Ureases display biological effects independent of enzymatic activity: Is there a connection to diseases caused by urease-producing bacteria?

Ureases are enzymes from plants, fungi and bacteria that catalyze the hydrolysis of urea to form ammonia and carbon dioxide. While fungal and plant ureases are homo-oligomers of 90-kDa subunits, bacterial ureases are multimers of two or three subunit complexes. We showed that some isoforms of jack bean urease, canatoxin and the classical urease, bind to glycoconjugates and induce platelet aggregation. Canatoxin also promotes release of histamine from mast cells, insulin from pancreatic cells and neurotransmitters from brain synaptosomes. In vivo it induces rat paw edema and neutrophil chemotaxis. These effects are independent of ureolytic activity and require activation of eicosanoid metabolism and calcium channels. Helicobacter pylori, a Gram-negative bacterium that colonizes the human stomach mucosa, causes gastric ulcers and cancer by a mechanism that is not understood. H. pylori produces factors that damage gastric epithelial cells, such as the vacuolating cytotoxin VacA, the cytotoxin-associated protein CagA, and a urease (up to 10 percent of bacterial protein) that neutralizes the acidic medium permitting its survival in the stomach. H. pylori whole cells or extracts of its water-soluble proteins promote inflammation, activate neutrophils and induce the release of cytokines. In this paper we review data from the literature suggesting that H. pylori urease displays many of the biological activities observed for jack bean ureases and show that bacterial ureases have a secretagogue effect modulated by eicosanoid metabolites through lipoxygenase pathways. These findings could be relevant to the elucidation of the role of urease in the pathogenesis of the gastrointestinal disease caused by H. pylori.

Environmental factors affecting urease production by penicillium funiculosum 258

Maximum urease synthesis was obtained by the fungus Penicillium funiculosum 258 when grown on medium containing urea as sole nitrogen source at concentration of 0.5% and 1% glucose as carbon source adjusted to pH 6 and inoculated with 10% previously prepared inoculum in shaked culture with 4: 1 air medium ratio for 3 days incubation. Urease production by the tested fungus required addition of thiamine and biotin to the culture medium at concentrations of 0.001%. The enzyme activity of the formulated medium increased from 15.3 mu/ml to 29.65% mu/ml and the enzyme productivity also increased from 3.31 to 8.97 mu/mg dry weight

Upper urinary tract stones & Ureaplasma urealyticum.

Extensive culture of stones and of pre-operative and renal pelvic urine for isolation of bacteria and Ureaplasma urealyticum were performed in 70 patients of nephrolithiasis. Stones were subjected to biochemical analysis and scanning electron microscopy. Micro-organisms were isolated from 33 (47%) of 70 renal stones. Of the 38 species of micro-organisms isolated, 14 were urea-splitting (U. urealyticum 2; Klebsiella pneumoniae 8; Morganella morganii 1; Acinetobacter spp 3) and 24 were nonurea splitting. U. urealyticum was cultured from the renal stones of two patients. Pelvic urine, unlike voided urine did reflect the bacteriology of the stone. Biochemically, 55 stones (79%) were calcium oxalate phosphate stones, 10 (14%) were calcium oxalate stones and 5 (7%) were uric acid stones. None of the stones were found to be of struvite composition. These data suggest that infection stones are uncommon in this part of the country. Further, infection of renal stones with fastidious organisms like U. urealyticum and multi-drug resistant bacteria necessitate their removal to ensure complete cure.

La importancia clínica de Helicobacter pylori y el diagnóstico de laboratorio de las enfermedades que ocasiona al humano / The importance of clinic diagnostic of Helicobacter pylory and diseases cause

H. pylori es una bacteria curva o helicoidal que se establece y multiplica en la mucosa gástrica ÄÄbasándose en algunos de sus diversos factores de patogenicidadÄÄ y, aunque no invade los tejidos, provoca la progresiva degradación de la capa de moco que protege al epitelio estomacal, exponiéndolo a la acción lesiva del ácido clorhídrico, aún cuando éste no alcanza las concentraciones comunes, ya que el microorganismo también afecta a las células parietales (que son las responsables de la liberación del HCI). De esa manera, H. pylori promueve la ocurrencia de las gastritis y las úlceras gástricas, aunque también se acepta que desempeña un importante papel en las úlceras duodenales, e inclusive, se le relaciona con la aparición de adenocarcinoma gástrico. El diagnóstico de laboratorio de las gastritis y las úlcera gástricas contempla métodos invasivos y no invasivos, considerando que, en el caso de los primeros, las muestras apropiadas son las biopsias obtenidas mediante endoscopía, en tanto que, los segundos, se basan en la detección-cuantificativa de anticuerpos séricos anti-H. pylory

La microtécnica en el diagnóstico bacteriológico / Microtechnic in bacteriological diagnosis

Por primera vez en nuestro medio, se prueba un método microtécnico para la detección de ureasa producida por microorganismos entéricos gramnegativos, procedentes de productos patológicos de origen humano, con el cual es posible realizar esta investigación bioquímica a 96 cepas bacterianas diferentes a la vez, en un tiempo máximo de 60 minutos y un área de incubación mínima. Se investigaron 1.940 cepas. Al comparar los resultados de la microtécnica con los obtenidos por el método convencional, se observó una coincidencia en el 100%