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PubMed1977

Immunofluorescent localization of urease in the cotyledons of jack bean, Canavalia ensiformis.

Urease has been localized in sections of cotyledons from germinating seeds of jack bean, using FITC-labelled immunoglobulin prepared from urease antiserum raised in rabbits. The complication of lectin binding to the immunoglobulins was resolved by treatment of the sections with specific glycosides. Urease is localized in 2 sites: within the cytoplasm of storage parenchyma cells in spherical granules up to 3 micrometer in diameter, and within the intercellular spaces in spherical granules. Although similar in size, the latter are distinguished from the cytoplasmic granules by the presence of beta-lectin and appear to function as an extracellular lytic compartment or lysosome.

Antibody Specificity↗
PubMed1995

Inhibitory effect of beta-glucosyl-phenolic hydroxamic acids against urease in the presence of microfloral beta-glucosidase.

Three glucosyl-phenolic hydroxamates, 4-O-(beta-D-glucopyranosyl) benzohydroxamic acid, 4-O-(beta-D-glucopyranosyl)hippuric hydroxamic acid, and 3-[4-O-(beta-D-glucopyranosyl)phenyl]propionohydroxamic acid (Glc-PPHA), were hydrolyzed to their corresponding aglycones by beta-glucosidase of intestinal flora of rat without any major adverse hydrolysis in vitro. Inhibitory potency of these glucosyl-hydroxamates on urease was recovered to the same extent as that of the corresponding aglycone hydroxamates by preincubation for 2h with rat intestinal flora. p-Hydroxyphenylpropionohydroxamic acid inhibited noncompetitively jack-bean urease activity and its glucose-ligated form, Glc-PPHA inhibited it competitively. A single oral dose of Glc-PPHA tended to inhibit urease activity in proximal colon contents of rat at 6 h after administration (p = 0.06). After 14C-urea was orally administered to rat, 14CO2 was collected for to measure the ureolysis in vivo. Expired 14CO2 was limited to 40% by a single oral dose of Glc-PPHA during 6 h, and 75% of intestinal ureolysis was repressed during the first 1 h in the breath test.

Animals↗
PubMed1980

Therapy for urolithiasis by hydroxamic acids. III. Urease inhibitory potency and urinary excretion rate of N-acylglycinohydroxamic acids.

Hydroxamic acid, a potent urease inhibitor, having a high urinary excretion rate is expected to be a therapeutic agent for urolithiasis caused by urea-splitting bacterial infection of the urinary tract. Twenty-one new derivatives of N-aliphatic-acylglycinohydroxamic acids (GHAs) were synthesized, and their inhibitory potencies against the urease activity of sword bean in a phosphate buffer and against the ureolytic activity of Proteus mirabilis in human urine, and their urinary excretion rates in rats were also measured for this purpose I50 values of most of GHAs against the urease activity of sword bean were about 1 to 10 microM and 2-ethyl-n-butyroyl GHA was the most potent inhibitor with the value of 0.79 microM. I50 values of most of the GHAs against the ureolytic activity of Proteus mirabilis were about 5 to 50 microM and n-nonaroyl GHA was the most potent inhibitor with the value of 3.6 microM. 2,2-Dimethylpropionyl GHA had the highest urinary excretion rate with the recovery of 11%. Routes of administration of 2,2-dimethylpropionyl GHA and sex of rats used did not affect the amount of urinary excretion at all. The results in this report suggest that DL 2-methyl-n-butyroyl, 2-ethyl-n-butyroyl and 2,2-dimethylpropionyl GHA are the most hopeful therapeutic agents for urolithiasis among them.

Animals↗
PubMed2006

Novel determination system for urea in alcoholic beverages by using an FIA system with an acid urease column.

A novel determination method for urea using an acid urease column-FIA system was developed, and the system was applied to the determination of urea in rice wine. This novel FIA system was characterized by CO2 detection due to the property of acid urease and by a microfluidic gas-diffusion device with the use of an ultra-thin hollow fiber membrane. A biosensing system fabricated in this study was assembled with a double-plunger pump, a sample-injection valve, an immobilized acid urease column as a recognition element for the assay of urea, a gas-diffusion unit, and a flow-type spectrophotometer. The gas-diffusion unit consisted of a double-tubing structure in which the outer tubing was made of PTFE (i.d. 1.0 mm; o.d. 1.5 mm) and the inner tubing was of porous PTFE (i.d. 0.19 mm; o.d. 0.25 mm). Standard urea solutions (20 microl) were measured through monitoring variations in the absorbance of a coloring agent solution resulting from a pH shift due to carbon dioxide molecules being enzymatically generated. A wide and linear relationship was obtained between the concentration of urea (16 microM - 1.0 mM) and the change in absorbance. This FIA system has great advantages that the system did not suffer from ammonia and ethanol in samples. This system, armed with a microfluidic gas-diffusion device, was applicable to the determination of various substrates of many kinds of decarboxylase, amino-acid oxidase, and amino-acid oxygenase, producing CO2 and NH3 molecules.

