Accurate quantization of urea is very essential for precise dialysis therapy in the case of kidney failure. In the present paper we report a new colorimetric method for urea quantification using urease as a probe. The method is based on the reaction between bispyrazolone and ammonia released by the urease catalyzed hydrolysis of urea. A linear relationship of the absorbance at 540 nm of the pro...

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 ...

Helicobacter pylori strain J166 recovered from experimentally inoculated rhesus monkeys had up to a 250-fold-increased urease activity over that before inoculation. This was found to result from the selection of urease positive J166 clones from a heterogeneous inoculum, which was predominantly urease negative due to a 1-bp insertion in the ureA gene. These results confirm the importance of urea...

Proteus mirabilis, a cause of complicated urinary tract infection, expresses urease when exposed to urea. While it is recognized that the positive transcriptional activator UreR induces gene expression, the levels of expression of the enzyme during experimental infection are not known. To investigate in vivo expression of P. mirabilis urease, the gene encoding green fluorescent protein (GFP) wa...

Jack bean urease catalyzes the decomposition of urea into ammonia, which in turn increases the pH of the surrounding medium. Based on these two properties, we have investigated the antitumor effects of urease in vitro and in vivo on human lung and breast cancer cell lines either by the enzyme itself or in combination with other chemotherapeutic drugs. First, through the generation of toxic ammo...

Ureaplasma urealyticum is a pathogenic ureolytic mollicute which colonizes the urogenital tracts of humans. A genetic polymorphism between the two biotypes of U. urealyticum at the level of the urease genes was found. The urease gene cluster from a biotype 1 representative of U. urealyticum (serotype I) was cloned and sequenced. Seven genes were found, with ureA, ureB, and ureC encoding the str...

The observation was made some 6 years ago that chickens were not poisoned by the parenteral injection of large quantities of crystalline urease, unless urea was also injected (1). However, rabbits were killed after urease was injected when the blood ammonia nitrogen reached a value of 5 mg. per 100 cc. (2). These observations offer sufficient evidence to make many of the values reported for ure...

To infect a susceptible host, the gastrointestinal pathogen Yersinia enterocolitica must survive passage through the acid environment of the stomach. In this study, we showed that Y. enterocolitica serotype O8 survives buffered acidic conditions as low as pH 1.5 for long periods of time provided urea is available. Acid tolerance required an unusual cytoplasmically located urease that was activa...

This study investigated the influence of urease-positive non-Helicobacter pylori bacteria on the results of a urea breath test (UBT) to evaluate the diagnostic utility of a UBT using film-coated [(13)C]urea tablets. The UBT was performed in 102 patients treated with a proton pump inhibitor and antibiotics for the eradication of H. pylori. Urease-producing bacteria other than H. pylori were isol...