 mg kg(-1), using high-performance liquid chromatography/time-of-flight tandem mass spectrometry (HPLC/TOF-MS/MS). Up to five metabolites were detected in urine that correspond to isomeric pentose conjugates (possibly ribosides) of a hydroxysulphate of 4-BrA. This identification is supported by further studies where the water used in the reversed-phase solvent system was replaced with deuterated water in order to confirm that the number of exchangeable protons present in the metabolites was consistent with the proposed structures.

Transaldolase deficiency: liver cirrhosis associated with a new inborn error in the pentose phosphate pathway.

This article describes the first patient with a deficiency of transaldolase (TALDO1 [E.C.2.2.1.2]). Clinically, the patient presented with liver cirrhosis and hepatosplenomegaly during early infancy. In urine and plasma, elevated concentrations of ribitol, D-arabitol, and erythritol were found. By incubating the patient's lymphoblasts and erythrocytes with ribose-5-phosphate and subsequently analyzing phosphate sugar metabolites, we discovered a deficiency of transaldolase. Sequence analysis of the transaldolase gene from this patient showed a homozygous deletion of 3 bp. This deletion results in absence of serine at position 171 of the transaldolase protein. This amino acid is invariable between species and is located in a conserved region, indicating its importance for enzyme activity. The detection of this new inborn error of pentose metabolism has implications for the diagnostic workup of liver problems of unknown etiology.

Human L-xylulose reductase variation: family and population studies.

Only one of the two main L-xylulose reductases present in human tissue is deficient in individuals with essential pentosuria (Lane, 1985). The isozyme which is affected by the pentosuria mutation occurs as mitochondrial and cytosolic forms in normal individuals, whereas the other isozyme (which is not affected by the mutation) occurs only in the cytosol. A new assay of red cell L-xylulose reductase activity has facilitated the identification of carriers of the essential pentosuria allele at both family and population levels. Reinvestigation of a Lebanese family in which pentosuria has previously been thought to be dominantly inherited reveals that the condition is recessively inherited in this family as well. A minimum estimate of the frequency of the pentosuria allele in an Ashkenazi-Jewish population, calculated from the apparent heterozygote frequency, is 0.0127. The likelihood of the Ashkenazi and Lebanese pentosuria alleles being the same is discussed.

On the nature of L-xylulose reductase deficiency in essential pentosuria.

Essential pentosuria is the result of a partial deficiency of L-xylulose reductase. Red blood cells of normal individuals have been found to contain two L-xylulose reductases: a major and a minor isozyme. Red cells from pentosurics contain only one isozyme. The residual enzyme of pentosurics and the normal minor isozyme have similar Michaelis constants for L-xylulose and xylitol, similar activity responses to pH, and similar rates of migration when electrophoresed or subjected to ion-exchange chromatography. It is suggested that homozygosity for the pentosuria allele results in the absence of the major isozyme and that the residual isozyme of pentosurics is identical to the minor isozyme of normal individuals.

[Melituric picture in a group of myasthenics]. / Il quadro meliturico in un gruppo di miastenici.

On the ground of preceding researches carried out about myodystrophias, the authors studied the melituric symptomatology in both a group of myasthenic patients and a group of control. The chromatographic analysis and the dosage of some urinary carbohydrates, showed that there are not statistically significant differences between the group of myasthenic patients and that of controls.

Familial incidence of L-xylulosuria.

During a survey for genetic disorders, L-Xylulosuria, an autosomal recessive condition, was found to affect three cousins in an inbred family. There were no clinical symptoms.

Increased urinary excretion of L-xylulose in patients with liver cirrhosis.

The urinary excretions of L-xylulose, xylitol and D-glucarate after the oral administration of glucuronolactone (5 g) were measured in normal healthy persons, patients with diabetes mellitus, acute hepatitis in recovery stage, chronic hepatitis and liver cirrhosis. In normal subjects, the mean value of L-xylulose excretion was 14.6 +/- 1.4 mumol/2 h with a range from 6.5 to 21.8. Marked increase of L-xylulose excretion was observed in cirrhotic patients, the mean value was 97.1 +/- 19.8 with a range from 22.0 to 236.6. Though some cases of acute and chronic hepatitis showed higher values than the normal range, no case exceeded 50 mumol/2 h. The urinary excretion of xylitol in cirrhotic patients was also higher than normal no increase was observed in D-glucarate excretion. The values of L-xylulose excretion in cirrhosis were correlated with the values of serum total bilirubin, albumin, albumin/globulin ratio, lactate dehydrogenase and prothrombin time. These findings indicate that the measurement of L-xylulose in urine after the oral glucuronolactone loading provides a useful tool for evaluation of the severity of liver cirrhosis.