Phenotypic variability, neurological outcome and genetics background of 6-pyruvoyl-tetrahydropterin synthase deficiency.

This study aimed to investigate the clinical variability and factors implied in the outcome of 6-pyruvoyl-tetrahydropterin synthase deficiency (PTPSd). Biochemical and clinical phenotype, treatment variables, and 6-pyruvoyl-tetrahydropterin synthase (PTS) genotype, were explored retrospectively in 19 Italian patients (12 males and 7 females, aged 4 months to 33 years). According to the level of biogenic amines in cerebrospinal fluid (CSF) at the diagnosis, the patients were classified as mild (6) (normal level) or severe (13) (abnormal low level) form (MF and SF, respectively). Blood Phe ranged from 151 to 1053 micromol/l in MF (mean +/- SD: 698 +/- 403) and 342-2120 micromol/l in SF (mean +/- SD: 1175 +/- 517) (p = 0.063). Patients with MF showed a normal neurological development (a transient dystonia was detected in one), while all SF patients except one presented with severe neurological impairment and only four had a normal neurological development. The outcome of the SF was influenced by the precocity of the treatment. Serial CSF examinations revealed a decline of 5-hydroxyindolacetic acid in MFs and an incomplete restoration of neurotransmitters in SFs: neither obviously affected the prognosis. PTS gene analysis detected 17 different mutations (seven so far unreported) (only one affected allele was identified in three subjects). A good correlation was found between genotype and clinical and biochemical phenotype. The occurrence of brain neurotransmitter deficiency and its early correction (by the therapy) are the main prognostic factors in PTPSd.

Homocysteine, reactive oxygen species and nitric oxide in type 2 diabetes mellitus.

INTRODUCTION: Type 2 diabetes mellitus shows a characteristic altered platelet function that can be due to several mechanisms such as oxidative stress. Hyperhomocysteinemia, considered as a risk factor for various arterial thrombosis, may have a role in generating oxidative damage, even if the pathogenic mechanisms are still not clear. In this report we aimed to determine the role of plasma homocysteine in inducing oxidative stress in type 2 diabetes mellitus. MATERIALS AND METHODS: The study was performed on a group of 34 males with type 2 diabetes and 36 healthy subjects matched for sex and age. Patients and healthy subjects were undergone to laboratory evaluation for plasma homocysteine levels and other metabolic parameters. In both groups of subjects platelet reactive oxygen species, nitric oxide and guanosine 3',5' cyclic monophosphate levels were measured. Moreover the reduced glutathione content in platelets of patients and of healthy subjects was assayed. RESULTS: Plasma homocysteine levels were significantly increased in patients compared with healthy subjects. The basal level of reactive oxygen species was significantly higher in patients than in controls. In addition platelets of patients stimulated with thrombin produced more reactive oxygen species than healthy subjects ones. The nitric oxide, guanosine 3',5' cyclic monophosphate and reduced glutathione content were decreased in platelets of patients. CONCLUSIONS: As homocysteine stimulates oxidative stress and inhibits nitric oxide formation, hyperhomocysteinemia measured in type 2 diabetic patients, promoting platelet hyperactivity, could have a role in the atherogenic effects described in type 2 diabetes.

The pathobiochemistry of uremia and hyperargininemia further demonstrates a metabolic relationship between urea and guanidinosuccinic acid.

To better understand the biosynthesis of guanidinosuccinic acid, we determined urea, arginine, and guanidinosuccinic acid levels in nondialyzed uremic and hyperargininemic patients. These substances were also determined during several years of therapy in one hyperarginiemic patient. Interrelationships of guanidinosuccinic acid levels with their corresponding urea and arginine levels were assessed by linear correlation studies. In uremic patients, a significant positive linear correlation (r = .821, p less than .001) was found between serum urea and guanidinosuccinic acid levels A significant positive linear correlation was also found between serum urea levels and urinary guanidinosuccinic acid levels (r = .828, P less than .001), but not between serum arginine levels and urinary guanidinosuccinic acid levels in hyperargininemic patients. In the intrahyperargininemic patient study, a similar significant positive correlation was found between serum urea levels and the corresponding urinary guanidinosuccinic acid levels (r = .866, P less than .001); the correlation between serum arginine levels and the corresponding urinary guanidinosuccinic acid levels was smaller. The presented analytical findings in uremic and hyperargininemic patients clearly demonstrate a metabolic relationship between urea and guanidinosuccinic acid.

Early-onset combined methylmalonic aciduria and homocystinuria: neuroradiologic findings.

