Ornithine decarboxylase (ODC) is a key enzyme in the biosynthetic pathway of polyamines and catalyzes the decarboxylation of ornithine to produce putrescine. Inhibition of ODC activity is a potential approach for the prevention and treatment of many diseases including cancer, as the expression levels and the activities of ODC in many abnormal cells and tumor cells are generally higher than those of normal cells. The discovery and evaluation of ODC inhibitors rely on the monitoring of the reaction processes catalyzed by ODC. There are several commonly used methods for analyzing the activity of ODC, such as measuring the yield of putrescine by high performance liquid chromatography, or quantifying the yield of isotope labelled carbon dioxide. However, the cumbersome operation and cost of these assays, as well as the difficulty to achieve high-throughput and real-time detection, hampered their applications. In this work, we optimized a real-time label-free method for analyzing the activity of ODC based on the macromolecule cucurbit[6]uril (CB6) and a fluorescent dye, DSMI (trans-4-[4-(dimethylamino) styryl]-1-methylpyridinium iodide). Finally, the optimized method was used to determine the activities of different ODC inhibitors with different inhibition mechanisms.
Bridged-Ring Compounds ; Imidazoles ; Ornithine ; Ornithine Decarboxylase ; Ornithine Decarboxylase Inhibitors ; Putrescine

OBJECTIVETo analyze the clinical features, metabolic profiling and gene mutations of patients with ornithine transcarbamylase deficiency (OTCD) and explore the molecular pathogenesis of OTCD in order to provide a solution for molecular diagnostics and genetic counseling.

METHODSClinical data of 3 neonates were analyzed. The amino acids level in blood was analyzed with mass spectrum technology. PCR was used to amplify all the 10 exons of OTC gene. The PCR products were directly sequenced to detect the mutations.

RESULTSAll of the 3 cases had neonatal onset and showed poor reaction, feeding difficulty, convulsion and neonatal infection. Citrulline levels were significantly decreased. Case 1 had a missense mutation of Y183C. Case 2 showed a missense mutation of V339G in exon 10. And a missense mutations of W332S in exon 9 was detected in case 3.

CONCLUSIONAnalysis of OTC gene sequences can be used for the diagnosis of OTCD and screening of asymptomatic carriers. Mutation analysis is important for prenatal diagnosis of individuals with a positive family history and genetic counseling. The V339G and W332S mutations have been discovered for the first time. Patients with such mutations may have onset of the disease during neonatal period.

Humans ; Male ; Mutation ; Ornithine Carbamoyltransferase ; genetics ; Ornithine Carbamoyltransferase Deficiency Disease ; genetics ; metabolism

Ornithine transcarbamylase (OTC) deficiency is well known as the most common inherited disorder of the urea cycle, and 1 of the most common causes of hyperammonemia in newborns. We experienced a case of a 3-day-old boy with OTC deficiency who appeared healthy in the first 2 days of life but developed lethargy and seizure soon afterwards. His serum ammonia level was measured as >1700 microg/dL (range, 0 to 45 microg/dL). Continuous renal replacement therapy (CRRT) in the mode of continuous venovenous hemodiafiltration was immediately applied to correct the raised ammonia level. No seizure occurred after the elevated ammonia level was reduced. Therefore, CRRT should be included as 1 of the treatment modalities for newborns with inborn errors of metabolism, especially hyperammonemia. Here, we report 1 case of successful treatment of hyperammonemia by CRRT in a neonate with OTC deficiency.
Ammonia ; Hemodiafiltration ; Humans ; Hyperammonemia ; Infant ; Infant, Newborn ; Lethargy ; Metabolism, Inborn Errors ; Ornithine ; Ornithine Carbamoyltransferase ; Ornithine Carbamoyltransferase Deficiency Disease ; Renal Replacement Therapy ; Seizures ; Urea

