It has been previously demonstrated that the hepatic level of each enzyme concerned with the biosynthesis of urea in the rat, i.e. carbamyl phosphate synthetase, ornithine transcarbamylase, argininosuccinate synthetase, argininosuccinase, and arginase (see Ratner (1) and Cohen and Brown (2) for discussions of the enzymatic steps of urea biosynthesis and general problems of urea synthesis), bear...

Soybean is traditionally grown in soil, where root symbiosis with Bradyrhizobium japonicum can supply nitrogen (N), by means of bacterial fixation of atmospheric N2. Nitrogen fertilizers inhibit N-fixing bacteria. However, urea is profitably used in soybean cultivation in soil, where urease enzymes of telluric microbes catalyze the hydrolysis to ammonium, which has a lighter inhibitory effect c...

Objective. To report an unusual cause of coma in an adult. Design. Case report. Setting. University teaching hospital. Patient. A previously healthy 53-year-old man initially presented with altered mental status and progressed to coma. He was found to be substantially hyperammonemic and did not improve with lactulose therapy and continuous venovenous hemodialysis. Results. Biochemical testing r...

Valproic acid is used in the treatment of multiple disorders. Adverse effects from valproic acid include hepatotoxicity, hypotension, metabolic acidosis, and decreased mental status. Valproic acid also causes hyperammonemia. Many physicians assume that this is due to a supratherapeutic valproic acid concentration; when in fact, it can occur with therapeutic valproic acid concentrations. This is...

Ornithine transcarbamylase deficiency (OTCD) is an X-linked inborn defect of metabolism of the urea cycle, which causes hyperamonemia. Mutations of the OTC gene have been recognized as the genetic cause underlying the OTC deficiency. The severity of the disease is associated with the type of mutation, leading either to neonatal onset of hyperammonemia or to a later appearance of the disease. Th...

Nickel (Ni) is essential for plants, yet its physiological role is poorly understood. Ni-deficient and Ni-sufficient pecan [Carya illinoinensis (Wangenh.) K. Koch] trees were compared regarding the impact of Ni nutritional status on reduced nitrogen (N) forms present in xylem sap at spring bud break. High performance liquid chromatography (HPLC) of xylem sap of Ni-sufficient trees found organic...

l-Proline concentration is primarily related to the balance of enzymatic activities of proline dehydrogenase [proline oxidase (POX)] and Delta-1-pyrroline-5-carboxylate (P5C) reductase. As a result, P5C plays a pivotal role in maintaining the concentration of proline in body fluids and inborn errors of P5C metabolism lead to disturbance of proline metabolism. Several inborn errors of proline me...