1/4. pyruvate carboxylase deficiency: clinical and biochemical response to anaplerotic diet therapy.A six-day-old girl was referred for severe hepatic failure, dehydratation, axial hypotonia, and both lactic acidosis and ketoacidosis. biotin-unresponsive pyruvate carboxylase deficiency type B was diagnosed. Triheptanoin, an odd-carbon triglyceride, was administrated as a source for acetyl-CoA and anaplerotic propionyl-CoA. Although this patient succumbed to a severe infection, during the six months interval of her anaplerotic and biochemical management, the following important observations were documented: (1) the immediate reversal (less than 48 h) of major hepatic failure with full correction of all biochemical abnormalities, (2) on citrate supplementation, the enhanced export from the liver of triheptanoin's metabolites, namely 5 carbon ketone bodies, increasing the availability of these anaplerotic substrates for peripheral organs, (3) the demonstration of the transport of C5 ketone bodies-representing alternative energetic fuel for the brain-across the blood-brain barrier, associated to increased levels of glutamine and free gamma-aminobutyric acid (f-GABA) in the cerebrospinal fluid. Considering that pyruvate carboxylase is a key enzyme for anaplerosis, besides the new perspectives brought by anaplerotic therapies in those rare pyruvate carboxylase deficiencies, this therapeutic trial also emphasizes the possible extended indications of triheptanoin in various diseases where the citric acid cycle is impaired.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
2/4. Pyruvate-carboxylase deficiency with urea cycle impairment.We report a case of pyruvate-carboxylase deficiency (EC 6.4.1.1, McKusick 26615) with neonatal onset of lactic acidosis, hyperammonemia, and citrullinemia. The patient developed signs of severe liver damage and died at 13 days of age after increasing metabolic acidosis and severe bleedings. The pyruvate-carboxylase activity in fibroblasts was less than 1% of controls, but normal activities of propionyl-CoA carboxylase (EC 6.4.1.3) and 3-methylcrotonyl-CoA carboxylase (EC 6.4.1.4) were found. To prepare for early prenatal diagnosis of pyruvate-carboxylase deficiency, the activity of the enzyme has been measured in chorionic villus samples.- - - - - - - - - - ranking = 4keywords = cycle (Clic here for more details about this article) |
3/4. The clinical and biochemical implications of pyruvate carboxylase deficiency.A 10 month old female infant was evaluated for severe lactic acidosis. Clinically she was well nourished and had a substantial amount of adipose tissue despite recurrent episodes of acidosis. Her psychomotor development was retarded, her movements were dystonic and generalized seizures punctuated her course. Metabolic abnormalities included elevated blood concentrations of lactate, pyruvate, beta-hydroxybutyrate, acetoacetate, alanine, proline and glycine, decreased blood concentrations of glutamine, aspartate, valine and citrate, and intermittent elevations of serum cholesterol. A trial on a high-fat diet worsened the clinical condition and intensified the ketoacidosis and hyperalaninemia. Analysis of hepatic tissue obtained by open biopsy revealed increased concentrations of lactate, alanine, acetyl-CoA and other short-chain acyl-CoA esters, and decreased concentrations of oxaloacetate, citrate, alpha-ketoglutarate, malate and aspartate. The blood and tissue metabolic perturbations reflected a deficiency of hepatic pyruvate carboxylase. The apparent Km of hepatic citrate synthase for oxaloacetate was 4.6 micrometer. Calculated tissue oxaloacetate concentrations were 0.50--0.84 micrometer suggesting that tricarboxylic acid cycle activity was severely limited by the decreased availability of this substrate. An iv glucose tolerance test resulted in the paradoxical synthesis of ketone bodies. This observation, coupled with the intermittent hypercholesterolemia and the increased tissue acetyl-CoA concentrations, suggests that pyruvate carboxylase is important in modulating the fractional distribution of intracellular acetyl-CoA between the tricarboxylic acid cycle, the beta-hydroxy-beta-methyl-glutaryl-CoA cycle (and the synthesis of cholesterol and ketone bodies), and fatty acid synthesis. Treatment in future cases might be directed toward increasing tissue concentrations of oxaloacetate.- - - - - - - - - - ranking = 3keywords = cycle (Clic here for more details about this article) |
4/4. Progressive infantile poliodystrophy (Alpers' disease) with a defect in citric acid cycle activity in liver and fibroblasts.We present the case history of a boy, who died at the age of 3 1/2 years after a rapidly progressive neurologic disorder, characterized by psychomotor retardation, hypotonia, hemiparesis, seizures and myoclonic contractions. Histopathologic studies showed slight lipid storage in liver. autopsy showed the characteristic features of progressive infantile poliodystrophy (Alpers' disease); ultrastructural examination showed an increased density of mitochondria in cerebral gray matter. Biochemical studies in leukocytes, cultured fibroblasts and liver indicated a deficiency in the citric acid cycle between succinate and fumarate; this deficiency was not present in muscle tissue. This study supports the view that progressive infantile poliodystrophy is associated with abnormalities in pyruvate metabolism and/or in cell mitochondria.- - - - - - - - - - ranking = 5keywords = cycle (Clic here for more details about this article) |