Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “UREASE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28Linked to original sources
PubMed1991

Research note: increased growth of chicks and poults obtained from hens injected with jackbean urease.

Two experiments were conducted using 120 Single Comb White Leghorn (SCWL) hens and 40 turkey hens. Hens were randomly assigned to two treatments: those injected with urease and controls injected only with adjuvant. At 22 wk of age, half of the SCWL hens were injected intramuscularly with 12 Sumner units of jackbean urease suspended in incomplete adjuvant six times in 26 wk. Turkey hens were injected twice at weekly intervals with 70 Sumner units. The other half of the breeders received adjuvant without urease (control). Urease injection into SCWL hens had no effect on feed consumption, feed conversion, and percentage fertility, hatchability, and hatch of all eggs set, but egg weight and body weight of chicks at hatch and at 3 wk of age were significantly higher as compared with the control hens. In the case of turkey hens, percentage hatchability and progeny body weight were significantly higher as a result of urease injection.

Animals↗
PubMedDate not supplied

[Synthesis and study of the properties of water-insoluble products of the interaction of urease and cellulose derivatives].

As a result of reaction of urease with graft copolymer of cellulose and polyglycidyle methacrylate or with carboxymethyl cellulose, products were synthesized, containing about 2% of chemically bound urease. Binding with the cellulose derivatives was accompanied by about two-fold decrease in urease activity. Carboxymethyl cellulose-urease and polyglycidile methacrylate-cellulose-urease might be repeatedly (for 30 cycles) used for hydrolysis of urea; the enzymatic activity of the first compound did not change, but of the second one--was decreased by 30%. Activity of the compounds was not changed after storage within 2 months in 0.1 M phosphate buffer, pH 7.0 at 4 degrees C.

Acrylates↗
PubMed2002

[Effects of mercury and cadmium on the activity of urease in soils. I. Urea concentration].

Relationship between urease activity and heavy metals(Hg and Cd) under the condition of different urea concentration was studied. The results showed that the added urea concentration had an obvious positive effect on urease activity. Line and Langmuir models could be well described the relationship within the urea concentration tested. The calculation of urease parameters such as urea percent, urea-varying percent, and the maximum superficial urease activity reflected that Hg and Cd could remarkably reduce the positive effect from added urea, combined pollution of Hg + Cd displayed the most inhibition of the positive effect, and Hg produced the most ecological toxicity acting on soil urease activity. There was an adsorption mechanism in the enzyme reaction.

Cadmium↗
PubMed2002

Evaluation of inhouse rapid urease test for detection of Helicobacter pylori from gastric biopsy specimens.

Inhouse rapid urease test for detecting Helicobacter pylori was evaluated. Biopsy specimens were taken for inhouse urease test, commercial rapid urease CLO test, culture, gram stain and histology from the antrium or duodenum of patients who had peptic ulcer. The culture and/or histologic examination and CLO test were used as the gold standard. One hundred and twelve specimens were evaluated. The sensitivity and specificity of the inhouse urease test was 100 per cent and 90 per cent respectively. The inhouse urease test was suitable for detecting Helicobacter pylori from gastric antral biopsy specimens. The medium can be kept in a refrigerator for up to 6 months.

Biopsy, Needle↗
PubMedDate not supplied

[Polyphenolic antioxidants efficiently protect urease from inactivation by ultrasonic cavitation].

Inactivation of urease (25 nM) in aqueous solutions (pH 5.0-6.0) treated with low-frequency ultrasound (LFUS; 27 kHz, 60 Wt/cm2, 36-56 degrees C) or high-frequency ultrasound (HFUS; 2.64 MHz, 1 Wt/cm2, 36 or 56 degrees C) has been characterized quantitatively, using first-order rate constants: kin, aggregate inactivation; kin*, thermal inactivation; and kin* (US), ultrasonic inactivation. Within the range from 1 nM to 10 microM, propyl gallate (PG) decreases approximately threefold the rate of LFUS-induced inactivation of urease (56 degrees C), whereas resorcinol poly-2-disulfide prevents this process at 1 nM or higher concentrations. PG completely inhibits HFUS-induced inactivation of urease at 1 nM (36 degrees C) or 10 nM (56 degrees C). At 0.2-10 microM, human serum albumin (HSA) increases the resistance of urease (at 56 degrees C) treated with HFUS to temperature- and cavitation-induced inactivation. Complexes of gallic acid polydisulfide (GAPDS) with HSA (GAPDS-HSA), formed by conjugation of 1.0 nM PGDS with 0.33 nM HSA, prevent HFUS-induced urease inactivation (56 degrees C).

Antioxidants↗
PubMed2003

[Endurance and mechanisms of soil urease and dehydrogenase exposed to reactive X-3B red dye contamination].

