Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:6.3.4.6 (urease)
7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A low ventilation model to induce ascites was introduced and characterized. In addition, the effect of supplemental air mixing via ceiling fans (CF) and the feeding of a urease inhibitor (0, 125, and 250 ppm) on incidence of ascites were investigated. Twelve environmental chambers were utilized in the trial; six were fitted with CF. Each dietary treatment was replicated twice per CF treatment. One hundred and twenty day-old male commercial broilers were reared per chamber. Atmospheric O2, CO2, and NH3, temperature, and humidity, as well as weekly litter moisture and pH, were monitored. Chamber CO2 levels increased immediately then stabilized. Chamber NH3 levels increased between 2 to 4 wk of age and rapidly declined when ventilation rates were increased to 1 cfm per bird. The CF and dietary treatments had little effect on air or litter variables except for NH3. Supplementing the diet with urease inhibitor resulted in a greater than 50% reduction in cumulative mortality due to ascites and a slight reduction in weekly BW gains. The CF treatment had no effect on production variables such as weekly feed intake, gain, and feed to gain ratio, or survivability due to ascites.
...
PMID:Effect of a urease inhibitor and ceiling fans on ascites in broilers. 1. Environmental variability and incidence of ascites. 807 22

Texel wethers (68 +/- 2.5 kg BW) fitted with catheters in the ruminal veins and a mesenteric artery, blood flow probes on ruminal arteries, and a ruminal cannula were fed 500 g of orchardgrass hay every 12 h. During the last third of the feeding cycle, intraruminal injections were performed to evaluate the effect of urease activity, osmolality, and concentrations of NH3, butyrate, and CO2 in the rumen on urea and NH3 fluxes across the rumen wall. At pH 6.7, NH3 absorption increased with NH3 and butyrate concentrations in the rumen, and to a lesser extent with CO2 concentration. The increase in ruminal blood flow associated with CO2 and butyrate increase was always greater than the increase in NH3 absorption. Increasing ruminal osmolality slightly decreased NH3 absorption. Ruminal NH3 concentration and ruminal blood flow seemed to be the main determinant of NH3 absorption. Decreasing urease activity in the rumen decreased urea net transfer. The net transfer of urea to the rumen was stimulated by CO2. High concentrations of NH3 (330 mg of N/L) and butyrate (25 mM) in the rumen decreased urea net uptake, whereas osmolality (up to 420 mOsmol/L) did not affect it. Modifications in ruminal blood flow or water net movement across the ruminal wall did not seem to account for the effect of CO2, NH3, and butyrate on urea net uptake.
...
PMID:Net transfer of urea and ammonia across the ruminal wall of sheep. 822 81

Urease in the human gastric mucosa is a marker for infection with Helicobacter pylori (HP), an organism which is associated with peptic ulcer disease. To detect gastric urease, we examined 184 patients (144 males, 40 females; mean age: 49.8 +/- 15.6 years) with suspected peptic ulcer disease. Fasting patients were given orally 5 microCi of carbon-14 labelled urea. From each patient only one breath sample was collected in hyamine at 10 min. The amount of 14C collected at 10 min was expressed as follows: [(DPM/mmol CO2 collected)/(DPM administered)] x 100 x body weight (kg). The presence of HP colonization was determined by examination of multiple endoscopic prepyloric antral biopsy specimens subjected to culture or a rapid urease test. For the purpose of this study, HP-positive patients were defined as those with characteristic bacteria as indicated by a positive result of either the culture or the rapid urease test; HP-negative patients were defined as those with negative findings on both the culture and the rapid urease test. Of the 184 cases, 99 (53.8%) were positive for HP infection, and 85 (46.2%), negative. The sensitivity and specificity of the rapid 10 min 14C-urea breath test for the diagnosis of HP-associated peptic ulcer disease were evaluated by a receiver operating characteristic (ROC) curve with a variable cut-off value from 1.5 to 4.5. When a cut-off value of 1.5 was selected, the sensitivity was 100% and the specificity, 83.5%; when a cut-off value of 4.5 was selected, the sensitivity was 54.5% and the specificity, 97.6%.
...
PMID:Accuracy of a rapid 10-minute carbon-14 urea breath test for the diagnosis of Helicobacter pylori-associated peptic ulcer disease. 840 59

