Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We used a differential thermal detector in conjunction with an immobilized urease reactor to determine urea in serum. Samples (120 mul) are introduced into a flow stream and passed through an "adiabatic" column, which is packed with enough insolubilized urease to completely convert urea to ammonia and carbon dioxide. Measured temperature changes are directly proportional to the serum urea concentration. Urea in the presence of protein, bilirubin, and hemoglobin can thus be rapidly, simply, and inexpensively measured. Results correlate well with those obtained by the manual diacetyl monoxime and urease/indophenol methods.
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PMID:Rapid-flow enthalpimetric determination of urea in serum, with use of an immobilized urease reactor. 94 41

Approximately 10% of the members of the Koya Dora tribe from Andhra Pradesh (India) carry an alpha chain hemoglobin variant, Hb Koya Dora (Hb KD), usually in amounts of 0.5%-2% of total hemoglobin. In four presumed homozygotes for Hb KD, up to 10% of the abnormal hemoglobin was present. The alpha chain of Hb KD was found to be elongated by at least 16 residues, possibly as a result of a mutation of the normal alpha chain termination codon UAA TO UCA, coding for serine. A pedigree in which two individuals possess Hb KD as well as the alpha chain variant Hb Rampa and normal Hb A proves the existence of two alpha chain loci in this population. Hb DK resembles the previously described Hb Constant Spring [6, 7] in many aspects, probably also in its alpha thalassemia-like expression.
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PMID:Hemoglobin Koya Dora: high frequency of a chain termination mutant. 115 53

A 91.5% mass yield of urease and hemoglobin (Hb), co-encapsulated within polyamide membranes, was determined spectrophotometrically. The specific activity yield of microencapsulation was 84%, twofold higher than values previously reported, as a result of optimization of encapsulation conditions. The kinetic parameters and pH activity profiles of intracapsular urease were determined to be similar to those corresponding to the free enzyme. Similar activities were also observed for intact and microcapsule homogenate, indicating minimal mass transfer and diffusional limitation. The active configuration of the enzyme appears to remain intact upon microencapsulation. The application of a kinetic model for encapsulated urease further indicated that the kinetics were reaction-controlled with minimal mass transfer restrictions.
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PMID:Kinetics and activity distribution of urease coencapsulated with hemoglobin within polyamide membranes. 141 44

Cytochrome c, hemoglobin, urease and liver microsomes were microencapsulated in aqueous solution by use of a new method. The membrane of the microcapsules consist of a symplex, which is formed predominantly by electrostatic interactions between a polymeric polyanion and a polymeric polycation. The membrane is characterized by high mechanical stability and is a barrier for globular substances with molecular weights larger than 12000, but permeable for substances with lower molecular weight. The microcapsules contain the protein or microsomes and additionally the polymeric polyanion in the liquid interior. Structure and function of microencapsulated proteins and microsomes are preserved. The developed method of microencapsulation opens new possibilities for the application of biomacromolecules, particularly for extracorporal detoxification.
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PMID:[Immobilization of proteins and cell fragments using a new method of microencapsulation]. 631 45

The antioxidant activity of skim milk was evaluated in a linoleate emulsion system with hemoglobin as a pro-oxidant. Sonication greatly increased the antioxidant activity of skim milk. The antioxidant activity of the casein fraction of milk was increased most by sonication, and this increase was nearly as great as that for skim milk, suggesting that casein was almost totally responsible for the antioxidant effect of sonication. Total sulfhydryl groups of skim milk decreased upon prolonged sonication, probably the result of the heat evolved in the process. Reactive sulfhydryl content was unchanged by sonication. Sonication had no effect on antioxidant activity of beta-lactoglobulin, reduced urease, or reduced ribonuclease, proteins with free sulfhydryl groups. Apparently sulfhydryl groups were not involved in the increased antioxidant activity of sonicated skim milk. Homogenization at 281.5 kg/cm2 did not increase the antioxidant effect of skim milk. Sonication probably disrupted casein micelles, increasing the effective concentration of casein, which could account for the increased antioxidant activity in the system.
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PMID:Antioxidant activity of skim milk: effect of sonication. 689 12

We followed the "abbreviated precision protocol" of the National Committee for Clinical Laboratory Standards for the evaluation of precision, accuracy, and carryover in analysis for urea nitrogen with the multilayer film analysis system ("Ektachem"). We analyzed 456 clinical samples with this instrument, by the manual urease/glucose dehydrogenase method, and with the Beckman System I GLU/BUN Analyzer. Precision and accuracy were estimated for 50, 220, 270, and 500 mg/L urea nitrogen concentrations in 100, 30, or 20 microL of serum. Potential interference of 15 compounds was evaluated. Random error (defined as 1.965 X SD) was 7, 10, 12, and 18 mg/L. Systematic error was 3, 4, 5, and 15 mg/L. Total analytical error was 11, 14, 17, and 34 mg/L for analysis of 100 microL of serum at the above-stated urea nitrogen concentrations. The greatest interference (6 mg/L) was caused by ethanol (300 mg/L) and by hemoglobin (500 mg/L) in the urea nitrogen (at 260 mg/L) determination. Urea nitrogen concentration, as determined with the Ektachem was linearly related to the expected concentration, at least up to 1187 mg/L. Carryover was not statistically significant.
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PMID:Extended clinical trial and evaluation of urea nitrogen determination with the Ektachem GLU/BUN analyzer. 700 69

