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Biomedical subjects

G Finocchiaro

Publications and source records attributed to G Finocchiaro.

At least 91 records · Page 5Linked to original sources

Molecular cloning and nucleotide sequence of cDNAs encoding the alpha-subunit of human electron transfer flavoprotein.

cDNAs encoding the precursor of the alpha-subunit of human electron transfer flavoprotein (p alpha-ETF) were cloned and sequenced. The cDNAs span 1,300 base pairs and include the entire coding region of 333 amino acids. The identity of the p alpha-ETF clones was confirmed by hybrid selected translation, by transcription/translation of a cDNA, and by mitochondrial processing of the protein produced by these translations. The identity of the cDNA clones was further confirmed by matching the amino acid sequence deduced from the nucleotide sequence of the cDNAs to amino acid sequences determined from seven tryptic peptides prepared from purified rat alpha-subunit of electron transfer flavoprotein (alpha-ETF). Ninety-eight of 105 amino acids from these rat alpha-ETF tryptic peptides matched with those deduced from the human cDNAs. The seven amino acid substitutions are presumably due to species difference. The calculated molecular weight of the human alpha-ETF precursor was 35,084. The amino-terminal amino acid of the mature protein could not be determined by amino-terminal sequencing, presumably due to blockage and, therefore, an accurate molecular weight of mature alpha-ETF could not be calculated. The molecular sizes of the precursor and mature alpha-ETF have been estimated to be 35 and 32 kDa, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Amino Acid Sequence↗

Genetic deficiency of short-chain acyl-coenzyme A dehydrogenase in cultured fibroblasts from a patient with muscle carnitine deficiency and severe skeletal muscle weakness.

Genetic deficiency of short-chain acyl-coenzyme A (CoA) dehydrogenase activity was demonstrated in cultured fibroblasts from a 2-yr-old female whose early postnatal life was complicated by poor feeding, emesis, and failure to thrive. She demonstrated progressive skeletal muscle weakness and developmental delay. Her plasma total carnitine level (35 nmol/ml) was low-normal, but was esterified to an abnormal degree (55% vs. control of less than 10%). Her skeletal muscle total carnitine level was low (7.6 nmol/mg protein vs. control of 14 +/- 2 nmol/mg protein) and was 75% esterified. Mild lipid deposition was noted in type I muscle fibers. Fibroblasts from this patient had 50% of control levels of acyl-CoA dehydrogenase activity towards butyryl-CoA as substrate at a concentration of 50 muM in a fluorometric assay based on the reduction of electron transfer flavoprotein. All of this residual activity was inhibited by an antibody against medium-chain acyl-CoA dehydrogenase. These data demonstrated that medium-chain acyl-CoA dehydrogenase accounted for 50% of the activity towards the short-chain substrate, butyryl-CoA, under these conditions, but that antibody against that enzyme could be used to unmask the specific and virtually complete deficiency of short-chain acyl-CoA dehydrogenase in this patient. Fibroblasts from her parents had intermediate levels of activity towards butyryl-CoA, consistent with the autosomal recessive inheritance of this metabolic defect.

Acyl-CoA Dehydrogenase↗

Glucose metabolism alterations in Friedreich's ataxia.

We have characterized the abnormalities of glucose metabolism associated with Friedreich's ataxia (FA) by studying plasma glucose, insulin, growth hormone (GH), and glucagon before and after an oral glucose tolerance test (OGTT), an IV glucose load, and an IV arginine load, in 21 patients and in controls. Twelve patients were normotolerant (NT) to glucose, five glucose-intolerant (IT), and four diabetic (DM). Insulin secretion of IT patients was increased and delayed during OGTT. Interestingly, the insulin release during arginine load was significantly decreased in NT and IT as well as in DM patients. The GH response to OGTT was altered in IT patients. Plasma glucagon after an arginine load was significantly higher in patients than in controls. The results indicate that FA is associated with insulin resistance, beta-cell deficiency, and type I diabetes. These alterations might be genetically linked or metabolically related to the primary defect in FA. Their interplay or independent effects are responsible for abnormalities of glucose metabolism in FA.