Endurance and mechanisms of urease and dehydrogenase in three Chinese typical soils (burozom, cinnamon soil and red soil) exposed to the contamination of reactive X-3B red dye were experimentally studied using the microcosmic method. The results indicated that the activities of urease and dehydrogenase were both promoted in the three soils by reactive X-3B red dye in low dose, 500 and 1000 mg/L although the stimulating intensity was different from each other. For one thing, the activity of urease in burozom was promoted mostly followed by that in red soil and that in cinamon was promoted most weakly. For the other, reactive X-3B red dye in the same concentration could increase the activity of dehydrogenase in cinnamon soil most greatly and in burozom most weakly. However, the stimulating intensity of urease and dehydrogenase activities in the three soils was more and more fainter with the extension of days. Furthermore, reactive X-3B red dye in high concentration (3000, 5000 and 10,000 mg/L) could not inhibit the activities of urease and dehydrogenase in tested soils. On the contrary, all of them remained the level of the activities in unpolluted soils and no toxicity of reactive X-3B red dye could reveal with time. Therefore, both enzymes in three types of soils had the tolerance to reactive X-3B red dye. Based on the experimental data, relevant endurant mechanisms were also analyzed and discussed.

Coloring Agents↗
PubMed1992

Helicobacter pylori infection and gastroduodenal disease: a comparison of endoscopic findings, histology, and urease test data.

To determine the prevalence and significance of Helicobacter pylori (H. pylori) infection, biopsies of the antral mucosa were obtained from 139 patients and 43 asymptomatic volunteers. The specimens were examined by hematoxylin-eosin staining and the ureas test. The detection rate of H. pylori by histologic examination was 91.3% in patients with duodenal ulcer, 75.0% in those with combined duodenal and gastric ulcer, 63.6% in those with gastric ulcer, 22.9% in those with gastric carcinoma, 36.4% in those with gastric adenoma, 14.3% in those with gastric hyperplastic polyp, and 51.7% in those with gastritis, and the respective percentages detected by the urease test were 91.3%, 75.0%, 54.5%, 28.6%, 27.3%, 14.3%, and 44.8%. H. pylori was also detected in 10/43 (23.3%) asymptomatic healthy volunteers by histology and the urease test. The prevalence of H. pylori was significantly higher in the patients than in the asymptomatic healthy volunteers (p < 0.05). H. pylori was detected in 62.9% of patients with endoscopic erosive gastritis and in 97.9% of those with histologically proven chronic active gastritis. The urease test was positive in 77/82 patients who were histologically positive for the organism (sensitivity: 93.9%), and it was negative in 98/100 patients who were negative by histology (specificity: 98.0%). Thus, there was over 90% agreement between the urease test and histology. Our investigations showed that H. pylori was closely related to peptic ulcers and antral gastritis, and that the urease test provides a simple, rapid and accurate diagnosis of H. pylori infection.

Adult↗
PubMed1992

[An urease negative Cryptococcus neoformans].

We report an urease negative Cryptococcus neoformans derived from pigeon dropping. This isolate produced brown pigmented colonies on cornmeal Tween-80 agar with 300 micrograms/ml caffeic acid, but was failure to hydrolyze urea. More identification tests were performed for this isolate, such as assimilation and fermentation of carbohydrates, nitrate assimilation, production of starch like compound, growth on GCP medium, germ tube formation and inoculation of mice, ect. Most of the results showed that the microbiological characteristics of the isolate were typical of C. neoformans except for negative urease test. Even though there has been a report about an urease negative C. neoformans derived from an AIDS patient, but we have never found any report about isolation from pigeon dropping or nature environment. We should pay attention to the exist of this atypical strain of C. neoformans in nature environment and the possibility of infection to human being. Additionally, we also be aware of the possibility of neglect when this urease negative C. neoformans is identified with urease test.

Animals↗
PubMed2003

[Dynamics of urease activity in a long-term fertilized black soil and its affecting factors].

The effect of long-term fertilization on the urease activity in a typical black soil in Northeastern China was examined in this paper. The soil has been fertilized since 1980, and the dynamics of its urease activity was monitored during crop growth season. The results showed that a significant difference in soil urease activity was found at each growth stage between soils treated by different fertilizations. In farmyard manure treated soil, the urease activity was > 160 mg.kg-1.h-1 and with a low seasonal fluctuations. The soil urease activity had a significant positive correlation with soil biological, physical and chemical properties, and the N, P and K contents in plants (P < 0.01), and with soil moisture content and grain crude protein (P < 0.05).

Fertilizers↗
PubMed2004

[Effect of arsenic on soil urease activity].

