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PubMed1981

Analysis of the oxocarboxylic acid fraction in serum and urine as O-methyloximes by thermionic specific detection.

After O-methyloximation of the carbonyl functions, the organic acids in serum and urine are extracted by anion-exchange chromatography, transformed into the methyl esters and pre-fractionated by thin-layer chromatography. In one of the four fractions and on the basis of the nitrogen in the O-methyloxime esters, the profiles of the oxocarboxylic acids are analyzed by gas chromatography with thermionic specific detection. The method has good specificity for the oxocarboxylic acids and is suitable for comparative studies. During diabetic or fasting ketoacidosis the serum concentrations of 3-oxobutyric acid and of the amino acid metabolites 2-oxobutyric, 2-oxoisovaleric and especially 2-oxo-3-methylvaleric and 2-oxoisocaproic acid are increased. In urine mainly 3-oxobutyric acid and only small amounts of the 2-oxocarboxylic acids are excreted.

Chromatography, Gas↗
PubMed2003

Influence of reproductive status on in vitro oocyte maturation in dogs.

In the bitch, oocytes need 48-72 h to complete post-ovulatory maturation to the metaphase II stage in the isthmus of the oviduct, an interval similar to that found in in vitro studies. The effect of estrous cycle stage on in vitro meiotic competence of dog oocytes has been described in several studies. However, there are no reports evaluating the possible effects of pyometra or pregnancy on subsequent potential of oocytes recovered from such females to undergo in vitro maturation. In this study, immature cumulus-oocyte complexes (COCs) were recovered from fresh excised domestic dog ovaries in various reproductive states. The donor females were classified into groups based on stage of the estrous cycle: follicular (proestrus or estrus), luteal (diestrus) or anestrus or at the clinical conditions of pregnancy and pyometra. Grades 1 and 2 oocytes were cultured in vitro at 37 degrees C in TCM-199, supplemented with 25 mM Hepes/l (v/v), and with 10% heat inactived estrous cow serum (ECS), 50 microg/ml gentamicin, 2.2 mg/ml sodium carbonate, 22 microg/ml pyruvic acid, 1.0 microg/ml estradiol, 0.5 microg/ml FSH and 0.03 IU/ml hCG. The nuclear maturation rate was evaluated at 72 h of incubation under Hoechst 33342 (10 microg/ml) staining for fluorescence microscopy. There was no statistical difference in nuclear progression to the MII stage among the various reproductive states (follicular phase, 5.4%; diestrus, 4.2%; anestrus, 4.4%; pyometra, 8.1% and pregnancy, 4.7%). Resumption of meiosis was 24.6% at the follicular phase, 19.6% for diestrus, 16.4% for anestrus, 37.1% for pyometra and 29.2% for pregnancy. Positive and higher numbers of residue above the expected value were observed for the pyometra and pregnancy conditions at the metaphase/anaphase I (MI/AI) stages.Our results indicate that in vitro nuclear maturation of dogs oocytes is not influenced by the in vivo reproductive status of the female. The quality of the oocyte is a more reliable indicator of its potential for meiotic maturation in vitro than the hormonal environment of the donor female at the time of oocyte retrieval.

Anaphase↗
PubMed1999

Neonatal presentations of mitochondrial metabolic disorders.

Because of the high energy requirements of the growing neonate, disorders of mitochondrial metabolism caused by defects in fatty acid oxidation, pyruvate metabolism, and the respiratory chain may often present in the neonatal period. Common neonatal presentations are hypotonia, lethargy, feeding and respiratory difficulties, failure to thrive, psychomotor delay, seizures, and vomiting. Laboratory clues include alterations in the levels of lactate, pyruvate (and the lactate/pyruvate ratio), glucose, and ketone bodies. Diagnosis usually depends on specific enzyme assays or on molecular genetic analysis. Without treatment, most infants die in the first few days or months of life. In the last decade, there have been significant advances in the understanding of the molecular basis of these disorders. This review discusses the major subgroups of mitochondrial disorders, focusing on defects of pyruvate oxidation, the Krebs cycle, and the respiratory chain. Disorders caused by respiratory chain defects may involve nuclear DNA, mitochondrial DNA, or intergenomic signaling. Recognition and early diagnosis of these conditions are important in the genetic counseling of these families.