BACKGROUND AND PURPOSE: Combined methylmalonic aciduria and homocystinuria (MMA-HC) is caused by impaired hepatic conversion of dietary cobalamin to methylcobalamin and adenosylcobalamin, resulting in decreased activity of methylmalonyl-CoA mutase and methionine synthase. Patients with the early-onset variety present within 12 months of age with severe neurologic, hematologic, and gastrointestinal abnormalities. We describe the neuroradiologic features of early-onset MMA-HC and discuss related pathophysiological mechanisms. METHODS: Twelve infants with hypotonia, failure to thrive, poor feeding, and hematologic abnormalities were diagnosed with MMA-HC on the basis of a typical plasmatic and urinary metabolic profile and enzyme activity in fibroblastic cultures. Complementation studies were performed in two cases, and yielded a CblC result. MR imaging was performed at presentation in four cases and later in the others. All patients showed prompt biochemical improvement with intramuscular hydroxocobalamin administration, and most had moderate neurologic improvement. RESULTS: Diffuse supratentorial white matter edema and dysmyelination was the typical MR picture at presentation, whereas white matter bulk loss characterized later stages of the disease. Nucleocapsular areas of gliosis were an additional finding in one case. One patient had tetraventricular hydrocephalus at presentation. CONCLUSION: White matter damage is probably caused by reduced methyl group availability and nonphysiological fatty acids toxicity, whereas focal gliosis results from homocysteine-induced toxicity to the endothelium. Hydrocephalus may result from diffuse intracranial extracerebral arterial stiffness, known as reduced arterial pulsation hydrocephalus. MR imaging features at presentation and at follow-up are nonspecific.

Determination of plasma and serum homocysteine by high-performance liquid chromatography with fluorescence detection.

Determination of homocysteine in plasma or serum is becoming an important diagnostic procedure. Accurate, rapid and low cost methods for measuring homocysteine are therefore required. We have improved an HPLC method and made it suitable for clinical application. The total homocysteine in plasma consists of free homocysteine (i.e., reduced plus oxidized homocysteine in the non-protein fraction of plasma) and protein-bound homocysteine. The method consists of the following steps: reduction of the sample with tri-n-butylphosphine, precipitation of proteins with trichloroacetic acid (10%) and derivatization with ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate. The derivatives are separated by reversed-phase high-performance liquid chromatography followed by fluorescence detection. The concentrations (mean +/- S.D.) of total homocysteine in plasma from 77 normal subjects, 44 male and 33 female adults, were 8.4 +/- 2.15 and 7.1 +/- 1.18 mumol/l, respectively. Serum concentrations were 8.8 +/- 2.6 mumol/l in males and 7.6 +/- 1.5 mumol/l in females.

Computed tomography in maple syrup urine disease.

Maple Syrup Urine Disease (MSUD) is an inherited metabolic disorder characterized by a severe, usually lethal, neonatal course in the early stages with pseudotumor cerebri and pathologically documented increased cerebral water content. CT and MRI studies in MSUD are few and the data are overlapping. This study reports CT features before and after dietary treatment in three patients; two with classical MSUD and one with an intermediate variant of MSUD. At diagnosis, CT consistently showed evidence of abnormally high lucidity involving not only white matter, but also areas of grey matter, particularly the pallidum. Furthermore, these CT changes are present both in the acute phase of classical MSUD and in an intermediate variant of the disease. The observed abnormalities evolve favorably under dietary treatment, simultaneously with clinical and neurological improvement. It is concluded that the observed CT changes indicate a diagnosis of MSUD and are relevant findings in the neuroradiologic differential diagnosis in acutely ill newborns, in which a metabolic disease may be not immediately suspected.

Purines and pyrimidines determination in urine using high-performance liquid chromatography.

Single purine and pyrimidine bases are involved in two fundamental metabolic pathways that lead to formation of the building stones of DNA and RNA. Purine and pyrimidine nucleotides are also critically important metabolites in many cellular functions. The main breakdown of purines and pyrimidines produces uric acid and B-minoacids, respectively. Therefore, the study of purine and pyrimidine compounds in body fluid has high clinical relevance. We report, in this work, our experience in purines and pyrimidines determination in urine from children presenting with a clinical picture suggesting an inborn these pathways.

[Plasma amino acids in dialyzed children: comparison of hemodialysis and continuous ambulatory peritoneal dialysis]. / Studio degli aminoacidi plasmatici nel bambino dializzato: confronto tra emodialisi e dialisi peritoneale ambulatoriale continua.

