Identification of two novel mutations C79X and R235Q in the dihydropyrimidine dehydrogenase gene in a patient presenting with hematuria.

A patient with hematuria was shown to have thymine-uraciluria. The dihydropyrimidine dehydrogenase (DPD) activity in peripheral blood mononuclear cells was 0.16 nmol/mg/h; controls: 9.

Contribution of various metabolites to the "unmeasured" anions in critically ill patients with metabolic acidosis.

Objective: The physicochemical approach, described by Stewart to investigate the acid-base balance, includes the strong ion gap (SIG), a quantitative measure of "unmeasured" anions, which strongly correlates to the corrected anion gap. The chemical nature of these anions is for the most part unknown. We hypothesized that amino acids, uric acid, and organic acids could contribute to the SIG.

Extended thiopurine metabolite assessment during 6-thioguanine therapy for immunomodulation in Crohn's disease.

The proposed metabolic advantage of 6-thioguanine (6-TG) is the direct conversion into the pharmacologically active 6-thioguaninenucleotides (6-TGN). The authors assessed metabolic characteristics of 6-TG treatment in patients with Crohn's disease (N = 7) on therapy with 20 mg 6-TG. 6-thioguanine-monophosphate (6-TGMP), 6-thioguanine-diphosphate (6-TGDP), and 6-thioguanine-triphosphate (6-TGTP) were measured by high-performance liquid chromatography analysis in erythrocytes.

Normal serum alanine concentration differentiates transient neonatal lactic acidemia from an inborn error of energy metabolism.

Background: Elevated blood lactate levels are common in the critically ill neonate; however, sometimes they are difficult to interpret. Persistent or recurrent lactic acidemia might point to an inborn error of metabolism, like disturbances of the oxidative phosphorylation. Chronic lactic acidemia results in increased serum alanine levels.

Cortical excitatory amino acid release and cell function during hypotension in near-term born lambs.

Background: Energy failure due to insufficient cerebral O2-supply leads to excess accumulation of calcium ions in presynaptic neurons, followed by excess release of excitatory amino acids, which are potent neurotoxins, into the synaptic cleft.

Aim: To investigate whether electrocortical brain activity (ECBA) can provide an adequate measure for excitatory amino acid release due to hemorrhagic hypotension.

Methods: Ten near-term lambs were delivered at 127 days of gestation (term: 147 days).

Measurement of the energy-generating capacity of human muscle mitochondria: diagnostic procedure and application to human pathology.

Background: Diagnosis of mitochondrial disorders usually requires a muscle biopsy to examine mitochondrial function. We describe our diagnostic procedure and results for 29 patients with mitochondrial disorders.

Methods: Muscle biopsies were from 43 healthy individuals and 29 patients with defects in one of the oxidative phosphorylation (OXPHOS) complexes, the pyruvate dehydrogenase complex (PDHc), or the adenine nucleotide translocator (ANT).

Stroke due to mitochondrial disorders in Saudi children.

Objective: To report on the clinical and biochemical features of patients who presented with stroke due to mitochondrial disorders amongst a prospective and retrospective cohort of Saudi children.

Methods: Children, who presented with stroke, were evaluated at the Division of Pediatric Neurology, or admitted to King Khalid University Hospital, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia, during the periods July 1992 to February 2001 (retrospective study) and February 2001 to March 2003 (prospective study). Open muscle biopsies were obtained from patients suspected to have mitochondrial disorders, and examined using conventional histological and histochemical techniques.

Supplemental oxygen prevents exercise-induced oxidative stress in muscle-wasted patients with chronic obstructive pulmonary disease.

Rationale: Although oxygen therapy is of clear benefit in patients with severe chronic obstructive pulmonary disease (COPD), recent studies have shown that short-term supplementary oxygen may increase oxidative stress and inflammation within the airways.

Objective: We investigated whether systemic inflammation and oxidative stress at rest and during exercise in patients with COPD are influenced by supplemental oxygen.

Methods: Nine normoxemic, muscle-wasted patients with moderate to very severe COPD were studied.