Adolescent↗

Molecular cloning and nucleotide sequence of cDNA encoding the entire precursor of rat liver medium chain acyl coenzyme A dehydrogenase.

cDNA encoding the precursor of rat liver medium chain acyl-CoA dehydrogenase (EC 1.3.99.3) was cloned and sequenced. The longest cDNA insert isolated was 1866 bases in length. This cDNA encodes the entire protein of 421-amino acids including a 25-amino acid leader peptide and a 396-amino acid mature polypeptide. The identity of the medium chain acyl-CoA dehydrogenase clone was confirmed by matching the amino acid sequence predicted from the cDNA to the NH2-terminal and nine internal tryptic peptide sequences derived from pure rat liver medium chain acyl-CoA dehydrogenase. The calculated molecular masses of the precursor medium chain acyl-CoA dehydrogenase, the mature medium chain acyl-CoA dehydrogenase, and the leader peptide are 46,600, 43,700, and 2,900 daltons, respectively. The leader peptide contains five basic amino acids and only one acidic amino acid; thus, it is positively charged, overall. Cysteine residues are unevenly distributed in the mature portion of the protein; five of six are found within the NH2-terminal half of the polypeptide. Comparison of medium chain acyl-CoA dehydrogenase sequence to other flavoproteins and enzymes which act on coenzyme A ester substrates did not lead to unambiguous identification of a possible FAD-binding site nor a coenzyme A-binding domain. The sequencing of other homologous acyl-CoA dehydrogenases will be informative in this regard.

Acyl-CoA Dehydrogenase↗

Purification and properties of short chain acyl-CoA, medium chain acyl-CoA, and isovaleryl-CoA dehydrogenases from human liver.

Short chain acyl-CoA (SCA), medium chain acyl-CoA (MCA), and isovaleryl-CoA (IV) dehydrogenases were purified to homogeneity from human liver using ammonium sulfate fractionation followed by DEAE-Sephadex A-50, hydroxyapatite, Matrex Gel Blue A, agarose-hexane-CoA, and Bio-Gel A-0.5 column chromatographies. The specific activities of the final preparations were enriched 507-, 750-, and 588-fold over those from the second ammonium sulfate fractionation step. The native molecular weights were estimated to be 168,000, 178,000, and 172,000, respectively, by gel filtration. Each of them exhibited, on sodium dodecyl sulfate/polyacrylamide gel electrophoresis, a single protein band with molecular weights of 41,000, 44,000, and 42,000, respectively, indicating a homotetrameric structure. UV/visual spectra, fluorescence spectra, and other evidence indicated that each contains 1 mol of FAD per subunit. They all utilized electron transfer flavoprotein (ETF) or phenazine methosulfate (PMS) as an electron acceptor. The products of SCA dehydrogenase/butyryl-CoA, MCA dehydrogenase/octanoyl-CoA, and IV dehydrogenase/isovaleryl-CoA reactions were identified as crotonyl-CoA, 2-octenoyl-CoA, and 3-methylcrotonyl-CoA, respectively, using gas chromatography. Kinetic parameters Vappmax and Kappm) of these enzymes for various acyl-CoA substrates, as well as Kappm values for ETF and PMS are presented. In general, the substrate specificities of human SCA, MCA, and IV dehydrogenases are slightly less stringent than those of their rat counterparts and resemble those of their bovine and porcine counterparts. The pattern of substrate specificity for these enzymes determined using ETF as electron acceptor significantly differed from that determined using PMS. All of them were severely inhibited by (methylenecyclopropyl)acetyl-CoA.

Acyl-CoA Dehydrogenase↗

Substrate stereochemistry of 2-methyl-branched-chain acyl-CoA dehydrogenase: elimination of one hydrogen each from (pro-2S)-methyl and alpha-methine of isobutyryl-CoA.

Dehydrogenation of (2S)-[3-13C]isobutyryl-CoA was carried out in vitro using 2-methyl-branched-chain acyl-CoA dehydrogenase purified from rat liver mitochondria. The product was subsequently hydrated by the addition of bovine crotonase. The resulting 3-hydroxyisobutyric acid was predominantly enriched with 13C at the beta-hydroxy position as determined as a methyl ester using electron ionization-gas chromatography-mass spectroscopy. This finding indicates that isobutyryl-CoA is dehydrogenated stereospecifically at the (pro-2S)-methyl and alpha-methine groups to form methacrylyl-CoA, which is later hydrated with the addition of hydrogen on the same side of the molecule from which it was subtracted to produce 3-hydroxyisobutyryl-CoA.

Acyl Coenzyme A↗

Echocardiographic evaluation of verapamil in Friedreich's ataxia.