OTC deficiency is an X-linked disorder in which the synthesis of urea is impaired. OTC catalyzes the synthesis of citrulline from carbamyl phosphate and ornithine. Complete or partial deficiencies of this enzyme may lead to Reye syndrome like picture such as encephalopathy, hepatic dysfunction, hyperammonemia, etc. We recently had a case that was presented as recurrent Reye syndrome, and was effectively treated with hemodialysis, arginine, sodium benzoate, etc. This report describes an experience in treating this condition with review of available literature.
Arginine ; Carbamyl Phosphate ; Citrulline ; Hepatic Encephalopathy ; Hyperammonemia ; Ornithine Carbamoyltransferase Deficiency Disease ; Ornithine Carbamoyltransferase* ; Ornithine* ; Renal Dialysis ; Reye Syndrome ; Sodium Benzoate ; Urea

OBJECTIVETo detect potential mutations of OTC gene in a male infant affected with ornithine transcarbamylase deficiency.

METHODSGenomic DNA were isolated from peripheral blood samples of family members and 100 healthy individuals. Potential mutations of the 10 exons of OTC gene were screened with PCR and Sanger sequencing.

RESULTSA homozygous missense mutation c.917G>C in exon 9, which results in p.R306T, was identified in the infant. Sequencing of the mother and two female members of the family indicated a heterozygous status for the same mutation. The same mutation was not found in other members of the family and 100 healthy controls.

CONCLUSIONA missense mutation c.917G>C in the OTC gene is responsible for the pathogenesis of the disease. Identification of the mutation can facilitate prenatal diagnosis and genetic counseling for the family.

Computational Biology ; Female ; Humans ; Male ; Mutation ; Ornithine Carbamoyltransferase ; genetics ; Ornithine Carbamoyltransferase Deficiency Disease ; diagnosis ; genetics ; Sequence Analysis, DNA

OBJECTIVETo analyze the clinical and genetic characteristics of three children with ornithine carbamoyltransferase deficiency(OTCD), and to provide a practical method for gene diagnosis and genetic counseling of the disease.

METHODSAll exons of the ornithine carbamoyltransferase (OTC) gene were screened by polymerase chain reaction-DNA direct sequencing in the three OTCD patients.

RESULTSOne patient firstly presented as vomiting at 6 month of age. A missense mutation of T262I was detected. His mother had the same mutation without any clinical symptoms. The second patient presented as restlessness, and had a missense mutation of R277W. Gene analysis of his parents was not available. The third patient presented as neonatal lethargy, harbored a missense mutation of I172M. His mother had the same mutation without any clinical symptoms.

CONCLUSIONGene mutation analysis is a feasible way for diagnosing OTCD. Patients with I172M mutation present symptom early, while those with T262I and R277W mutations manifest symptoms later. Gene mutation analysis will be important for asymptomatic and prenatal diagnosis and genetic counseling.

Base Sequence ; Child ; Exons ; Humans ; Infant ; Infant, Newborn ; Male ; Mutation ; genetics ; Ornithine Carbamoyltransferase ; genetics ; Ornithine Carbamoyltransferase Deficiency Disease ; genetics ; pathology

Severe hyperammonemia can occur as a result of inherited or acquired liver enzyme defects in the urea cycle, among which ornithine transcarbamylase deficiency (OTCD) is the most common form. We report a very rare case of a 45-year-old Korean male who was admitted to the intensive care unit (ICU) due to severe septic shock with acute respiratory failure caused by Pneumocystis jiroveci pneumonia. During his ICU stay with ventilator care, the patient suffered from marked hyperammonemia (>1,700 µg/dL) with abrupt mental change leading to life-threatening cerebral edema. Despite every effort including continuous renal replacement therapy and use of a molecular adsorbent recirculating system (extracorporeal liver support-albumin dialysis) to lower his serum ammonia level, the patient was not recovered. The lethal hyperammonemia in the patient was later proven to be a manifestation of acquired liver enzyme defect known as OTCD, which is triggered by serious catabolic conditions, such as severe septic shock with acute respiratory failure.
Ammonia ; Brain Edema ; Humans ; Hyperammonemia* ; Intensive Care Units ; Liver ; Male ; Middle Aged ; Ornithine Carbamoyltransferase Deficiency Disease* ; Ornithine Carbamoyltransferase* ; Ornithine* ; Pneumocystis jirovecii ; Pneumonia ; Renal Replacement Therapy ; Respiratory Insufficiency ; Shock, Septic* ; Urea ; Ventilators, Mechanical

