Simultaneous metabolic profile studies of three patients with fatal infantile mitochondrial myopathy-de Toni-Fanconi-Debré syndrome by GC/MS

Prof. Dr. Giovanni De Toni-Editorial for the Commemoration of a Pediatric Luminary

Living in Liguria, acknowledging that the sea may be a metaphor for the human condition is not difficult [...].

Focus on Mitochondrial Respiratory Chain: Potential Therapeutic Target for Chronic Renal Failure

The function of the respiratory chain is closely associated with kidney function, and the dysfunction of the respiratory chain is a primary pathophysiological change in chronic kidney failure. The incidence of chronic kidney failure caused by defects in respiratory-chain-related genes has frequently been overlooked. Correcting abnormal metabolic reprogramming, rescuing the "toxic respiratory chain", and targeting the clearance of mitochondrial reactive oxygen species are potential therapies for treating chronic kidney failure. These treatments have shown promising results in slowing fibrosis and inflammation progression and improving kidney function in various animal models of chronic kidney failure and patients with chronic kidney disease (CKD). The mitochondrial respiratory chain is a key target worthy of attention in the treatment of chronic kidney failure. This review integrated research related to the mitochondrial respiratory chain and chronic kidney failure, primarily elucidating the pathological status of the mitochondrial respiratory chain in chronic kidney failure and potential therapeutic drugs. It provided new ideas for the treatment of kidney failure and promoted the development of drugs targeting the mitochondrial respiratory chain.

[Renal involvement in mitochondrial cytopathies]

Mitochondrial disorders are genetic defects of oxidative phosphorylation. Oxidative phosphorylation takes place in the mitochondrial inner membrane and consists of the oxidation of fuel molecules by oxygen and the concomitant energy transduction into ATP. The mitochondrial respiratory chain is a complex metabolic pathway. It is made of approximately 100 polypeptides, most of which are encoded in the nucleus whereas 13 are encoded in the mitochondria. Mitochondrial DNA is maternally inherited and its mutations are transmitted by the mother. During cell division, mitochondria are randomly partitioned in daughter cells. Therefore, in case normal and mutant DNA are present in the mother's cells, some lineage may have only mutant mitochondrial DNA or normal mitochondrial DNA while others may have both mutant and normal DNA, a condition named heteroplasmy. Renal involvement in mitochondrial cytopathies is rare. Patients most often present with a more or less complete de Toni-Debré-Fanconi syndrome. A few patients present with a nephrotic syndrome or with chronic tubulointerstitial nephritis. The investigation of patients with mitochondrial disorders include metabolic screening for abnormal oxidoreduction status in plasma, investigation of the mitochondrial respiratory chain, including polarographic and spectrophotometric studies, histopathologic studies and genetic studies.

Galactose metabolism by the mouse with galactose-1-phosphate uridyltransferase deficiency

The ability of mice deficient in galactose-1-phosphate uridyltransferase (GALT) to metabolize galactose was determined in animals weaned to a mouse chow diet for a 4-wk period. When given [14C]galactose intraperitoneally, these animals slowly oxidized the sugar, excreting only 5.5% of the dose as 14CO2 in 4 h, whereas normal animals excreted 39.9%. These results mimic those seen in human galactosemic patients given isotopic galactose. When given 10 micromol of [1-13C]galactose, normal animals excrete small amounts of labeled galactose and galactonate but no galactitol in urine whereas GALT-deficient mice excrete significant amounts of all of these as labeled compounds in urine. When challenged with galactose, only about 20% of the dose is excreted in urine, and even on the chow diet, significant amounts of galactose, galactonate, and galactitol are excreted in urine. These compounds are also found to be present in liver, kidney, and brain, except that galactonate is not found in brain. Galactose-1-phosphate accumulates in red blood cells to levels found in humans exposed to large amounts of galactose, and galactose-1-phosphate is found in increased amounts in liver, kidney, and brain of GALT-deficient animals. There was no difference in the hepatic concentration of uridine diphosphate galactose and uridine diphosphate glucose between normal and GALT-deficient mice. The explanation for the presence of galactose and its conversion products in tissues and urine of affected mice appears to be related to the presence of approximately 1.75% of galactose-containing carbohydrates in the chow, which becomes bioavailable to mice. Despite the presence of galactose and its metabolites in tissues and urine and impaired ability to oxidize the sugar, the GALT-deficient animals are indistinguishable from normal animals and do not exhibit the phenotype of humans with GALT-deficiency galactosemia.