We describe a coupled-enzyme equilibrium method for measuring urea in serum, which is performed on supernates prepared by treating each specimen with Ba(OH)2 and ZnSO4 (Somogyi reagent). Analytical recovery of [14C]urea added to a variety of matrices was essentially complete (mean, 100.6%) for the supernates after precipitation. Nine variables were univariately examined in arriving at the reaction conditions for the method: glutamate dehydrogenase, urease, 2-oxoglutarate, ADP, Tris . HCI, NADH, EDTA, pH, and temperature. The reagent is stable for at least 48 days at--20 degrees C and for 23 days at 4 degrees C. Mean analytical recovery of urea (14 mmol/L) added to seven different specimens (three different matrices) was 100.8%. The analytical linear range of the method extends to 30 mmol of urea per liter. Of 22 potential interferents, only bilirubin at 1 mmol/L (580 mg/L), hemoglobin at 10 g/L, and hydroxyurea at 6 mmol/L showed more than 2% interference. We discuss precision and effects of specimen dilution, and compare results for 100 human serum specimens with those measured for the same specimens with four other urea methods. We examined the effects of measuring a blank, consisting of sample and reagent without urease, with each specimen.
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PMID:A coupled-enzyme equilibrium method for measuring urea in serum: optimization and evaluation of the AACC study group on urea candidate reference method. 737 2

Results presented in the companion paper suggested that the protein itself might be actively involved in the polymerization process while being entrapped in polysiloxane polymers. It was speculated that the organo-functional side chains on the silanol monomers (or small oligomers) tended to associate with complementary residues on the protein surface during the polymerization process. This phenomenon might lead to complementary binding pockets for the protein on the polymer. To investigate this possibility, polysiloxane polymers were prepared from 3-aminopropyltriethoxysilane and tetraethylorthosilicate (1:3) in the presence of two proteins: urease and BSA. The entrapped proteins were removed by pronase digestion and washing and the resulting polymers evaluated for their ability to again bind the two proteins. It was found that urease preferentially bound to the polymer made in the presence of urease, and BSA preferentially bound to the polymer made in the presence of BSA. The absolute preferential binding excess was greater (30%) for urease binding relative to that observed for BSA (3%). However, in both cases the same relative binding ratio of 1.5 or 50% excess was found. A similar study using the closely related hemoglobin and myoglobin proteins failed to show comparable excess binding in the presence of the predetermined protein. In the latter case, it was demonstrated that the rebound proteins did not equilibrate with labeled solution proteins, indicating a very tight association with the polymer surface possibly masking any specificity which existed. However, it was possible to show that urea release of rebound hemoglobin from the polymer made in the presence of hemoglobin was less than for myoglobin bound to the same polymer and visa versa, again suggesting induced properties unique to the polymer prepared with the predetermined protein. To the extent that this notion of induced complementary order is correct, it may have implications in the development of protein specific adsorbants and in our understanding of polymer surface adhesion and the molding of template fine structure.
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PMID:Influence of protein on polysiloxane polymer formation: evidence for induction of complementary protein-polymer interactions. 763 16

To evaluate whether eradication with omeprazole and amoxicillin results in a reduction of ulcer recurrence and rebleeding in patients with Helicobacter pylori-associated duodenal ulcer hemorrhage, patients with upper gastrointestinal hemorrhage from duodenal ulcers with stigmata of recent hemorrhage, a drop in hemoglobin level of more than 2 g/dL, and documented H. pylori infection (by rapid urease test and histologic findings) were randomly assigned to receive omeprazole, 40 mg every day, and amoxicillin, 1 g twice a day, (Group A) or omeprazole alone, 40 mg every day, (Group B) for 2 weeks. No maintenance antiulcer therapy was given. Patients underwent a second endoscopy 4 weeks after completion of therapy and were followed for 1 year. Endoscopy was performed again at the end of 1 year. All patients showed ulcer healing 4 weeks after completion of therapy. H. pylori eradication rates were 83% (Group A) and 5% (Group B) (p < .001). Ulcer recurrences were significantly lower in Group A (3/29 or 10%) than in Group B (9/22 or 41%; p < .05). Comparison of Group A patients with eradication and Group B patients without eradication also revealed a significant difference in rates of ulcer relapse (1/24 or 4% versus 9/21 or 43%; p < .01). Rebleeding occurred significantly less often in the dual therapy group than in the omeprazole group (0/29 versus 6/22 or 27%; p < .01). Eradication of H. pylori significantly reduces the rates of ulcer recurrence and rebleeding in patients with duodenal ulcer bleeding. Dual therapy with omeprazole and amoxicillin should be considered in all H. pylori-positive patients with hemorrhage from duodenal ulcers.
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PMID:Helicobacter pylori eradication reduces the rate of rebleeding in ulcer hemorrhage. 863 23

Restricted ventilation was used to experimentally induce ascites in commercial male broilers. The role of a dietary urease inhibitor (0, 125, and 250 ppm) and ceiling fans to reduce ascites was investigated. At 6 wk of age, birds were bled, euthanatized, weighed, scored for ascites, and heart, liver, and small intestine weights were obtained. Random samples were analyzed for intestinal ammonia. Blood samples were analyzed for blood gases, hemoglobin, red blood cell count, blood urea nitrogen, ammonia, and uric acid. Birds fed 125 and 250 ppm urease inhibitor were significantly (P < .001) lighter at 6 wk, when compared with controls. Urease inhibitor (125 and 250 ppm) significantly decreased large intestine ammonia. Urease inhibitor significantly increased small intestine (250 ppm) and liver weights (125 and 250 ppm), whereas urease inhibitor at 125 ppm decreased right ventricular heart weight. Urease inhibitor had no effect on ascites scores, blood gases, or blood ammonia, but hemoglobin, blood urea nitrogen, red blood cell count, and uric acid were significantly (P < .05) decreased by 125 ppm urease inhibitor.
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PMID:Effect of a urease inhibitor and ceiling fans on ascites in broilers. 2. Blood variables, ascites scores, and body and organ weights. 807 23


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