By simulation method, this paper studied the urease activity in arsenic polluted soils. The results showed that arsenic could activate soil urease activity after added for one year. With arsenic addition, soil urease activity remarkably increased, and there existed a significantly positive correlation. The Vmax of soil urease increased with arsenic addition, while the Km of urease in high and low fertility soil was unchanged and slight increased, respectively. It is proved that As could accelerate the separating velocity of enzyme-urea complexes. This paper also illustrated that soil properties were important to study the relationship between soil enzyme and pollutants.

Arsenic↗
PubMedDate not supplied

[Comparative study between rapid urease test, imprint and histopathological study for Helicobacter pylori diagnosis].

Helicobacter pylori infection is relevant, due to its role in different gastric pathologies; there are several diagnostic methods, which are divided into invasive and non-invasive. In the first category histology has been considered the gold standard, while other methods include imprint with Gram stain and rapid urease test, which can produce dependable results. The aim of this study is to compare several available techniques for H. pylori diagnosis to know their sensitivity and specificity. We studied 88 patients, 50 women and 38 men, with age range from 17 to 83 years (48.8+/-14.3) from the Endoscopy Department of the 20 de Noviembre Medical Center; in all five to eight biopsies were taken from gastric mucosa to perform rapid urease test, Gram-stained imprint and histology. Endoscopic findings included gastritis (87.50%), pangastritis (2.30%) and another diagnoses (10.22%). Rapid urease test was positive in 40 patients and negative in 48, while imprint was 34 and 54, respectively. Sensitivity and specificity were as follows: rapid urease test, 84.8 and 78.5%, and imprint 75.8 and 83.6%, respectively. In conclusion, H. pylori diagnosis by rapid urease test is a dependable and quick method. On the other hand, imprint is useful but depends on the ability of the personnel who perform the test.

Adolescent↗
PubMed1991

Reactivity of the essential thiol of Klebsiella aerogenes urease. Effect of pH and ligands on thiol modification.

The kinetics of Klebsiella aerogenes urease inactivation by disulfide and alkylating agents was examined and found to follow pseudo-first-order kinetics. Reactivity of the essential thiol is affected by the presence of substrate and competitive inhibitors, consistent with a cysteine located proximal to the active site. In contrast to the results observed with other reagents, the rate of activity loss in the presence of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) saturated at high reagent concentrations, indicating that DTNB must first bind to urease before inactivation can occur. The pH dependence for the rate of urease inactivation by both disulfide and alkylating agents was consistent with an interaction between the thiol and a second ionizing group. The resulting macroscopic pKa values for the 2 residues are less than 5 and 12. Spectrophotometric studies at pH 7.75 demonstrated that 2,2'-dithiodipyridine (DTDP) modified 8.5 +/- 0.2 mol of thiol/mol of enzyme or 4.2 mol of thiol/mol of catalytic unit. With the slow tight binding competitive inhibitor phenyl-phosphorodiamidate (PPD) bound to urease, 1.1 +/- 0.1 mol of thiol/mol of catalytic unit were protected from modification. PPD-bound DTDP-modified urease could be reactivated by dialysis, consistent with the presence of one thiol per active site. Analogous studies at pH 6.1, using the competitive inhibitor phosphate, confirmed the presence of one protected thiol per catalytic unit. Under denaturing conditions, 25.5 +/- 0.3 mol of thiol/mol of enzyme (Mr = 211, 800) were modified by DTDP.

2,2'-Dipyridyl↗
PubMedDate not supplied

[Properties of urease immobilized by chemical binding to a derivatives of cellulose].

A comparative study of properties of soluble urease and urease immobilized by its binding to cellulose derivatives was carried out. Upon chemical binding of urease to cellulose derivatives the Mikhaelis constant and pH optimum for the enzyme action changed insignificantly. Maximum enzymic activity of soluble and immobilized urease occurred at 50 degrees C. The energy of activation of urea hydrolysis by urease during enzyme immobilization also changed insignificantly.

Catalysis↗
PubMed1989

[Campylobacter pylori: diagnostic value of the urease test during endoscopy].

The aims of this prospective study were a) to evaluate the diagnostic value of the urease test for the detection of C. pylori in gastric biopsy specimens, b) to specify the prevalence of C. pylori in a sample of 74 patients from the Grenoble area undergoing upper gastrointestinal endoscopy, c) to analyze the density of bacteria according to the biopsy site (antrum, body, edges of ulcer), d) to demonstrate any possible correlation between the histologic state of the antral and body mucosa and the presence of C. pylori. An antral biopsy was taken for the urease test during endoscopy. Biopsies were also taken from the body, the antrum and the edges of gastric or duodenal ulcers for bacterial and histologic studies, and urease test in the bacterial laboratory. The sensitivity and the specificity of the urease test during endoscopy varied according to the delay in observation of the color change. They were 0.81 and 0.84, respectively, at 2 h 30. The sensitivity and specificity of the urease test in the bacterial laboratory were 0.67 and 0.95, respectively, for the same delay. The global prevalence of C. pylori was 51 p. 100: it was 42 p. 100 in the absence of ulcer, 67 p. 100 in the presence of gastric ulcer, and 71 p. 100 in the presence of duodenal ulcer (p less than 0.05 compared to the group without ulcer).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[The effects of biotin on the metabolism of ammonia and amino acids in urease-induced hyperammonemic rats].

