color from ammonia was produced by an additional 5 min of incubation at 37 C. All strains of Proteus, except those of P. inconstans, generated detectable amounts of ammonia (Table 1). None of the Escherichia organisms was urease-positive. These findings were identical with those yielded by the urease technique of Stuart et al. The sensitivity of the Berthelot color reaction permits detection of...

A conductometric urea biosensor based on sol–gel-immobilized urease on a screen-printed inter-digitated array (IDA) electrode has been developed. The screen-printed thick-film IDA electrode has proven to be an excellent conductometric transducer in which the admittance signal was dominated by the conductance signal and the resulting dynamic range was wide enough to be employed for the construct...

Bacterial urease, particularly from Proteus mirabilis, has been implicated as a contributing factor in the formation of urinary and kidney stones, obstruction of urinary catheters, and pyelonephritis. Weekly urine specimens (n = 1,135) from 32 patients, residing at two chronic-care facilities, with urinary catheters in place for greater than or equal to 30 days yielded 5,088 phenotypically and ...

Helicobacter pylori urease is essential for colonization of the gastric mucosa irrespective of whether the stomach is acidic or hypochlorhydric. It has therefore been speculated that the enzyme functions as an adhesin. The aim of this study was to compare the adherence of H. pylori N6 with the adherence of an isogenic urease-negative mutant, strain N6(ureB::TnKm), to gastric cells. Strain N6 or...

Urease is a nickel-containing urea hydrolase involved in nitrogen recycling from ureide, purine, and arginine catabolism in plants. The process of urease activation by incorporation of nickel into the active site is a prime example of chaperone-mediated metal transfer to an enzyme. Four urease accessory proteins are required for activation in Klebsiella aerogenes. In plants urease accessory pro...

The mechanism by which Helicobacter pylori induces apoptosis remains unclear. In a previous study using biopsy samples, we found a significant correlation between the urease activity of an H. pylori strain and the apoptosis level induced by this strain. Therefore, in this study, we investigated whether urease and/or the ammonia generated by urease can induce apoptosis. Human gastric epithelial ...

Two dinickel mimics, [LNi2(DMF)4](ClO4)3 () and [L'Ni2(CH3CN)4](ClO4)3 (), for the active site of urease supported by a disubstituted benzoate polydentate ligand were synthesized and fully characterized, subsequently addition of urea afforded two urea adducts, [LNi2(urea)4](ClO4)3 () and [L'Ni2(urea)4](ClO4)3 ().

1. In the utilization of urea by dairy cattle the first stage is probably the conversion of urea to NH3 in the rumen. Moreover, the urease activity of the rumen ingesta is so great at all times of the day, whatever the time of feeding, and remains so little affected by relatively large apaounts of urea, that all the urea ever likely to be fed, even to a high yielding cow in full lactation, woul...

In connection with other studies in this laboratory (1, 2),’ it became necessary to determine the concentration of urea in the blood of individual new-born rats. In view of the small quantities of blood available and the need for a considerable number of analyses, the calorimetric method developed by Archibald (3) appeared to be particularly suitable. This method is based upon the formation of ...

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...