Acids↗
PubMed1989

The reliability of urease tests, histology and culture in the diagnosis of Campylobacter pylori infection.

The accuracy of various staining techniques for immersion microscopy, of five media for culture and five urease test modalities for the detection of Campylobacter pylori infection is reported. It was found that 2% urea unbuffered gel preparation is the most accurate urease test (sensitivity: 89%, specificity: 98%) but a minimal amount of 10,000 CFU/ml is necessary to observe positivity and the sensitivity of urease tests drops to 52% in patients under antimicrobial treatment. For histological diagnosis, modified Giemsa staining was shown to be slightly superior to H&E. The most valuable diagnosis technique is culture when the biopsy specimen is transported and processed under appropriate conditions. A 94% sensitivity rate was observed with 'BCC agar', a new medium containing brain heart infusion, activated charcoal and horse serum.

Bacteriological Techniques↗
PubMed1993

An in vitro study of enhanced H+ diffusion by urease action on urea. Implications for Helicobacter pylori-associated peptic ulceration.

The in vitro effect of urea and hydrolysis of urea by urease on mucus H+ permeability is reported here. The effective DHCl values indicate a strong pH dependence for H+ diffusion in both water and mucus layers, with no apparent trend at concentrations between 1 and 50 mM urea. However, the estimated DHCl at near-neutral and alkaline pH are 4- to 10-fold lower through mucus than through aqueous films. Moreover, the pKa values of HCO3- and NH3 (generated by urease action on urea) had a profound effect on measured DHCl. These in vitro studies suggest that a high local concentration of NH3 and HCO3- within the mucus layer, generated by the action of Helicobacter pylori urease on endogenous intragastric urea, could greatly accelerate proton flux to the surface epithelium by operation of a buffer shuttle. This results in enhanced H+ permeability, particularly at pKa values of HCO3- and NH3, and in extreme circumstances it may result in gastric ulcer formation.

Animals↗
PubMed2004

Selection and properties of Streptococcus thermophilus mutants deficient in urease.

Natural variations of the urea content of milk have a detrimental effect on the regularity of acidification by Streptococcus thermophilus strains used in dairy processes. The aim of the present study was to select urease-deficient mutants of S. thermophilus and to investigate their properties. Using an improved screening medium on agar plates, mutants were selected from 4 different parent strains after mutagen treatment and by spontaneous mutation. Most mutants were stable and had a phage sensitivity profile similar to that of their parent strain. Some of them contained detrimental secondary mutations, as their acidifying activity was lower than that of the parent strain cultivated in the presence of the urease inhibitor flurofamide. The proportion of this type of mutant was much lower among spontaneous mutants than among mutants selected after mutagen treatment. Utilization of urease-deficient mutants in dairy processes may have several advantages, such as an increase in acidification, an improved regularity of acidification, and a lower production of ammonia in whey.

Base Sequence↗
PubMed2002

Cutting edge: urease release by Helicobacter pylori stimulates macrophage inducible nitric oxide synthase.

Inducible NO synthase (iNOS) expression and production of NO are both up-regulated with Helicobacter pylori infection in vivo and in vitro. We determined whether major pathogenicity proteins released by H. pylori activate iNOS by coculturing macrophages with wild-type or mutant strains deficient in VacA, CagA, picB product, or urease (ureA(-)). When filters were used to separate H. pylori from macrophages, there was a selective and significant decrease in stimulated iNOS mRNA, protein, and NO(2)(-) production with the ureA(-) strain compared with wild-type and other mutants. Similarly, macrophage NO(2)(-) generation was increased by H. pylori protein water extracts of all strains except ureA(-). Recombinant urease stimulated significant increases in macrophage iNOS expression and NO(2)(-) production. Taken together, these findings indicate a new role for the essential H. pylori survival factor, urease, implicating it in NO-dependent mucosal damage and carcinogenesis.

Animals↗
PubMed1988

The ELISA-U: an enzyme-linked immunosorbent assay using urease as the enzyme marker for rapid detection of Plasmodium falciparum antibody in human serum.