Nine patients with hypertrophic cardiomyopathy associated with Friedreich's ataxia were treated with the calcium antagonist verapamil, which is known to reduce myocardial hypertrophy and improve diastolic function in patients with idiopathic hypertrophic cardiomyopathy. Daily oral doses of 7 mg/kg were given for a mean (SD) of 24 (8) months. M mode echocardiography performed at the start of the study and at the end of follow up showed no significant difference between the treated group and an untreated control group of nine patients. Verapamil produced no changes in left ventricular wall thickness, mass index, left ventricular internal diameter, fractional shortening, peak normalised lengthening rate, peak rate of septal and posterior wall thinning, and time from minimum ventricular cavity dimension to mitral valve opening. Myocardial calcium overload has been suggested as a cause of cardiac disease in Friedreich's ataxia; however, verapamil had no beneficial effect on these patients with established myocardial hypertrophy.

Adolescent↗

Glutamate dehydrogenase in olivopontocerebellar atrophies: leukocytes, fibroblasts, and muscle mitochondria.

Glutamate dehydrogenase (GDH) activity was 68% of control values in leukocyte homogenates of 11 patients with dominant olivopontocerebellar atrophies (OPCA) and 46% in muscle mitochondria of 4 patients with dominant OPCA. In three patients with recessive OPCA and in one sporadic patient, muscle GDH was lower than in controls. However, muscle GDH activity was normal in one of two dominant patients in the same family and decreased in the other, and patients' activities overlapped with lower control values. Plasma glutamate levels were significantly higher in dominant patients than in controls after glutamate challenge. GDH activity may be partially altered at the mitochondrial level in a subgroup of OPCA patients.

Brain Diseases↗

Brainstem auditory-evoked responses and clinical picture in a one year follow-up of 18 patients with Friedreich ataxia.

Brainstem auditory-evoked responses (BAER) and behavior audiometry were evaluated on 18 patients with Friedreich ataxia. Behavior audiometry showed a normal pure tone test, normal performance intensity and phonetically balanced functions in all patients. BAER were abnormal in all patients. The data obtained show a good correlation between BAER and clinical picture and suggest that BAER could be useful in monitoring the clinical condition of FA patients.

Adolescent↗

An approach using lecithin treatment for olivopontocerebellar atrophies.

A therapeutic trial with two different lecithins, with 32 and 7% phosphatidylcholine respectively, was performed for 3 months on 11 patients with clinical diagnosis of dominant, recessive and sporadic olivopontocerebellar atrophies. The correlation between plasma choline levels and the clinical picture shows a clinical worsening with very high choline levels and a slight improvement with smaller increases of plasma choline levels. The possible role in these disorders of phosphatidylcholine and linoleic acid - both present in lecithin - is discussed, with relationship to these findings.

Adult↗

Electromyography and nerve conduction study in autosomal dominant olivopontocerebellar atrophy.

Electromyographic examination and studies of motor and sensory conduction velocities were performed in 11 patients with a presumptive diagnosis of olivopontocerebellar atrophy with autosomal dominant transmission. Peripheral nervous system involvement was shown in eight. In two patients with early onset of disease, electrophysiological alterations clearly pointed to severe axonal degeneration, whereas in six they were compatible with slight demyelination.

Action Potentials↗

Systemic carnitine deficiency: clinical, biochemical, and morphological cure with L-carnitine.

A 20-year-old woman had systemic carnitine deficiency. Biochemical studies of cultured fibroblasts, skeletal muscle mitochondria, and fluids showed no evidence of other disease that might deplete tissue carnitine stores. Carnitine supplementation produced a dramatic improvement in her clinical condition: she gained weight and strength and recovered brain function, which had deteriorated slightly after repeated episodes of encephalopathy. Lipid droplets disappeared from skeletal muscle and plasma, and muscle carnitine content rose from low to normal values. On treatment, she excreted less carnitine than controls. This form of systemic carnitine deficiency may be due to defective carnitine biosynthesis.

Acids↗

[The role of the intestine in the pathogenesis and treatment of multiple organ failure].

Infection and sepsis remain major causes of death in medical and surgical services, despite the availability of potent antibiotics, aggressive surgery and close monitoring of patients in intensive-care units. Actually the terminology to define this type of events in multiple organ failure: we considered the role of intestine in its pathogenesis and its management.

Animals↗