DNA, Mitochondrial↗
PubMedDate not supplied

[Malignant hyperthermia during alcohol withdrawal].

Heat shock is the consequence of malignant hyperthermia triggered by general anaesthesia, the use of neuroleptic drugs, or strenuous muscular exercise. Chronic alcoholism could be a contributing factor by facilitating the triggering of malignant hyperthermia. We describe two cases of malignant hyperthermia which occurred during the summer in undernourished chronic alcoholics showing withdrawal syndrome during their stay in hospital. General anaesthesia and neuroleptics were excluded as the origin of their malignant hyperthermia, and we looked for new mechanisms to explain the heat shock, other than shivering associated with the withdrawal syndrome or the high temperature of the season. These two patients were considered deficient in thiamine on admission, their plasma pyruvic acid level being sharply increased (185 mumol/l and 304 mumol/l respectively; normal range: 45.6-91.2 mumol/l). This deficiency can lead to disregulation of thermal centres. Other metabolic disorders, frequently observed in alcoholics, could facilitate heat release during withdrawal syndrome shivering. The risk of heat shock during abrupt alcohol withdrawal should not be underestimated.

Adult↗
PubMed1978

Effect of Di-(2-ethylhexyl) phthalate (DEHP) on chemical constituents and enzymatic activity of rat liver.

Effect of Di(2-ethylhexyl) phthalate (DEHP), was investigated on chemical constituents and activity of certain enzymes of rat liver. A significant increase in liver weight; total and relative to body weight; decrease in total, free and esterified cholesterol; and no change in dry weight, moisture; RNA, DNA, total lipids, phospholipids, pyruvic acid and lactic acid contents was observed in liver of DEHP-treated rats as compared to controls. Activity of 3 mitochondrial enzymes, malic dehydrogenase, cytochrome-c-oxidase and diaphorase were significantly decreased while that of NADH-cytochrome c reductase, RNAase and DNAase remained unaltered upon treatment. The results suggest that DEHP exerts its hepatotoxic effects by interfering with bioenergetics of the cell.

Animals↗
PubMed1997

Clinical and radiologic improvements in mitochondrial encephalomyelopathy following sodium dichloroacetate therapy.

We administered sodium dichloroacetate (DCA), which reduces the circulating lactate and pyruvate concentrations by stimulating the activity of the pyruvate dehydrogenase complex (PDHC), to three children with mitochondrial encephalomyelopathy. Significant clinical, biochemical and radiologic improvements were obtained following DCA therapy (approximately 30 mg/kg per day, divided into three doses). All three patients had non-pyruvate dehydrogenase complex (PDHC) deficiencies: two exhibited Leigh syndrome (complex I deficiency and unknown etiology), and one abnormal myelination (multienzyme deficiency), demonstrated on magnetic resonance imaging (MRI). The lactic and pyruvic acid concentrations in serum and cerebrospinal fluid (CSF) were decreased significantly by the oral DCA treatment. The lactic acid peak on MR spectroscopy also markedly decreased in parallel with the CSF level. In addition, the brain lesions observed on MRI were improved in all patients. No exacerbation was observed in any of the patients, who have been followed-up more than 21 months following the DCA therapy. These results suggest that DCA therapy should be considered in all patients with a mitochondria-related enzyme deficiency.

Brain↗
PubMed1998

Congenital ocular motor apraxia associated with myopathy, external hydrocephalus and NADH dehydrogenase deficiency.

Congenital ocular motor apraxia (COMA), first described by Cogan [Trans Am Acad Ophthalmol Otolaryngol 1952;56:853-862], is a rare disorder characterized by impairment of voluntary and optically induced horizontal eye movements and compensatory head thrust. The causes and pathogenesis of COMA are poorly understood. It frequently occurs in association with other neurologic abnormalities including non-progressive congenital disorders of the central nervous system (CNS), various systemic diseases and chromosomal alterations. Here, we report the case of a 6-month-old girl with psychomotor retardation, myopathy and clinical features of COMA, associated with external hydrocephalus and mitochondrial dysfunction (partial deficiency of the respiratory-chain enzyme NADH dehydrogenase). In view of this finding, we recommend that tests to characterize patients with COMA should include determination of blood levels of lactic and pyruvic acid.