The ornithine aminotransferase (OAT) activity of mouse was found to be highest in the small intestine. The mitochondrial OAT from mouse small intestine was purified to homogeneity by the procedures including heart treatment, ammonium sulfate fractionation, octyl-Sepharose chromatography, and Sephadex G-150 gel filtration. Comparing to the amino acid sequence of mouse hepatic OAT, six N-terminal amino acid residues have been deleted in intestinal OAT. However, the subsequent sequence was identical with that of hepatic OAT. The molecular weights of both intestinal and hepatic OAT were estimated as 46 kDa by SDS-gel electrophoresis and as 92 kDa by gel filtration, indicating that both native OATs are dimeric. Biochemical properties of intestinal OAT, such as molecular weight, pH optimum and K(m) values for L-ornithine and alpha-ketoglutarate, were similar to those of hepatic OAT. However, intestinal OAT was more labile than hepatic OAT to tryptic digestion.
Amino Acid Sequence ; Animal ; Intestine, Small/enzymology* ; Liver/enzymology ; Male ; Mice ; Mice, Inbred ICR ; Molecular Sequence Data ; Molecular Weight ; Ornithine-Oxo-Acid Transaminase/metabolism* ; Ornithine-Oxo-Acid Transaminase/isolation & purification ; Ornithine-Oxo-Acid Transaminase/genetics* ; Tissue Distribution ; Trypsi

Ornithine transcarbamylase (OTC) deficiency is the most common inborn error of urea cycle metabolism; it is inherited in an X-linked manner. The OTC catalyzes the third step of the urea cycle, the conversion of ornithine and carbamyl phosphate to citrulline. Deficiency of OTC leads to the accumulation of ammonia, causing neurological deficits. In most affected hemizygote males, OTC deficiency manifests as hyperammonemic coma that often leads to death in the newborn period, and those who recover from the coma may be neurologically impaired due to the sequelae of the hyperammonemic encephalopathy. In some, late-onset manifestations develop. We report a male neonate with early onset OT deficiency that had apnea and was comatous. On mutation analysis using DNA sequencing after polymerase chain reaction (PCR) amplification of the 10 exons, deletions of 10 bases in codon 285, causing a frame shift was detected in exon 8. The mother and a sister were diagnosed as female carriers. Therefore, genetic counseling and the risk assessment could be provided to the family.
Ammonia ; Apnea ; Carbamyl Phosphate ; Citrulline ; Codon ; Coma ; Diagnosis* ; Exons ; Female ; Genetic Counseling ; Hemizygote ; Humans ; Infant, Newborn ; Male ; Metabolism ; Mothers ; Ornithine Carbamoyltransferase Deficiency Disease* ; Ornithine Carbamoyltransferase* ; Ornithine* ; Polymerase Chain Reaction ; Risk Assessment ; Sequence Analysis, DNA ; Siblings ; Urea

CT and MR appearance of the brain in three children with ornithine transcarbamylase (OTC) deficiency are described. They showed clinical signs of vomiting and convulsion and were diagnosed by measurement of plasma ammonium, amino acids, acid-base balance, and urinary orotic acid levels. CT and MR were performed within one month from the onset of the symptom. CT and MRI demonstrated brain swelling with small ventricles and diffuse low density of white matter, which indicated cerebral hypoperfusion secondary to elevated intracranial pressure. With more prolonged survival hyperammonemia may cause cerebral atrophy. CT and MR appearance in these cases resembled a hypoxic brain damage and this finding should be included in the differential diagnosis.
Acid-Base Equilibrium ; Amino Acids ; Ammonium Compounds ; Atrophy ; Brain ; Brain Edema ; Child ; Diagnosis, Differential ; Humans ; Hyperammonemia* ; Hypoxia, Brain ; Intracranial Hypertension ; Magnetic Resonance Imaging* ; Ornithine Carbamoyltransferase Deficiency Disease* ; Ornithine Carbamoyltransferase* ; Ornithine* ; Orotic Acid ; Plasma ; Seizures ; Vomiting