The mitochondrial-targeted reactive species scavenger JP4-039 prevents sulfite-induced alterations in antioxidant defenses, energy transfer, and cell death signaling in striatum of rats.

Sulfite oxidase (SO) deficiency is a disorder caused either by isolated deficiency of SO or by defects in the synthesis of its molybdenum cofactor. It is characterized biochemically by tissue sulfite accumulation. Patients present with seizures, progressive neurological damage, and basal ganglia abnormalities, the pathogenesis of which is not fully established. Treatment is supportive and largely ineffective. To address the pathophysiology of sulfite toxicity, we examined the effects of intrastriatal administration of sulfite in rats on antioxidant defenses, energy transfer, and mitogen-activated protein kinases (MAPK) and apoptosis pathways in rat striatum. Sulfite administration decreased glutathione (GSH) concentration and glutathione peroxidase, glucose-6-phosphate dehydrogenase, glutathione S-transferase, and glutathione reductase activities in striatal tissue. Creatine kinase (CK) activity, a crucial enzyme for cell energy transfer, was also decreased by sulfite. Superoxide dismutase-1 (SOD1) and catalase (CAT) proteins were increased, while heme oxygenase-1 (HO-1) was decreased. Additionally, sulfite altered phosphorylation of MAPK by decreasing of p38 and increasing of ERK. Sulfite further augmented the content of GSK-3ß, Bok, and cleaved caspase-3, indicating increased apoptosis. JP4-039 is a mitochondrial-targeted antioxidant that reaches higher intramitochondrial levels than other traditional antioxidants. Intraperitoneal injection of JP4-039 before sulfite administration preserved activity of antioxidant enzymes and CK. It also prevented or attenuated alterations in SOD1, CAT, and HO-1 protein content, as well as changes in p38, ERK, and apoptosis markers. In sum, oxidative stress and apoptosis induced by sulfite injection are prevented by JP4-039, identifying this molecule as a promising candidate for pharmacological treatment of SO-deficient patients.

Acute and chronic hypermethioninemia alter Na+ K+-ATPase activity in rat hippocampus: prevention by antioxidants.

In the current study we initially investigated the influence of antioxidants (vitamins E plus C) on the effect mediated by acute and chronic administration of methionine (Met) on Na(+),K(+)-ATPase activity in rat hippocampus. We also verified whether the alterations on the enzyme after administration of Met and/or antioxidants were associated with changes in relative expression of Na(+),K(+)-ATPase catalytic subunits (isoforms α1, α2 and α3). For acute treatment, young rats received a single subcutaneous injection of Met or saline (control) and were sacrificed 12 h later. In another set of experiments, rats were pretreated for 1 week with daily intraperitoneal administration of vitamins E (40 mg/kg) and C (100 mg/kg) or saline. After that, rats received a single injection of Met or saline and were killed 12 h later. For chronic treatment, Met was administered to rats from the 6th to the 28th day of life; controls and treated rats were sacrificed 12 h after the last injection. In parallel to chronic treatment, rats received a daily intraperitoneal injection of vitamins E and C from the 6th to the 28th day of life and were killed 12 h after the last injection. Results showed that administration of antioxidants partially prevented the inhibition of enzyme activity caused by acute and chronic hypermethioninemia. Besides, we demonstrated that transcription of catalytic subunits of Na(+),K(+)-ATPase was not altered by chronic and acute exposure to Met and/or vitamins E plus C. These data strongly suggest the oxidative damage as one possible mechanism involved in the reduction of Na(+),K(+)-ATPase activity caused by hypermethioninemia and if confirmed in human beings, we might propose the use of antioxidants as an adjuvant therapy in hypermethioninemic patients.

Newborn screening.

Screening newborns for inherited disorders provides an opportunity for pre-symptomatic identification and early intervention to prevent or mitigate morbidity and mortality associated with these conditions. Since the introduction of newborn screening in 1962 to screen for phenylketonuria, technological advances have enabled the screening panel to expand substantially so that it now includes more than 50 disorders. Newborn screening will continue to evolve,, and deployment of improved methodologies and incorporation of additional disorders are expected. This article provides an overview of the current state of newborn screening, and describes the disorders detectable, the methodologies employed, and the challenges involved in analyses of specimens obtained from newborns.

Glutaric acidemia type I: a neurosurgical perspective. Report of two cases.

Glutaric acidemia type I (GA-I) is a rare, autosomal recessive metabolic disorder that leads to severe dystonia, basal ganglia degeneration, and bilaterally enlarged anterior middle cranial fossae. The current management of this disease includes early diagnosis with newborn screening, prevention of catabolism, carnitine supplementation, and a strict dietary protein restriction. Neurosurgical evaluation and intervention may be necessary in patients with structural lesions associated with this disease. In this report, the authors present two pediatric patients with GA-I and discuss the neurosurgical aspects of this rare medical disorder.

Prenatal counseling in heterozygotes for ornithine transcarbamylase deficiency.