Proteus mirabilis, a significant cause of bacteriuria and acute pyelonephritis in humans, produces urease. This high-molecular-weight, multimeric, cytoplasmic enzyme hydrolyzes urea to ammonia and carbon dioxide. To assess the role of urease in colonization, urolithiasis, and acute pyelonephritis in an animal model of ascending urinary tract infection, we compared a uropathogenic strain of P. mirabilis with its isogenic urease-negative mutant, containing an insertion mutation within ureC, the gene encoding the large subunit of the enzyme. Mice challenged transurethrally with the parent strain developed significant bacteriuria and urinary stones. The urease-negative mutant had a 50% infective dose of 2.7 x 10(9) CFU, a value more than 1,000-fold greater than that of the parent strain (2.2 x 10(6) CFU). The urease-positive parent strain reached significantly higher concentrations and persisted significantly longer in the bladder and kidney than did the mutant. Indeed, in the kidney, the parent strain increased in concentration while the mutant concentration fell so that, by 1 week, the parent strain concentration was 10(6) times that of the mutant. Similarly, the urease-positive parent produced significantly more severe renal pathology than the mutant. The initial abnormalities were in and around the pelvis and consisted of acute inflammation and epithelial necrosis. By 1 week, pyelitis was more severe, crystals were seen in the pelvis, and acute pyelonephritis, with acute interstitial inflammation, tubular epithelial cell necrosis, and in some cases abscesses, had developed. By 2 weeks, more animals had renal abscesses and radial bands of fibrosis. We conclude that the urease of P. mirabilis is a critical virulence determinant for colonization, urolithiasis, and severe acute pyelonephritis.
...
PMID:Contribution of Proteus mirabilis urease to persistence, urolithiasis, and acute pyelonephritis in a mouse model of ascending urinary tract infection. 851 76

Urease (EC 3.5.1.5) catalyses the hydrolysis of urea to ammonia and carbon dioxide. The enzyme from Sporobolomyces roseus was enriched 780-fold and purified to apparent homogeneity using heat treatment, ion exchange chromatography on Q-Sepharose fast flow, hydrophobic interaction chromatography on Phenyl-Sepharose, size exclusion chromatography on Sephacryl S 300 HR, and ion exchange chromatography on MonoQ. Analysis of the purified enzyme by SDS-PAGE demonstrated the presence of subunits with a molecular weight of 90 (+/- 4) kDa. The M(r) of the native enzyme was estimated by size exclusion chromatography to be 340 (+/- 30) kDa, suggesting a tetrameric structure different from other ureases isolated so far from both prokaryotes and eukaryotes. The enzyme was heat-stable, showing no loss of activity after incubation at 70 degrees C for 15 min. The highest urease activities were observed after growth on media containing urea as the sole source of nitrogen.
...
PMID:Purification and properties of urease from Sporobolomyces roseus. 857 78

Klebsiella aerogenes urease in a Ni-containing enzyme (two Ni per alpha beta gamma unit) that is purified as an apoprotein from cells grown in Ni-free medium. Partial activation of urease and UreD-urease apoproteins is achieved in vitro by incubation in the presence of Ni(II) and CO2, whereas incubation of these proteins with Ni alone leads to the formation of inactive species [Park, I.-S., & Hausinger, R. P. (1995) Science 267, 1156-1158]. Here we determined the kinetics of these inhibitory reactions and demonstrated the presence of two Ni ions per alpha beta gamma unit in the inactive proteins. Although metal-substituted urease has never been purified from Ni-deprived cell, several other metal ions were shown to bind to the urease apoproteins. Divalent Zn, C, Co, and Mn all inhibited Ni- and Co2-promoted urease activation at concentrations below that of Ni, whereas Mg and Ca ions did not inhibit this process. Ni-inhibited species recovered their ability to be partially activated after EDTA treatment. In contrast, samples that were exposed to Co or Cu ions were irreversibly inactivated, and EDTA treatment of Zn- or Mn-inhibited samples led to reduced levels of activation competence. Mn-substituted urease, generated from urease apoprotein samples in a Mn- and Co2-dependent manner, was shown to be active, whereas other metal-substituted forms if urease lacked activity. The Mn-protein possessed only 2% of the activity of Ni-activated apoprotein [ approximately 8.0 vs approximately 400 mumol min-1 (mg protein)-1], but its KM value was only moderately altered from that of the native enzyme (3.86 +/- 0.15 mM vs 0.2 mM). Unlike the Ni-containing enzyme, Mn-urease was inhibited by EDTA. Given the evidence that urease apoprotein binds numerous metal ions, we speculate on possible roles for the UreD, UreF, and UreG accessory proteins in urease activation.
...
PMID:Metal ion interaction with urease and UreD-urease apoproteins. 861 23