Urine and plasma galactitol in patients with galactose-1-phosphate uridyltransferase deficiency galactosemia

Urinary excretion of galactitol was determined in 95 normals (N/N), 67 galactosemic (G/G), and 39 compound heterozygotes for the Duarte and galactosemia genotype (D/G). Galactitol excretion is age-dependent in both normal individuals and patients with classic galactosemia on lactose-restricted diets. In galactosemic patients who are homozygous for the Q188R mutation, urinary galactitol levels were fivefold to 10-fold higher than those of normal subjects of comparable age. All but a few patients with classic galactosemia with the Q188R mutation and another mutant G allele had urinary excretion comparable to the Q188R homozygous patients. African-American galactosemic patients with the S135L mutation of the galactose-1-phosphate uridyltransferase (GALT) gene also excreted abnormal quantities of galactitol. Most subjects with a Duarte allele and a G allele excrete normal amounts of the sugar alcohol. There is a correlation between galactitol excretion and red blood cell (RBC) galactose-1-phosphate (gal-1-P). Plasma galactitol was also elevated in galactosemic patients (3.4 to 23.2 micromol/L; undetectable in normal individuals). In contrast to the decrease in urinary galactitol with age, plasma levels remain in a narrow concentration range with no significant difference with age. Urine and plasma galactitol distinguish galactosemic patients from normals. In addition, urinary galactitol excretion may be an important parameter for the assessment of steady-state galactose metabolism in galactosemia.

Pilot study of gas chromatographic-mass spectrometric screening of newborn urine for inborn errors of metabolism after treatment with urease

Gas chromatographic-mass spectrometric (GC-MS) techniques for urinary organic acid profiling have been applied to high-risk screening for a wide range of diseases, mainly for inborn errors of metabolism (IEM), rather than to low-risk screening or mass screening. Using a simplified procedure with urease-pretreatment and the GC-MS technique, which allows simultaneous determination of organic acids, amino acids, sugars and sugar acids, we performed a pilot study of the application of this procedure to neonatal urine screening for 22 IEM. Out of 16,246 newborns screened, 11 cases of metabolic disorders were chemically diagnosed: two each of methylmalonic aciduria and glyceroluria, four of cystinuria, and one each of Hartnup disease, citrullinemia and alpha-aminoadipic aciduria/alpha-ketoadipic aciduria. The incidence of IEM was thus one per 1477, which was higher than the one per 3000 obtained in the USA in a study targeting amino acids and acylcarnitines in newborn blood spots by tandem mass spectrometry. Also, 227 cases were found to have transient metabolic abnormalities: 108 cases with neonatal tyrosinuria, 99 cases with neonatal galactosuria, and 20 cases with other transient metabolic disorders. Two hundred and thirty-eight cases out of 16,246 neonates (approximately 1/68) were thus diagnosed using this procedure as having either persistent or transient metabolic abnormalities.

Gas chromatographic-mass spectrometric analysis of urinary sugar and sugar alcohols during pregnancy

A refined and simplified method has been developed for the simultaneous analysis of urinary sugar and sugar alcohols after urease treatment by using capillary gas chromatography-mass spectrometry (GC-MS). Since carbohydrate metabolism during pregnancy is considered to be diabetogenic, our interest has been concentrated on understanding the mechanism of the metabolic deviation by assessing the glucose excursion and glucose fluxes. The present study suggests that changes of the levels of glucose, sorbitol, fructose, myo-inositol, and 1,5-anhydro-D-glucitol (1,5-AG) may reflect a mild alteration in carbohydrate metabolism that goes undetected by conventional diabetic indicators.