X-linked ornithine transcarbamylase deficiency (OTCD) often leads to fatal neonatal hyperammonemia in affected males (hemizygotes). In prenatal management of subsequent pregnancies, families carrying female fetuses are often reassured of the low risk of clinically overt disease. We suggest that such reassurance may be misleading. While OTCD heterozygotes may show no symptoms or only mild protein intolerance, the clinical course in a fraction of children can include manifestations similar to those in affected males. We present three cases of symptomatic and previously undiagnosed OTCD heterozygotes to illustrate the potential severity of this condition. Significant improvement in function and growth followed diagnosis and treatment; however, two of the three children remain significantly developmentally delayed. While a quantitative risk estimate cannot be derived from these data, the cases are indicative of an adverse outcome in manifesting heterozygotes. Accordingly, OTCD carrier families should be counseled regarding the possibility of significant hyperammonemia, neurologic deficit, and the need for pharmacologic and dietary intervention in their heterozygote daughters.

Selective screening for amino acid disorders.

The analysis of amino acids is the most frequently applied technique in the selective screening of inborn errors of metabolism. When urine is used as a starting material, simple techniques such as thin-layer chromatography or high-voltage electrophoresis is preferred as a first approach. The quantitative analysis requires instrumentation, usually an amino acid analyser. Both plasma and urine are needed for establishing renal transport defects. Apart from the accumulation of the 'usual' amino acids, the presence of unusual amino acids may be of diagnostic significance. Furthermore the finding of decreased plasma concentrations of specific amino acids may pinpoint several inherited defects. No amino acid screening procedure is complete without the availability of an organic acid and a purine/pyrimidine analytical system, both yielding important additional diagnostic information. Considerable clinical problems may occur in subjects with a decreased tolerance to protein amino acids without being homozygous for any inherited defect. Examples of these disorders that need further studies are homocysteinaemia associated with vascular disease and carriers of ornithine transcarbamylase deficiency.

Screening for defects of branched-chain amino acid metabolism.

Screening for defects of branched-chain amino acid metabolism is a sequential process involving clinical evaluation of the patient, plasma carnitine determination, urinary organic acid analysis, and enzyme studies in cultured or isolated peripheral cells. This report will summarize clinical and metabolite features and enzymological methods available for the diagnosis of the more common defects of branched-chain amino acid metabolism, including isovaleryl-CoA dehydrogenase deficiency, 3-methylcrotonyl-CoA carboxylase deficiency, 3-methylglutaconic aciduria due to 3-methylglutaconyl-CoA hydratase deficiency and other less well characterized defects, 3-hydroxy-3-methylglutaryl-CoA lyase deficiency, and 2-methylacetoacetyl-CoA thiolase deficiency. Newer enzymatic methodologies utilizing NaH14CO3 fixation coupled assays are described which allow for the estimation of six enzyme activities in the catabolic pathways of L-leucine and L-isoleucine catabolism. These coupled assays facilitate the rapid identification of five of the six enzyme abnormalities described above. Their ease of use should allow them to be implemented in any laboratory which screens for inborn errors of metabolism.

[Biochemical diagnosis and mass screening for hereditary amino acid disorders].

During the past 50 years, the development of both organic and analytical chemistry has greatly contributed to the discovery of new hereditary amino acid disorders. As a result, more than 80 new amino acid disorders have been discovered. More recently, the development of protein chemistry has made it easily to investigate the biochemical basis of these disorders. In this paper we present the status of biochemical diagnosis as well as mass-screening for amino acid disorders. The result of neonatal mass-screening for 4 amino acid disorders (PKU, MSUD, homocystinuria and histidinemia) from 1977 to 1990 revealed that the incidence of PKU is extremely rare in Japan when compared to European Countries, and the incidence of MSUD and homocystinuria are also less common in Japan. On the other hand, the incidence of histidinemia is higher in Japan than in Europe, however, a follow up study of more than 1,500 patients showed almost all cases developed normally without any dietary treatment.

[Selective screening for amino and organic acid inborn errors]. / Selektives Screening auf Amino- und Organoazidopathien.

Aminoacidopathies and organoacidopathies are the most common acute life-threatening inborn errors of metabolism in the neonatal period. In the Federal Republic of Germany approximately 1 out of 5000 newborns is currently diagnosed as having an aminoacidopathy and approximately 1 out of 9000 newborns an organoacidopathy. Especially in the case of organoacidopathies there is substantial evidence that this number represents an underestimation. Many cases of amino- and organoacidopathies are still likely to remain undiagnosed. The incidence figures would warrant neonatal population screening for these disorders; however, the complexity and expense of the current methods prohibit this approach. Instead specialized investigations are carried out in children who develop symptoms indicative of an inborn error of metabolism. This approach is called selective screening. Early diagnosis, therefore, rests on a high degree of suspicion. In this paper clinical and laboratory findings of amino- and organoacidopathies are summarized. They can be nonspecific and misinterpreted. In the neonate and infant the presentation is commonly that of an acute overwhelming disease, whereas in the older child unexplained mental and/or neurological problems are often the leading symptom. We present an algorithm for the quick and comprehensive diagnosis of acutely presenting inborn errors of metabolism using commonly available parameters. However, in many cases the definitive diagnosis is not reached by selective metabolic screening of a single urine specimen of a patient, but requires close cooperation between the referring physician and the metabolic specialist. Multiple analyses, sometimes of different physiological fluids, or even in vivo and in vitro loading tests may be necessary.(ABSTRACT TRUNCATED AT 250 WORDS)

Prospective treatment of urea cycle disorders.

