Automated and manual direct methods for the determination of urea in blood or serum are described. These methods determine urea by the colored product formed when urea, in relatively weak acid solution, reacts with diacetyl monoxime in the presence of thiosemicarbazide and ferric ion. Results are compared with those obtained by urease conversion of urea to ammonia and measurement of the ammonia...

Positron emission tomography (PET) was applied to the measurement of myocardial perfusion using the perfusion tracer 13N-labeled ammonia. 13N ammonia was delivered intravenously to 13 healthy volunteers both at rest and during supine bicycle exercise. Dynamic PET imaging was obtained in three cross-sectional planes for 10 minutes commencing with each injection. The left ventricle was divided in...

OBJECTIVE To assess energy depletion in skeletal muscle in patients with congestive heart failure by measuring blood purine metabolites during exercise and, at the same time, determine the implications of the ammonia response to exercise in these patients. SETTING Tottori University Hospital, Yonago, Japan. PATIENTS 49 heart failure patients (New York Heart Association (NYHA) grades I-III) ...

A study was conducted in a completely randomized design to evaluate the performance, excreta characteristics, and some blood nitrogen metabolite concentrations of 28-d-old male broilers fed 4 experimental diets in which CP was decreased in a stepwise manner from 23 to 17%. The other 4 diets were formulated to have 19 and 17% CP, in which 2 of them contained an additional 10% of particular essen...

BACKGROUND Newborns with inborn errors of metabolism often present with hyperammonaemic coma, requiring prompt diagnosis and specific medical therapy, nutritional support and efficient toxin removal. Little information regarding the efficacy and safety of continuous venovenous haemodialysis (CVVHD) as an option for extracorporal ammonia detoxification in children is available. METHODS Twenty-...

To the Editor: I have read the paper by Phelps, Hoffman, and Raybaud "Factors Which Affect Cerebral Uptake and Retention of NH3" (Stroke 8: 694, 1977) with considerable interest, because of my own concern with cerebral ammonia metabolism. There are several questions that I would like to ask concerning their paper. What was the concentration of the ammonia in the test bolus? If it was 10 moles p...

The aim of this study was to determine the differences in concentrations of various metabolites between blood and plasma, and their implications for the measurement of portal net fluxes in ewes. A wide range of concentrations of metabolites in arterial and portal blood was induced by submitting three ewes to three different levels of intake. Plasma measurements underestimated the portal drained...