Olav Borud

Fatal lactic acidosis in a newborn attributable to a congenital defect of pyruvate dehydrogenase.

Extract: An infant suffering from metabolic acidosis attributable to hyperlactatemia (6.1 mmol/liter) accompanied by hyperalaninemia (1 mmol/liter) and hyperserinemia (0.6 mmol/liter) is described. The urinary excretion of lactate and pyruvate was greatly elevated; the lactate to pyruvate ratio was normal. The urine showed low levels of citrate, isocitrate, and cis-aconitate, and low or normal levels of α-oxoglutarale, succinate, malate, and methylmalonate. Aspartate was slightly elevated in serum and urine, indicating a corresponding increase of its α-ketoacid oxaloacetate. These patterns of organic acids and amino acids suggested an in vivo defect in the oxidation of pyruvate. Fibroblasts cultured from skin biopsy from the patient metabolized radioactive pyruvate (final concentration 0.04–2 mmol/liter) to CO2 at rates from 5 to 17% of that of fibroblasts from normal control subjects. Enzyme studies with fibroblast sonicates revealed a severe deficiency of the pyruvate dehydrogenase complex (about 8% of normal), and this error was localized to the first unit of the complex, i.e., the pyruvate dehydrogenase (about 4% of normal). Fibroblasts from both parents metabolized pyruvate to CO2 at a slightly reduced rate, suggesting parental heterozygosity.Speculation: An exact classification, which may have both prognostic and therapeutic implications, of patients suffering from the heterogenous group of diseases, congenital lactic acidosis, will be possible only when the various underlying defects have been demonstrated. Since we are probably dealing with errors localized close to the center of the energy metabolism, sophisticated in vivo and in vitro studies will be required to reach this goal. However, we expect each defect to give rise to secondary derangements in the patterns of organic acids and amino acids in serum and urine, which are more or less typical for each defect. Once these patterns are known, a precise biochemical diagnosis may be reached by comparatively simple examinations.

Regulation of γ‐glutamyltransferase in cisplatin‐resistant and ‐sensitive colon carcinoma cells after acute cisplatin and oxidative stress exposures

Glutathione plays an important role in drug resistance of tumor cells and in their ability to resist oxidative stress. Improved salvage of glutathione can be obtained through increased activity of γ‐glutamyltransferase (GGT), which is of importance in the maintenance of cellular glutathione homeostasis. We investigated the regulation of GGT in 2 cisplatin‐resistant and 1 cisplatin‐sensitive colon carcinoma cell lines. Enzyme activity was induced in all 3 cell lines after acute exposure to cisplatin. The elevation was significantly higher in sensitive cells (3.3‐fold) than in resistant (1.6‐ to 1.7‐fold) cells. Exposure of cells to oxidative stress generated by menadione also resulted in enzyme induction but only in cisplatin‐sensitive cells. Addition of anti‐oxidants had different effects on the 2 inductions: N‐acetylcysteine blocked the induction of both cisplatin and menadione, whereas catalase and glutathione‐ester blocked only the menadione induction. Glutathione depletion alone was not sufficient to induce GGT in these cells. The data show that GGT is regulated by multiple mechanisms during anti‐tumor drug treatment and oxidative stress and that reactive oxygen species were involved in the menadione, but not cisplatin, induction of the enzyme. Int. J. Cancer 88:464–468, 2000.

Gas chromatographic and mass spectrometric studies on urinary organic acids in a patient with congenital lactic acidosis due to pyruvate decarboxylase deficiency

Detailed studies, using gas chromatography and mass spectrometric methods, of the urinary organic acids excreted by a patient with proven pyruvate decarboxylase deficiency are reported. In addition to the greatly-increased levels of lactate and pyruvate, marked elevation in the levels of 2-oxoglutaric, malic, and isocitric acids were observed, with associated increases 2-hydroxyglutaric, fumaric, succinic, and glyceric acids, and reduced citric acid excretion. The levels of excretion during clinically static and acute periods are compared to those in a normal neonate and normal infants. The metabolites observed indicate a probable defect in the oxidation of pyruvate by pyruvate dehydrogenase and suggest the presence of secondary defects in the tricarboxylic acid cycle. Studies of this type may enable the relatively rapid identification of the probable underlying enzyme deficiency in cases of congenital lactic acidosis, prior to confirmatory enzyme studies.