We present a diagnostic and therapeutic protocol designed to prevent clinical expression of inborn errors of urea synthesis in the neonatal period, and discuss the long-term developmental outcome of survivors. The families of 32 infants, among 43 identified prenatally as being at risk for a urea cycle disorder, chose to have their infants treated according to a diagnostic and therapeutic protocol, beginning at birth. The therapy was effective in avoiding neonatal hyperammonemic coma and death in seven patients with carbamoyl phosphate synthetase deficiency, argininosuccinate synthetase deficiency, and argininosuccinate lyase deficiency. When treated prospectively, five of eight patients with ornithine transcarbamylase deficiency avoided severe hyperammonemia and survived the neonatal period. Two patients with carbamoyl phosphate synthetase deficiency and two with ornithine transcarbamylase deficiency have subsequently died; three additional patients with the latter disorder have received orthotopic liver transplants. Our experience suggests that these surviving patients have had a more favorable neurologic outcome than patients rescued from neonatal hyperammonemic coma. However, all of them require a burdensome medical regimen and may have handicaps that include impairment of development and recurrent episodes of hyperammonemia. Further, those with deficiency of carbamoyl phosphate synthetase or ornithine transcarbamylase have a high mortality rate.

Screening for inborn errors of amino acid metabolism.

Early diagnosis and treatment may prevent brain damage and mental retardation in young infants with inborn errors of amino acid metabolism. The abnormal blood and urinary amino acids and their metabolites are listed in two separate tables in association with each disorder to aid laboratories in making a diagnosis during screening. Because of recent developments and discoveries, more detailed descriptions and diagnostic approaches in phenylketonuria (PKU) variants and urea cycle deficiencies are also presented. The test procedures routinely used for screening inherited metabolic disorders are also described. These include five simple chemical tests to detect excessive metabolites and amino acids; a one dimensional thin layer chromatography (TLC) to screen urine for abnormal amino acid patterns; a two-dimensional TLC for semiquantitative identification of amino acids in both urine and blood; and a high performance liquid chromatographic (HPLC) method for quantitative identification of amino acids. In addition, both one- and two-dimensional chromatographies run on small thin layer cellulose plates, are introduced, modifications which save a great deal of time, labor, and reagents. A new automated HPLC system is introduced for the quantitation of both primary and secondary amino acids; the sensitivity and speed of this system is especially useful for screening large numbers of physiological fluids. It is recommended that both the urine and blood from the same patients be screened to ensure that a diagnosis is not overlooked.

Fertility in couples heterozygous for the tyrosinemia gene in Saguenay Lac-St-Jean.

A case-control study of 84 couples from Saguenay-Lac-St-Jean, jointly heterozygous for the tyrosinemia gene, was done to determine whether the birth of an homozygous child affected their fertility rates. The mean number of children born to tyrosinemia and control couples between 1940 and 1986 was not different (p greater than 0.05). The knowledge that tyrosinemia was an autosomal recessive disorder, with risk of recurrence in these families, did not appear to modify reproductive behaviour. Fertility fell significantly in both the tyrosinemia and control families in the period of observation. This change reflects the decline in fertility of French Canadians in general during this period.

Potassium ion ionization of desorbed species (K+IDS): a rapid method for the screening of urine for organic acidemias.

A new desorption/ionization mass spectrometric technique, K+ ionization of desorbed species (K+IDS), is evaluated as a rapid method for differentiating various organic acidemias, conditions in which excessive levels of organic acid metabolites are present in plasma or urine as a result of some inborn error of metabolism. This method requires no derivatization of the isolated organic acids, unlike that required for gas chromatographic and gas chromatographic/mass spectrometric analyses. 'Batch' mass spectrometric analysis is achieved by deposition of the complex organic acid mixture (from urine) onto a K+IDS probe. Rapid heating results in the emission of alkali ions (Na+ or K+) from a thermionic emitter and the intact desorption of analyte. Subsequent gas-phase addition produces a mass spectrum showing alkali ion adducts of the components, providing molecular weight and relative concentration information. This rapid desorption/ionization technique requires no matrix, and analysis times are exceedingly short relative to those required in gas chromatographic/mass spectrometric analyses. Results suggest that differential diagnosis of some of the more commonly occurring organic acidemias (e.g. isovaleric acidemia, maple syrup urine disease, etc.) may be made.