Liver mitochondria from the desert tortoise Gopherus agassizii and the Texas tortoise G. berlandieri contain glutamine synthetase, the enzyme used by birds and higher reptiles to detoxify ammonia generated intramitochondrially during amino acid catabolism. Tortoise mitochondria also contain carbamyl phosphate synthetase-I and ornithine transcarbamylase, the enzymes used by mammals for this purp...

The sparse fur (spf) mutant mouse is a model for human X-linked ornithine transcarbamylase (OTC) deficiency. Human OTC cDNA placed under transcriptional control of the mouse OTC promoter was microinjected into fertilized oocytes of spf mice. Two founder lines of transgenic mice were phenotypically and biochemically corrected for OTC deficiency by the expression of the human gene at high levels ...

Ornithine transcarbamylase deficiency (OTCD) is an X-linked, inherited condition within the urea cycle characterized by failure of ammonia detoxification and urea formation. This may lead to hyperammonemic encephalopathy that, if uncontrolled, results in brain injury and death. Individuals susceptible to this disorder are at risk for hyperammonemic crises if a catabolic state is precipitated. W...

BACKGROUND Hyperammonemic encephalopathy is a potentially fatal condition that may progress to irreversible neuronal damage and is usually associated with liver failure or portosystemic shunting. However, other less common conditions can lead to hyperammonemia in adults, such as fibrolamellar hepatocellular carcinoma. Clinical awareness of hyperammonemic encephalopathy in patients with normal l...

SUMMARY Urea cycle defect is an inborn error of ammonium metabolism caused by a deficient activity of the enzymes involved in urea synthesis. Localized short-TE proton MR spectroscopy, performed in two infants who had citrullinemia and ornithine transcarbamylase deficiency, respectively, showed a prominent increase of glutamine/glutamate and lipid/lactate complex in both cases. N-acetylaspartat...

We developed a new technique that monitors metabolic competency in female heterozygotes for ornithine transcarbamylase deficiency (OTCD). The method uses mass spectrometry to measure conversion of (15)NH4Cl to [15N]urea and [5-(15)N]glutamine following an oral load of (15)NH4Cl. We found that heterozygotes converted significantly less NH3 nitrogen to urea, with this difference being particularl...

Congenital ornithine transcarbamylase deficiency (OTCD, OMIM 311250, Xp21.1) in humans results in hyperammonaemia with subsequent neurological symptoms including hypotonia, seizures and mental retardation. At the age of 3 years a hyperkinetic-hyperactive behaviour disorder of unknown origin was diagnosed in our female patient. The girl, ultimately diagnosed as having OTCD presented at the age o...

In this case report we describe a 67-year-old male, admitted to the ICU with pneumonia who unexpectedly developed a fatal coma due to hyperammonaemia. At postmortem the diagnosis late-onset ornithine transcarbamylase deficiency was made. The non-specific clinical presentation, the rapid deterioration and incidentally the fatal outcome all underline the importance of recognition and knowledge of...