Helicobacter pylori has been implicated as an agent in the pathogenesis of antral gastritis, gastric and duodenal ulcer and probably in gastric cancer. The C13 urea breath test is a diagnostic method quick to perform, sensitive, reliable and non invasive. It is based on the presence of Helicobacter pylori urease activity, which permits to detect it in the infected mucosa. A substrate (urea) labelled with Carbon 13 is administered to the patient and exhaled breath is collected to detect the possible catabolism product (CO2 labelled with C13). In the European protocol, patients in fasting condition are given a test meal to delay gastric emptying and five minutes later a solution which contents 100 mg of C13 labelled urea. Breath samples are collected before and 30 minutes after urea was given. In our first year of experience, 363 patients with Helicobacter pylori infection detected by histology or urease were studied by C13 urea breath test, with a sensitivity and specificity of 95 and 96%. False negatives may occur if the test is used after antibiotics and other antiulcer drugs. Its main indication is to monitor eradication therapy after treatment. Its possible use as a quantitative test still remains unclear.
...
PMID:[C13 urea breath test in the diagnosis of Helicobacter pylori infection in the gastric mucosa. Validation of the method]. 864 14

The current AOAC method (963.28) for large-scale (50 g) testing of urine on grain is based on the reaction of sodium in urine with magnesium uranyl acetate. Detection of sodium suggests that urine is present and that a test for urea is appropriate. Urea is detected with urease-bromothymol blue-paper and is confirmed through its reaction with xanthydrol to form dixanthylurea crystals, which are detected microscopically. The initial nonspecific test for sodium can be influenced by the presence of salt or other sodium compounds. Furthermore, the magnesium uranyl acetate spray used in Method 963.28 potentially exposes the analyst to the aerosol of a volatile, toxic uranium compound. Excess reagents and analyzed test portions must be disposed of as radioactive waste. In addition, Method 963.28 requires several steps to determine the presence of urea. The alternative AOAC method (972.41) tests for the presence of urea from urine on individual seeds. Urea is enzymatically decomposed to ammonia and carbon dioxide by urease. Liberated ammonia shifts the pH, changing the color of the indicator in the agar from yellow to blue. This study adapts Method 972.41 to larger test samples. Up to 25 g grains and seeds are sprayed with urease test agar instead of being individually immersed in the urease test agar. The modified method was used to analyze urea on seeds and grains of 24 plants from 4 families. The method has a limit of detection of one seed contaminated with 1 microgram urea.
...
PMID:Use of urease-bromothymol blue-agar method for large-scale testing of urine on grain and seeds. 875 45

Sixty-three breath samples were collected from patients who underwent a 14C-urea breath test. Following ingestion of a radiolabelled 14C-labelled urea solution, breath samples containing 14C-labelled carbon dioxide were trapped in a solution containing hyamine hydroxide. Samples were then counted in a liquid scintillation counter. Breath samples were collected at 2, 15, 20, 25 and 30 minutes following ingestion of the urea solution. The presence or absence of Helicobacter pylori (HP) infection was determined on the basis of endoscopic biopsy tests which included culture, histological examination, rapid urease test and a gram stain of a fresh tissue smear. Thirty-two HP positive and 31 HP negative samples were collected. The mean counts at 15, 20, 12 and 30 minutes time points were: 4413, 4458, 4109 and 3795 dpm respectively for the positive samples and 1275, 877, 690 and 565 dpm respectively for the negative samples. Based on a cutoff value (mean of the negative samples + 3 standard deviations) for every time point, HP positive and negative samples could be clearly differentiated giving a sensitivity and specificity of 100%. The 14C-urea breath test is a reliable and convenient diagnostic test for H. pylori.
...
PMID:14C-urea breath test: a useful non-invasive test in the diagnosis of Helicobacter pylori infection. 892 96

We have devised a procedure that permits the cultivation of a gram-positive coccoid species from biopsy material obtained from the antrum of the stomachs of patients with gastric disorders. Antibodies directed against surface proteins obtained from the coccoid isolates were detected in all patients with gastric disorders examined in this study, including both Helicobacter pylori-infected and H. pylori-uninfected patients. Several of these isolates, including a prototype designated strain SL100, have been characterized in some detail. Strain SL100 exhibits urease and exceptionally high catalase activities and assumes a variety of spherical morphologies as detected by electron microscopy. This isolate expresses an adhesin that binds to gastric mucin. The adhesin activity was detected only after the isolate was exposed to an acidic pH, suggesting that in the natural process of infection, the low pH of the stomach unmasks a cell surface component with adhesin activity. Strain SL100 grows best under a microaerophilic conditions (10% CO2, 5% O2, 85% N2), but it also grows quite well under aerobic conditions. Thus, this organism would be expected to proliferate outside of the human host as well as in the gastric mucosa. Oral infection of newborn piglets resulted in colonization of the gastric antrum and growth retardation. Preliminary taxonomic classification indicates similarity to the Staphylococcus DNA homology groups containing S. cohnii and S. xylosus. One of us (C.K.) apparently became infected with this organism as indicated by gastric symptoms and the subsequent presence of strain-specific antisera not present in other workers in the laboratory.
...
PMID:Successful cultivation of a potentially pathogenic coccoid organism with trophism for gastric mucin. 897 91


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---