A visual, enzyme-linked immunosorbent assay using urease (ELISA-U) as the enzyme marker was adapted for rapid detection of antibody against Plasmodium falciparum. Flat-bottom, 96-well microtiter plates were coated with P. falciparum soluble antigen obtained by saponin and NP-40 treatment of parasite cultures. Antibody was detected by successive incubations with test sera, urease-conjugated rabbit-human antibody, and urease substrate. Reactive sera developed a definite and easily visualized purple color. Sera from patients with single infections of P. vivax or P. ovale were unreactive. No cross-reactivity was noted with sera from patients with rheumatoid arthritis, filariasis, amebiasis, schistosomiasis, dengue, scrub typhus, leptospirosis, or toxoplasmosis. The procedure can be performed at room temperature and completed within 1 hr. The sensitivity of the assay is comparable to that of the indirect fluorescent antibody test at all but the lowest dilutions tested.

Animals↗
PubMed1975

Benurestat, a urease inhibitor for the therapy of infected ureolysis.

A single oral administration of the urease inhibitor benurestat (2-(p-chlorobenz-amido)acetohydroxamic acid) to the human at 15 or 25 mg per kg produced, for 4 hr, mean urinary levels of inhibitory activity that were 700 to 1900 times that equivalent concentration of benurestat required to inhibit Proteus mirabilis urease by 90 per cent. In the rat these same dosage levels produced urinary inhibitory activity equivalent to 16 to 140 fold that required for 90 per cent urease inhibition. Benurestat administration, 25, 50, or 100 mg per kg, caused a decrease in the urinary excretion of ammonia from rats with experimental P. mirabilis genitourinary tract infection. The formation of struvite calculi was inhibited under these conditions. Nitrofurantoin, sulfamethoxazole, and ampicillin also slowed the formation of struvite calculi in infected rats and together with benurestat a potentiation of the inhibition of calculi formation was secured. Some combination therapies composed of benurestat plus an antibacterial agent, sulfamethoxazole or ampicillin, were effective in promoting the net dissolution of formed calculi. The number of viable bacteria present in the bladders of infected rats was significantly less after the administration of benurestat plus nitrofurantoin, sulfamethoxazole, or ampicillin than the respective numbers that were obtained from control infected rats or from rats administered either component of the combination separately.

Ammonia↗
PubMedDate not supplied

[Urease inhibition by polymer analogs of substrate and thiophosphamides].

Inhibition of soybean urease by polymeric substrate analogues, urea and thiourea polydisulfides (PDSU and PDSTU, respectively), or three thiophosphoric acid amides (TPAA), tri-(N-3-hydroxyphenyl)thiophosphamide (1), tri-(N-4,4'-aminodiphenyl)thiophosphamide, and di-oxy-(N-alpha-piridyl)thiophosphamide (3) was studied in aqueous solutions at various pH values. The inhibitory effects of all these substances were reversible and competitive with the lowest inhibition constant Ki 2.8 microM for TPAA-1 at pH 3.85. Above and below this pH value, Ki increased reaching 24 [mu]M at pH 7.2. All test substances inhibited urease comparably with known inhibitors such as thiols (cysteamine, etc.) and hydroxamic acid derivatives, but were less efficient than phosphorodiamidates. Structural features of possible urease inhibitors of higher efficiency were proposed.

Enzyme Inhibitors↗
PubMed1976

Four commercial urease reagents and a laboratory-prepared reagent compared for analysis of blood urea nitrogen with the Beckman analyzer.

Three laboratory-prepared urease reagents were compared with a commercial preparation supplied for routine use on the Beckman Blood Urea Nitrogen Analyzer. There were discrepancies in results for urea nitrogen among the four urease reagents when matching serum and the corresponding oxalate/fluoride treated plasma were compared as measured with the Beckman Analyzer and continuous-flow (AutoAnalyzer) method. All four urease preparations were affected by fluoride, but to different extents. We believe that an effective laboratory reagent can be prepared in the laboratory at significantly lower cost.

Autoanalysis↗
PubMed1992

[Role of bacterial metabolism in transformation of non-mutagenic compounds into mutagens. II. Participation of bacteria producing urease in degradation of pesticides--urea derivatives].

Participation of bacteria producing urease: Proteus mirabilis and Staphylococcus epidermidis in degradation of pesticides--urea derivatives, was investigated. Four new compounds were studies: N-/(3-trifluoromethyl)phenyl/N'-(2-cyanoethyl)-urea (IPO 6584), N-(4-chlorophenyl)-N'-(2-hydroxyethyl)-N'-ethylurea (PO 6236), N-(4-chlorophenyl)-N'-(2-hydroxyethyl), N'-propyl-urea (IPO 6237), N-(2-hydroxyethyl), N-methyl-N'-(3,4 dichlorophenyl)-urea (IPO 3102), pesticide reference standard--thiram fungicide--tetramethyl-bis-thiocarbamyl disulfide, and rodenticide-alpha-naphthylthiourea (ANTU). Investigated compounds were incubated with cells of P. mirabilis 4508 ans S. epidermidis CCM 2448 and commercial preparation of urease from beans. Mutagenicity of resulting metabolites was then studies by the Ames test. All compounds were decomposed by bacteria used in this study, as well with beans urease with different activity. Reaction products did not exhibit mutagenic activity for test strains S. typhimurium his- TA97a, TA98, TA100 and TA102.