Plasma protein and amino acid concentrations have been reported to be abnormal in patients with chronic renal failure, whether on conservative or regular dialysis treatment. These abnormalities may be related to impaired protein and amino acid metabolism associated with uremia, to dietary deficiencies of calories and proteins or to amino acid and protein losses due to peritoneal dialysis or hemodialysis. Plasma free amino acid concentrations were evaluated in 17 children undergoing hemodialysis (HD) and 13 children treated by continuous ambulatory peritoneal dialysis (CAPD). Plasma levels of free amino acids showed a reduction of EAA and of the ratio EAA/NEAA. There were some abnormalities in plasma amino acid concentrations; these included decreased levels of valine, threonine, lysine, serine, tyrosine, arginine, alpha-ABA. Aspartate, glycine, citrulline, and, only in HD, cystine and methionine were increased. Plasma protein and amino acid concentrations in CAPD patients are similar to those found in HD patients; thus they result poorly affected by different dialysis techniques and the uremic state itself seems to play a more decisive role.

Metabolic and genetic risk factors for migraine in children.

Migraine can induce ischaemic stroke, and is considered an independent risk factor for stroke in the young. To date, the nature of the link between migraine and stroke is essentially unknown. Forty-five children were studied. Homocysteine levels (fasting and post methionine load), vitamin B12 and plasma folate levels, factor V Leiden, factor II G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C mutations were examined. Compared with controls, patients with migraine had higher levels of post-methionine load homocysteine values (19.5 +/- 4.9 vs. 16.9 +/- 1.9; P = 0.025) and significantly lower folate levels (5.8 +/- 2.6 vs. 7.5 +/- 2.1; P = 0.002). We found a trend toward an increased risk of migraine in subjects carrying a homozygous mutant genotype for MTHFR C677T and MTHFR A1298C polymorphisms. Genetic prothrombotic conditions do not seem to be related to migraine in the young, whereas the biochemical differences between migrainous patients and controls are an appealing topic for further investigation.

Pregnancy and tyrosinaemia type II.

A female patient with tyrosinaemia type II is reported having undergone two untreated pregnancies. During pregnancies, plasma tyrosine was raised. The outcomes of both offspring show that maternal tyrosinaemia may have an adverse effect on the developing fetus.

Tyrosinemia type III: diagnosis and ten-year follow-up.

Tyrosinemia type III, caused by deficiency of 4-hydroxyphenylpyruvate dioxygenase, is a rare disorder of tyrosine catabolism. Primary 4-hydroxyphenylpyruvate dioxygenase deficiency has been described in only three patients. The biochemical phenotype shows hypertyrosinemia and elevated urinary excretion of 4-hydroxyphenyl derivatives. We report the clinical and biochemical findings and the results of long-term follow-up in a new patient with this disorder presenting with severe mental retardation and neurological abnormalities. The clinical phenotype is compared with those reported in the three previously described patients.

Isolated sulphite oxidase deficiency: clinical and biochemical features in an Italian patient.

A patient with isolated sulphite oxidase deficiency presented with seizures at 12 h of life and followed a severe course, dying at 10 months of age. There was mild facial dysmorphism and the brain showed multiple cystic fibrosis.

Phenylketonuria: diet for life or not?

In order to evaluate the argument whether or not a restricted phenylalanine diet should be maintained for life in patients with phenylketonuria (PKU), 16 patients with early treated PKU but off diet since their 11th birthday were investigated. The evaluation included a detailed neurological examination, IQ, neurophysiological testing and MRI of the brain. Even if IQ and electrophysiological studies were normal or unchanged if compared to results before diet discontinuation, all patients revealed abnormal neurological signs. We conclude that the diet should be continued during adult life, but somewhat higher phenylalanine levels (<10mg/dl;<600 micromol/l) than at younger ages should be allowed.

[Evaluation of a new amino acid mixture for the treatment of phenylketonuria]. / Valutazione di una nuova miscela di aminoacidi per il trattamento della fenilchetonuria.

BACKGROUND: To assess the acceptability and nutritional adequacy of a new phenylalanine-free amino acid mixture (Phenylade-Dietetic Metabolic Food). METHODS: Twenty PKU patients (aged 2.6-10 years) diagnosed and followed by our Department. The children were given this product for a minimum of 4 and a maximum of 12 months. The clinical control has been carried out before treatment and then every 3 months. The biochemical parameters included: quantitative plasma amino acids, hematologic measurements of nutritional adequacy folic acid and vitamin B12. RESULTS: All patients (except one) found this new product to be an acceptable alternatives as to taste and convenience to the previous low phenylalanine protein substitutes. CONCLUSIONS: Normal growth was maintained.