BACKGROUND Several modifications of the 13C-urea breath test have been published. For reasons of cost efficiency and practicability, the urea dose and measurement duration should be reduced while still maintaining excellent diagnostic accuracy. AIMS To establish a validated simple protocol for the urea breath test with 50 mg 13C-urea and to compare this protocol with the conventional urea bre...

Improper use of urea may cause environmental pollution through NH3 volatilization and NO3 (-) leaching from urea. Clinoptilolite zeolite and compost could be used to control N loss from urea by controlling NH4 (+) and NO3 (-) release from urea. Soil incubation and leaching experiments were conducted to determine the effects of clinoptilolite zeolite and compost on controlling NH4 (+) and NO3 (-...

UNLABELLED Urea and NaCl are elevated in the renal inner medulla. We now find that a high concentration of urea or NaCl increases reactive oxygen species (ROS) in mouse renal inner medullary (mIMCD3) cells in culture. Previously, high NaCl, but not high urea, was found to cause DNA double-strand breaks. We now tested whether high urea or NaCl causes oxidative damage to DNA or cellular proteins....

The rate at which urea enters the body pool of urea in sheep was investigated using isotope dilution techniques. Both single injection and constant infusion of carbon-14 urea were used. Urea excretion rates were calculated by measuring the urea in urine collected from a catheter in the bladder. Urea entry and excretion rates were measured in sheep fed rations containing 3.5, 9, 17 and 27% crude...

Marine elasmobranch fishes maintain high urea concentrations and therefore must minimize urea loss to the environment in order to reduce the energetic costs of urea production. Previous studies have identified a facilitated urea transporter in the kidney of the dogfish. We examined mechanisms of urea transport in the kidney of the little skate Raja erinacea using an isolated brush-border membra...

Urea kinetics were measured in normal women aged 22-34 years at weeks 16, 24 and 32 on either their habitual protein intake (HABIT) or a controlled intake of 60 g protein/d (CONTROL), using primed-intermittent oral doses of [15N15N]urea and measurement of plateau enrichment in urinary urea over 18 h (ID) or a single oral dose of [15N15N]urea and measurement of enrichment of urea in urine over t...

a phosgene-free synthesis of symmetrical n,n'-disubstituted urea by the reaction of aromatic and aliphatic primary amines and urea promoted by  microwave irradiation in the presence of a suitable energy-transfer solvent such as n-n-dimethylacetamide is described.

Although urea transport is receiving increased attention in mammalian systems, very little is known about urea transport in fish tissues. This study examined mechanisms of urea transport in red blood cells and hepatocytes from the lesser spotted dogfish (Scyliorhinus canicula), Atlantic stingray (Dasyatis sabina), turbot (Scopthalmus maximus), redfish (Scianops ocellatus), gulf toadfish (Opsanu...

14C and 15N isotopes of urea were infused intravenously into rabbits for 6-8 h in order to measure urea synthesis and the extent of degradation in the digestive tract. The results indicate that 0.62 of the urea flux was excreted in the urine and that re-incorporation of urea-N following hydrolysis in the gut represented 0.3 of the urea synthesis rate. Sampling of metabolites from the caecum by ...