Apraxias↗
PubMed1999

Common deletion of mitochondrial DNA in a 5-year-old girl with failure to thrive, ptosis, ophthalmoplegia and ragged-red fibers.

A girl aged 4 years and 10 months presented with failure to thrive, ptosis, ragged-red fibers and the common 4.9 kb mitochondrial DNA deletion. She had elevated serum lactic and pyruvic acids. The onset was at around 18 months. There were no signs of retinitis, and abnormal renal, liver or pancreatic functions. She later developed mild ophthalmoplegia at 6 years of age. Additional features of chronic progressive external ophthalmoplegia (CPEO) or Kearns-Sayre syndrome (KSS) are the conditions that should be watched and investigated in the long-term follow-up of this girl.

Adenosine Triphosphatases↗
PubMed1998

mtDNA nt3243 mutation, external ophthalmoplegia, and hypogonadism in an adolescent girl.

A 14-year-old girl presented with a 3-month history of easy fatigue and exercise intolerance, especially when climbing stairs. She had a mild ptosis and mild limitation of upward gaze. Her puberty was delayed, and she manifested hypogonadotrophic hypogonadism. Serum lactic and pyruvic acids were elevated. Cranial magnetic resonance imaging was normal. Muscle biopsy documented typical ragged-red fibers. A point mutation at nucleotide 3243 in the tRNALeu(UUR) (typical mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) mutation) was detected in mitochondrial DNA from both blood and muscle tissues, indicating that our patient was suffering from a mitochondrial myopathy. Hypogonadism may be a manifestation of the MELAS nucleotide 3243 mutation.

Adolescent↗
PubMed1998

Prolyl hydroxylase activity in tissue homogenates of annelids from deep sea hydrothermal vents.

Tissue homogenates of the deep sea annelids Alvinella caudata and Alvinella pompejana were found to contain enzyme activity resembling vertebrate prolyl 4-hydroxylase. The release of 3H2O from [3,4-(3)H]proline labeled, under-hydroxylated chicken protocollagen type I depended on the presence of the cofactors 2-oxoglutarate, ascorbate, Fe2+ and O2. The release of 3H2O could be inhibited by the prolyl 4-hydroxylase inhibitors zinc, 2,2'-dipyridyl, 3,4-dihydroxybenzoic acid and pyridine-2,4-dicarboxylate, as well as by the synthetic peptide (Pro-Pro-Gly)10. This synthetic peptide could also serve as substrate, because it enhanced the decarboxylation of 2-oxo[5-(14)C]glutarate. Alvinella prolyl hydroxylase appeared to be related to type II vertebrate enzyme because of its lack of affinity for poly (L-proline) and resistance to inactivation by an irreversible peptide inhibitor of chicken prolyl 4-hydroxylase. Maximal enzyme activity was observed in solutions with less than 10% oxygen saturation. By contrast, chicken enzyme was most active at saturating oxygen concentrations. Further data suggest that the Alvinella enzymes are able to accept the 2-oxo acids pyruvate, oxaloacetate and 2-oxoadipinate as substitutes of the cosubstarate 2-oxoglutarate. The data explain the high hydroxylation of Alvinella collagens despite the low oxygen concentrations around hydrothermal vents.

Animals↗
PubMed2003

The preparation of (S)-aspartate semi-aldehyde appropriate for use in biochemical studies.

We report two three-step syntheses of (S)-aspartate semi-aldehyde, an important synthetic and biosynthetic precursor, from diprotected aspartic acid. The first synthesis proceeds via a thioester, the second via a Weinreb amide. Each route yields pure (S)-aspartate semi-aldehyde in excellent yield. (S)-Aspartate semi-aldehyde prepared in this manner has proved appropriate as a substrate for detailed enzyme studies.

Aspartic Acid↗
PubMed1984

The Quebec Cooperative Study of Friedreich's Ataxia: 1974-1984--10 years of research.