Excitatory amino acid release and electrocortical brain activity after hypoxemia in near-term lambs.

Background: Energy failure due to insufficient cerebral O(2)-supply leads to excess accumulation of calcium ions in presynaptic neurons, followed by excess release of excitatory amino acids (EAAs), which are potent neurotoxins, into the synaptic cleft.

Aim: The aim of the present study was to determine whether extracellular EAAs release after prolonged hypoxemia affects electrocortical brain activity (ECBA), as a measure of brain cell function, in near-term born lambs.

Methods: Ten near-term lambs (term: 147 days) were delivered at 131 days of gestation.

Cerebral cortical tissue damage after hemorrhagic hypotension in near-term born lambs.

Hypotension reduces cerebral O(2) supply, which may result in brain cell damage and loss of brain cell function in the near-term neonate. The aim is to elucidate 1) to what extent the functional disturbance of the cerebral cortex, as measured with electrocortical brain activity (ECBA), is related to cerebral cortical tissue damage, as estimated by MAP2; and 2) whether there is a relationship between the glutamate, nitric oxide (NO), cGMP pathway and the development of cerebral cortical tissue damage after hemorrhagic hypotension. Seven lambs were delivered at 131 d of gestation.

Moderate citrullinaemia without hyperammonaemia in a child with mutated and deficient argininosuccinate synthetase.

In a patient with microcephaly, feeding problems and restlessness, moderately increased serum and urine citrulline concentrations were observed. Protein and allopurinol loading did not result in additional indications for a urea cycle defect. The diagnosis of citrullinaemia was made at both the enzyme and DNA level, resulting from a novel mutation in the argininosuccinate synthetase gene.

Adenine nucleotide translocator 1 deficiency associated with Sengers syndrome.

Sengers syndrome is characterized by congenital cataracts, hypertrophic cardiomyopathy, mitochondrial myopathy, and lactic acidosis, but no abnormalities have been found with routine mitochondrial biochemical diagnostics (the determination of pyruvate oxidation rates and enzyme measurements). In immunoblot analysis, the protein content of the mitochondrial adenine nucleotide translocator 1 (ANT1) was found to be strongly reduced in the muscle tissues of two unrelated patients with Sengers syndrome. In addition, low residual adenine nucleotide translocator activity was detected upon the reconstitution of detergent-solubilized mitochondrial extracts from the patients' skeletal or heart muscle into liposomes.

Isolated sulfite oxidase deficiency: mutation analysis and DNA-based prenatal diagnosis.

Isolated sulfite oxidase deficiency is an autosomal recessive, neurological disorder resulting from a defect in SUOX, the gene encoding the enzyme that catalyzes the terminal reaction in the sulfur amino acid degradation pathway. In its classical, severe form, sulfite oxidase deficiency leads to intractable seizures, severe and progressive brain pathology and death at an early age. We report here on clinical features and mutational analysis of the genetic defect in a newborn with sulfite oxidase deficiency.

Immotile sperm and infertility in mice lacking mitochondrial voltage-dependent anion channel type 3.

Voltage-dependent anion channels (VDACs), also known as mitochondrial porins, are small channel proteins involved in the translocation of metabolites across the mitochondrial outer membrane. A single channel-forming protein is found in yeast, whereas higher eukaryotes express multiple VDACs, with humans and mice each harboring three distinct channels (VDAC1-3) encoded by separate genes. To begin to assess the functions of each of the three isoforms, the VDAC3 gene was inactivated by targeted disruption in embryonic stem cells.

End-stage liver disease as the only consequence of a mitochondrial respiratory chain deficiency: no contra-indication for liver transplantation.

Unlabelled: The prerequisite for liver transplantation as a therapeutic option for inherited metabolic diseases should be that the enzyme defect, being responsible for the major clinical (hepatic and/or extra-hepatic) abnormalities, is localised in the liver. Furthermore, no adequate dietary or pharmacological treatment should be available or such treatment should have an unacceptable influence on the quality of life. We report an infant, who developed end-stage liver disease with persistent lactic acidaemia in his first months of life.