Biotransformation↗
PubMed2003

[Effect of atrazine on urease activity in soils with different fertility].

Four soils with different fertility were treated with different concentrations of atrazine. The results showed that the urease activity was stimulated in the soils treated with low concentration of atrazine at the first day, while inhibited after treated with high concentration of atrazine during the whole period of the experiment. There was a significant difference in urease activity in soils with different fertility after treated with high concentration atrazine. The urease activity in CK and in NPK was significantly inhibited, the inhibition rate reached 30.35% and 28.89%, respectively, but in NPK + S and NPK + M, the inhibition rate was only 21.35% and 16.86%, respectively. The maximum inhibition rate appeared later in soils with high than with low fertility, showing that soils with high fertility could endure the effect of atrazine.

Atrazine↗
PubMed2004

[Influence of urease activity of the oral cavity and oropharynx on 13C-urea breath test].

We examined whether 13C-urea breath test with powdered 13C-Urea is affected with urease activity in the oral cavity and oropharynx in H. pylori negative cases. We also examined whether the degree of gargling affects the results of 13C-UBT. The results demonstrated that the urease activity not only in the oral cavity, but in the oropharynx may influence the UBT value. Therefore, it is possible that the UBT value may be affected with relic urease activity in the oropharynx if only the oral cavity is gargled. In conclusion, Gargling of the oropharynx in addition to the oral cavity is important to obtain true negative diagnosis with 13C-UBT in patients without Helicobacter pylori infection.

Adult↗
PubMedDate not supplied

[Inhibition of soybean urease by polycarbonyl compounds].

Competitive inhibition of soybean urease was studied at 36 degrees C in aqueous solution (pH 4.95) in the presence of polycarbonyl compounds (PCCs): oxalyldihydrazide (ODH), its polydisulfide (poly(DSODH)), three cyclic beta-triketones (CTKs), and seven cyclic PCC species of differing structure. The inhibition constants of ureolysis (Ki) varied in the range 8.5-3800 microM depending on the structure of organic chelators for the nickel atom in urease. It was shown that pH variation within the range from 3.85 to 7.40 exerted a strong effect on the values of Ki] of three CTKs and hydroxyurea, which was used as a reference: pH dependences of lgK(i) were linear in all cases and displayed a break at pH 6.0-6.5. The most effective inhibitor of ureolysis was poly(DSODH), which contained approximately 28 carbonyl groups in the polymer molecule. The role of such factors as the number of carbonyl groups per PCC molecule, mutual arrangement, and reaction medium pH in the efficiency of the process of urease inhibition is discussed.

Catalysis↗
PubMed2005

[Detection of Helicobacter pylori in nasal polyps specimens using urease test GUT plus].

In patients with nasal polyps the colonisation of nasal polyps tissues by Helicobacter pylori was investigated using urease test (GUT plus). In this prospective clinical trials we enrolled 61 subjects who had undergone endoscopic nasal polyps surgery and 30 subjects who had undergone septoplasty (control group) were questioned and biopsy specimens of the removed polyps or the mucosal part of inferior turbinate were tested by the urease test GUT plus. In result Helicobacter pylori was not found in the nasal polyps and mucosal part of inferior turbinate tissue of any of patients including the 43 of 61 patients with nasal polyps and 7 of 30 patients with septum deviation who had symptoms of gastroesophageal reflux. In our study using the urease test GUT plus we were not able to confirm presence of Helicobacter pylori in the nasal polyps tissue. However, further epidemiologic studies using different diagnostic methods would be necessary to confirm presence of Helicobacter pylori as potential underlying pathogenetic mechanism of nasal polyposis.

Adult↗
PubMed2006

[Super catalytic antibodies (antigenase) capable of destroying H. pylori urease].

Antigenase has an ability to decompose the antigen peptide or protein. We have produced some monoclonal antibodies(HpU mAbs series) for H. pylori urease. Out of them, the light chain of HpU-9 mAb possesses a catalytic triad composed of Asp, Ser and His, which acts as a catalytic site against the antigen, based on the structural analysis of molecular modeling. HpU-9-L belongs to the germline cs1 which inherently encodes the catalytic triads in the sequence, indicating that HpU-9-L must be an antigenase. As expected, HpU-9-L showed the specific degradation against the beta-subunit of the urease. The heavy chain of HpU-2 also exhibited the specific degradation of the urease. These antigenases will be used for the medicinal application.

Antibodies, Monoclonal↗