The effects of oral and intraperitoneal administration of biotin in urease-induced hyperammonemic rats, as well as the influence of biotin deficiency, have been studied. Biotin deficiency was produced by feeding standard diet MF (Oriental Yeast Co.) supplemented with dry egg-white (egg-white group). Egg-white + biotin group had free access to 0.0014% of biotin solution at all time. Following an intraperitoneal injection of urease, 25 U/kg (B.W.), plasma ammonia levels in egg-white + biotin group were lower than in egg-white group, especially there was significance (p less than 0.05) at 8 hours after the urease injection. Similarly, plasma ammonia levels in biotin-injected rats, in which 1 mg of biotin had been injected intraperitoneally prior to the experiment, were significantly low compared with saline-injected controls at 4 and 6 hours after urease administration. Results of plasma amino acid analysis, 9 hours after the urease injection indicated that Fischer's molar ratio (Leu + Ileu + Val/Tyr + Phe) was significantly higher in the biotin-injected rats than the saline-injected control. It suggests that biotin might decrease blood ammonia by facilitating the detoxification mechanism as follow: L-glutamate + NH3----L-glutamine.

Amino Acids↗
PubMed1988

[Production of immobilized urease adsorbed on polystyrene granules].

We prepared adsorption immobilized Urease (E.C. 3.5.1.5) with a special method of polymer coating of polystyrene granulate as a matrix, and by subsequent adsorption of two different urease products (AWD Dresden, DDR, 3 U/mg, and Serva, Heidelberg, BRD, 41 U/mg). We obtained the strongest activity (4.0 mumol.g-1.min-1) with immobilisates on polystyrene in comparison with polyvinylchloride, and polyurethane layers, if we used AWD urease (PS, PVC, PUR). By using Serva urease we obtained products with a manyfold of activity (12.8 mumol.g.min-1). This high activity enables us to utilize adsorption immobilized urease for the detoxification of biological fluids.

Ammonia↗
PubMed1987

Location of the essential cysteine residue of jack bean urease.

Jack bean urease is inactivated by the modification of about one cysteine residue per subunit with N-ethylmaleimide (NEM) or other thiol titrant. The location of this cysteine residue was identified. After blocking the unessential thiol groups with NEM, the essential cysteine was labeled with N-(4-dimethylamino-3,5-dinitrophenyl)maleimide (DDPM). The DDPM-labeled protein was cleaved with cyanogen bromide and a DDPM-fragment was purified by gel filtration and ion exchange chromatography. Amino-terminal amino acid sequence of the DDPM-labeled fragment corresponded to that of a cyanogen bromide fragment of urease, VCHHLDREIPEDLAFAHSRIRKKTIAAEDVLNDIGAISIISSDSQAM. The second residue, Cys-592 in native urease, was labeled with DDPM. Fluoride ion, which competitively inhibits urease activity, protected urease from inactivation by NEM. The dissociation constant of fluoride ion obtained from the rate of inactivation with NEM was essentially identical to both the kinetically and spectrophotometrically determined dissociation constants. These suggest that the essential cysteine is at or near the active site.

Amino Acid Sequence↗
PubMed1993

[Polymorphism of Helicobacter pylori urease genes and gastric diseases].

Helicobacter pylori (HP) is now recognized as a major etiologic agent of chronic gastritis and peptic ulcer and is recently presumed to be a cofactor in the occurrence of gastric cancer. HP has a high urease activity, which possibly plays a role in the pathogenesis of gastroduodenal diseases. In this paper, the function and the genetic structure of HP urease gene and the restriction fragment length polymorphism (RFLP) among HP strains using a probe of HP urease alpha subunit gene were described. HP urease gene cluster, which included structure genes, regulatory genes and accessory genes was identified and associated with the activity and the assembly. The RFLP pattern of HP tends to be distinct in gastric diseases, 460 bp pattern in gastric ulcer and 1,100 bp pattern in chronic gastritis, by Hae III digestion. HP showing a 460 bp RFLP pattern possessed a relatively high urease activity.

Amino Acid Sequence↗