Cerebral palsy and pyruvate dehydrogenase deficiency: identification of two new mutations in the E1alpha gene.

Unlabelled: Pyruvate dehydrogenase (PDH) complex deficiency, a common cause of congenital lactic acidosis, is mostly due to mutations in the X-linked gene coding for the E1alpha subunit of the complex. We have studied two unrelated girls presenting a static encephalopathy with spastic quadriplegia, microcephaly and seizures and in one girl, hypocalcaemia, a new finding in PDH complex deficiency. PDH deficiency was diagnosed in adolescence and both girls had low PDH complex activity in muscle but normal amounts of all subunits on Western blotting, and a normal lactate/pyruvate ratio in blood and CSF.

Pontocerebellar hypoplasia associated with respiratory-chain defects.

Pontocerebellar hypoplasias are congenital disorders of brain morphogenesis which include such diverse etiologies as carbohydrate-deficient glycoprotein syndrome type 1, cerebromuscular dystrophies (Walker-Warburg syndrome, Fukuyama syndrome, muscle-eye-brain disease) and at least two types of autosomal recessive neurodegenerations known as pontocerebellar hypoplasia type I and II. Pontocerebellar hypoplasia type 1 is a lethal phenotype and clinical features include congenital contractures, respiratory insufficiency, central and peripheral motor dysfunction and spinal anterior horn degeneration. Type 2 is characterized by progressive microcephaly, extrapyramidal dyskinesia and normal spinal cord findings.

Mapping of the human Voltage-Dependent Anion Channel isoforms 1 and 2 reconsidered.

Eukaryotic porins or VDACs (Voltage-Dependent Anion-selective Channels) are integral membrane proteins forming large hydrophilic pores. Three functioning genes for VDAC isoforms have been detected in mouse and the corresponding cDNAs are known also in humans. Tissue-specific VDAC isoform 1 (HVDAC1) deficiency in human skeletal muscle is responsible of a rare mitochondrial encephalomyopathy, fatal in childhood.

Spinal muscular atrophy-like picture, cardiomyopathy, and cytochrome c oxidase deficiency.

The authors report a child with a spinal muscular atrophy (SMA)-like picture, cardiomyopathy, and cytochrome c oxidase (COX) deficiency. Electromyography and muscle biopsy showed findings typical of SMA. However, COX staining of the muscle was negative.

A 4-base pair deletion in the mitochondrial cytochrome b gene associated with parkinsonism/MELAS overlap syndrome.

Five patients with diminished activity of complex III of the mitochondrial respiratory chain have been screened for mutations in the mitochondrial cytochrome b (cyt b) gene. In 1 patient, a young boy with an akinetic rigid syndrome and a mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), a novel 4-base pair deletion was identified. This mutation in this highly conserved gene is considered to be pathogenic since it is a heteroplasmic frame shift mutation predicted to lead to a truncated protein.

Molecular characterization and mutational analysis of the human B17 subunit of the mitochondrial respiratory chain complex I.

Bovine NADH:ubiquinone oxidoreductase (complex 1) of the mitochondrial respiratory chain consists of about 36 nuclear-encoded subunits. We review the current knowledge of the 15 human complex I subunits cloned so far, and report the 598-bp cDNA sequence, the chromosomal localization and the tissue expression of an additional subunit, the B17 subunit. The cDNA open reading frame of B17 comprises 387 bp and encodes a protein of 128 amino acids (calculated Mr 15.

Cytoarchitectural and metabolic adaptations in muscles with mitochondrial and cytosolic creatine kinase deficiencies.

We have blocked creatine kinase (CK) mediated phosphocreatine (PCr) <==> ATP transphosphorylation in mitochondria and cytosol of skeletal muscle by knocking out the genes for the mitochondrial (ScCKmit) and the cytosolic (M-CK) CK isoforms in mice. Animals which carry single or double mutations, if kept and tested under standard laboratory conditions, have surprisingly mild changes in muscle physiology. Strenuous ex vivo conditions were necessary to reveal that MM-CK absence in single and double mutants leads to a partial loss of tetanic force output.