In this paper the author reviews the progress accomplished in the understanding of Friedreich's disease since the start of the "Quebec Cooperative Study of Friedreich's Ataxia" in 1974. The last ten years have indeed seen important strides taken in the definition and nosography of the hereditary ataxias and the characterization of a number of new entities. Biochemically, the principal leads uncovered during the initial prospective survey, have been pursued to great detail. Unfortunately no clear-cut constant and severe enzyme block in the principal metabolic pathways has yet been identified, despite intensive studies. It is postulated that the defect may instead be a regulatory one and involve a decreased availability or utilization of one of the vitamin cofactors that are known experimentally, or clinically, to produce central nervous system damage with ataxia: Vitamin E, Biotin or Pantothenic Acid. Studies in that direction and in molecular genetics to localize the Friedreich's disease gene are being undertaken for the next phase of the Cooperative Study.

Amino Acids↗
PubMed1982

Quantitative metabolic profiling of alpha-keto acids in Friedreich's ataxia.

The plasma distribution of alpha-keto acids was measured in 26 subjects including 8 patients with Friedreich's ataxia, 8 with the recessive spastic ataxia of Charlevoix-Sageunay and 10 healthy volunteers. The groups were matched with regards to age, sex, weight and the study was conducted under standardized dietary intake. The result indicate significant differences in the alpha-keto acids distribution between the groups.

Adult↗
PubMed1987

Stereochemistry and mechanism of a new single-turnover, half-transamination reaction catalyzed by the tryptophan synthase alpha 2 beta 2 complex.

Tryptophan synthase is a versatile enzyme that catalyzes a wide variety of pyridoxal phosphate dependent reactions that are also catalyzed in model systems. These include beta-replacement, beta-elimination, racemization, and transamination reactions. We now show that the apo-alpha 2 beta 2 complex of tryptophan synthase will bind two unnatural substrates, pyridoxamine phosphate and indole-3-pyruvic acid, and will convert them by a single-turnover, half-transamination reaction to pyridoxal phosphate and L-tryptophan, the natural coenzyme and a natural product, respectively. This enzyme-catalyzed reaction is more rapid and more stereospecific than an analogous model reaction. The pro-S 4'-methylene proton of pyridoxamine phosphate is removed during the reaction, and the product is primarily L-tryptophan. We conclude that pyridoxal phosphate enzymes may be able to catalyze some unnatural reactions involving bound reactants and bound coenzyme since the coenzyme itself has the intrinsic ability to promote a variety of reactions.

Escherichia coli↗
PubMed1988

Cytochrome P-450 inactivation by 3-alkylsydnones. Mechanistic implications of N-alkyl and N-alkenyl heme adduct formation.

Incubation of 3-(2-phenylethyl)-4-methylsydnone (PMS) with liver microsomes from phenobarbital-pretreated rats or with reconstituted cytochrome P-450b results in loss of the enzyme chromophore. Chromophore loss is NADPH-dependent even though the sydnone decomposes by an oxygen- but not enzyme-dependent process to give pyruvic acid and, presumably, the (2-phenylethyl)diazonium cation. N-(2-Phenylethyl)protoporphyrin IX and N-(2-phenylethenyl)protoporphyrin IX have been isolated from the livers of rats treated with PMS. Both deuteriums are retained in the N-(2-phenylethyl) adduct derived from 3-(2-phenyl[1,1-2H]ethyl)-4-methylsydnone, but one deuterium is lost in the N-(2-phenylethenyl) adduct. The N-(2-phenylethyl) to N-(2-phenylethenyl) adduct ratio is increased by deuterium substitution. No spectroscopically detectable intermediates precede chromophore loss in incubations of reconstituted cytochrome P-450b with PMS. Electron paramagnetic resonance (EPR)-spin trapping studies show that carbon radicals are formed in incubations of the sydnones with liver microsomes but by a process that is independent of chromophore destruction. It is proposed that the 2-phenylethyl radical formed by electron transfer to the sydnone-derived (2-phenylethyl)diazonium cation adds to the prosthetic heme group to give the N-(2-phenylethyl) adduct. This alkylation reaction is similar to that observed with (2-phenylethyl)hydrazine. Autoxidation of the Fe-CH(CH2Ph)-N bridged species expected from insertion of 2-phenyldiazoethane into one of the heme Fe-N bonds is proposed to explain the unprecedented introduction of a double bond into the N-(2-phenylethenyl) adduct.

Animals↗