Transitional cell carcinoma of the renal pelvis with vena caval tumor thrombus

We report a case of transitional cell carcinoma of the renal pelvis with vena caval tumor thrombus. To our knowledge only 14 cases of transitional cell carcinoma of the renal pelvis protruding into the vena cava have been reported. The literature regarding these cases is reviewed, and the differential diagnosis of this tumor from renal cell carcinoma is discussed.

Family study of 2,8-dihydroxyadenine stone formation: report of two cases of a compound heterozygote for adenine phosphoribosyltransferase deficiency (APRT*J/APRT*Q0)

The family members of 2 formers of 2,8-dihydroxyadenine stones were examined for history, adenine phosphoribosyltransferase (APRT) activity, genotype, urinary sediment, and urinary constituents. The patients' father showed a genotype of APRT*1/APRT*Q0, and their mother showed APRT*1/APRT*J. Patients 1 and 2 were compound heterozygotes for adenine phosphoribosyltransferase deficiency (APRT*J/APRT*Q0), and APRT activities were 4.5% and 4.0% of normal, respectively. 2,8-Dihydroxyadenine crystals could be seen in the urinary sediment. Treatment with allopurinol completely stopped new stone formation for 5 years in patient 1.

A new chemical diagnostic method for inborn errors of metabolism by mass spectrometry-rapid, practical, and simultaneous urinary metabolites analysis

In most developed countries, neonatal mass screening programs for the early diagnosis of inborn errors of metabolism (IEM) have been implemented and have been found to be effective for the prevention or significant reduction of clinical symptoms such as mental retardation. These programs rely primarily on simple bacterial inhibition assays (the "Guthrie tests"). We developed a new method for screening IEM using GC/MS, which enables accurate chemical diagnoses through urinary analyses with a simple practical procedure. The urine sample preparation for GC/MS takes one hour for one sample or three hours for a batch of 30 samples (will be fully automated shortly), and the following GC/MS measurement is completed within 15 min per sample. This method allows the simultaneous analyses of amino acids, organic acids, sugars, sugar alcohols, sugar acids, and nucleic acid bases. Therefore, a large number of metabolic disorders can be simultaneously tested by this chemical diagnostic procedure. This method is quite comprehensive and different from conventional GC/MS organic acidemia screening procedures, which are not well-suited to detect metabolic disorders except organic acidurias. Sample preparation includes urease treatment, deproteinization, and derivatization. The method has also been applied to neonate urine specimens that are absorbed into filter paper. The air-dried samples were mailed to the analytical laboratory and eluted with water. The eluate (0.1 mL) was incubated with urease, followed by deproteinization with alcohol, evaporation to dryness of the supernatant, and trimethylsilylation; the samples were applied to GC/MS. A pilot study of the application of this diagnostic procedure to the neonatal mass screening of 22 disorders was started in Japan on February 1, 1995 in cooperation with four medical institutes. This program is supported by the Japanese Society for Biomedical Mass Spectrometry and the Japanese Mass Screening Society. The initial twenty-two target metabolic diseases are: methylmalonic acidemia; propionic acidemia; isovaleric acidemia; maple syrup urine disease; β-ketothiolase deficiency; galactosemia; phenylketonuria; hyperphenylalaninemia; homocystinuria; alkaptonuria; multiple carboxylase deficiency; nonketotic hyperglycinemia; lysinuria; cystinuria; tyrosinemia; glutaric aciduria type I; β-hydroxy-β-methylglutaric acidemia; β-methylcrotonylglycinuria; α-aminoadipic-α-ketoadipic aciduria; ornitine transcarbamylase deficiency (four urea cycle disorders can be screened); glutaric aciduria type II; and neuroblastoma. Neuroblastoma is not an IEM, and is examined at ca. 6 months of age. The twenty-two target diseases will be reconsidered during the pilot study. An accurate chemical diagnosis and hence early treatment of not only organic acidemias but also amino acidemias, and sugar-, polyol-, and nucleic acid base-accumulating metabolic disorders can be made at a very early stage of life. This procedure is also applicable to metabolic profiling of other body fluids that are potentially informative for the study and characterization of a wide range of inherited and acquired metabolic disorders. © 1997 John Wiley & Sons, Inc.