Dopamine-β-hydroxylase activity in serum following acute myocardial infarction: An evaluation of this parameter for routine use as an index of sympathetic activity

Dopamine-beta-hydroxylase activity was measured in sera from 114 normal males and from 11 patients on the 1st, 2nd, 3rd, 5th and 10th day following acute myocardial infarction. A significant elevation of dopamine-beta-hydroxylase levels (P less than 0.001) was found during the first two days after infarction when compared with the 10th-day values. Only a few activities were above the reference range. Temporary elevations of glucose and glycerol levels were also found. Assay of serum dopamine-beta-hydroxylase may be a useful parameter of sympathetic activity in longitudinal studies in which each individual is used as his own reference.

Hereditary Deafness in the Cat

The free amino acid and sugar content of cat perilymph was studied from 11 normal and 17 deaf ears, and compared with simultaneous estimations from cerebrospinal fluid and serum. Each fluid has a dist

Normal 2-aminobutyrate oxidation and increased valine oxidation in fibroblasts deficient in pyruvate dehydrogenase

Human skin fibroblasts deficient in pyruvate dehydrogenase and five normal control strains were incubated with one of the following labelled substrates:dl-[1-14C]-2-amino-n-butyric acid,dl-[3-14C]-2-amino-n-butyric acid,dl-[1-14C]leucine,l-[1-14C]valine,l-[1-14C]alanine, and [1-14C]pyruvate. The rate of14CO2-production in the deficient cells was normal from 2-aminobutyrate and leucine, increased from valine, and decreased from alanine and pyruvate. These results indicated that in human skin fibroblasts the decarboxylation of 2-oxobutyrate is catalysed by an enzyme system different from the pyruvate dehydrogenase complex.

Metabolic studies on normal and pyruvate dehydrogenase deficient cultured human fibroblasts.

Secondary metabolic derangements may occur in cultured fibroblasts with a defined enzyme deficiency. The metabolism of cells deficient of pyruvate dehydrogenase (5% of normal) has been studied using radioactive labelled substrates. Compared to normal control cells the activity of glycolysis was 149% (P less than 0.001), pentose phosphate shunt 144% (P less than 0.01), citric acid cycle 80% (P less than 0.002), and oxidation of acetate was 30% (P less than 0.01). The oxidation of palmitate and octanoate were not significantly different from that of control cells. Metabolic studies on fibroblasts may serve as a useful screening procedure for the detection of enzyme defects, but the results should be cautiously interpreted with respect to the localization of the primary defect.

Aspartylglycosaminuria in Northern Norway in eight patients: Clinical heterogeneity and variations with the diet

Urinary excretion of aspartylglycosamines was investigated in eight patients by semiquantitative thin-layer chromatography, and bound glycosamines by a quantitative photometric method (Elson-Morgan reaction). Each patient showed a fairly constant level, relative to the creatinine, of aspartylglycosamines in urine. The least retarded patient, aged 31, excreted about 350 mg/g creatinine, one-third of that found in two severely retarded young patients, aged 4 and 7 years (1400 and 940 mg/g creatinine, respectively). Three days on a low-protein diet did not change the aspartylglycosamine excretion in the patient showing the highest excretion rate.

Urinary organic acids in a case of congenital lactic acidosis due to pyruvate decarboxylase deficiency

Congenital lactic acidosis in the neonate and infant has been associated with deficiencies in the activity ofpyrurate carboxylase, the pyruvate dehydrogenase complex (deficiencies in pyruvate decarboxylase, in pyruvate decarboxylase phosphate phosphatase, and proposed deficiencies of either dihydrolipoyl transacetylase or dihydrolipoyl dehydrogenase), fructose-l,6-diphosphatase, g lucose -6 -phospha ta se , p h o s p h o e n o l p y r u v a t e carboxykinase and cytochrome-c-oxidase. Lactic acidosis has also been observed in a patient with a mitochondrial myopathy and cytochrome b deficiency, and defects in the tricarboxylic acid cycle and respiratory chain have also been proposed as causes of congenital lactic acidosis. Increased concentrations of lactic and pyruvic acids in particular, and of alanine and 2-oxoglutarate, in body fluids have been reported in various cases, but there have been no detailed reports of other organic acids in any of these disorders. This paper reports detailed studies, using quantitative extraction and derivatization coupled with gasliquid chromatography and mass spectrometry, on the organic acids in urine from a patient with congenital lactic acidosis due to pyruvate decarboxylase deficiency.

Secondary metabolic changes in fibroblasts from six patients with hereditary lactic acidosis.

Studies on fibroblasts from patients with lactic acidosis of different causes showed secondary metabolic changes in pathways of glucose metabolism. These secondary changes may be important clues to the diagnosis of the many different types of hereditary lactic acidosis.