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At least 1,189 records · Page 66Linked to original sources
PubMed2005

[A preliminary study of the modulation of Actinomyces naeslundii urease to the pH balance of dental biofilm].

PURPOSE: To explore whether the ureolysis of Actinomyces naeslundii could keep high level in the natural dental biofilm and the effect of ureolysis on the environmental pH balance preliminarily. METHODS: Enzyme kinetic test was used to detect the optimal condition for ureolysis; and the pH change was measured under ureolysis after acidgenesis.SPSS software package was used for linear regression and correlation analysis. RESULTS: The Km of urease was 7.5mmol/L, it could keep 20% to 63% of the optimal activity with the concentration of urea normally found in the mouth which was at the range of 3-10mmol/L; The optimal pH of ureolysis was 6.5, but at pH 5.0 which was the threshold pH of dental plaque, the enzyme had 40% of the optimal activity; with the concentration of urea normally found in the mouth, pH would not decrease to the threshold pH with ureolysis after acidification. CONCLUSION: In the dental plaque biofilm, A. naeslundii could ureolyze highly actively; ureolysis could moderate the pH balance of plaque significantly.

Actinomyces↗
PubMed2006

Prospective evaluation of a new "paper urease test" for ultra-rapid detection of Helicobacter pylori.

BACKGROUND: The purpose of this study was to determine the sensitivity, specificity, and positive and negative predictive values of a newly developed paper urease test (PUT) for ultra-rapid detection of helicobacter pylori (HP) in gastric mucosa. MATERIAL/METHODS: 100 patients (43 men) with a mean age of 57+/-6.8 years participated. Patients presenting for upper endoscopy with no recent exposure to HP-altering drugs were enrolled. Gastric biopsy specimens were tested by the PUT and histology methods, and then the patients underwent [13C] urea breath tests (UBT). HP was considered positive when either UBT or histology demonstrated it, and negative if HP was not detected in either UBT or histology. The PUT was reported at 15 minutes. RESULTS: 87 of 100 patients tested positive for HP. The PUT correctly identified 74 of 87 HP-positive and 13 of 13 HP-negative patients, yielding sensitivity, specificity, and positive and negative predictive values of 87%, 100%, 100% and 53.5%, respectively, in this population. CONCLUSIONS: Rapidly available and reliable results from the PUT can facilitate clinical decision prior to patient discharge from the endoscopy suite. We recommend PUT for screening of HP in endoscopy candidates, due to high specificity, rapid reaction, simplicity and low cost. A positive result shows a definite diagnosis, although a negative result needs further diagnostic methods.

Cost-Benefit Analysis↗
PubMed2006

[A non-invasive method of evaluation of Helicobacter pylori urease activity: its perfection and introduction to clinical practice].

The authors have developed a highly sensitive method of non-invasive diagnostics of Helicobacter pylori, the most frequent human infection. Detection of urease activity is based upon measurement of the degree of the elevation of stable 13C isotope content in exhaled air after administration of C-urea as a test reagent. The method has been scarcely applied in Russia because the test preparation, 13C urea had not been produced domestically until 2002. The method can be easily applied by any healthcare institution; however, it requires special equipment and trained personnel to perform measurement of 13C content in exhaled air samples using mass spectrometers. The article presents the first experience in clinical application of the method.

Adolescent↗
PubMed2006

Validation of a new, commercially available dry rapid urease test for the diagnosis of Helicobacter pylori infection in gastric biopsies.

BACKGROUND: To compare the accuracy and reaction time of a new dry rapid urease test (GUT test) with the CLO test and an independent gold standard in the diagnosis of Helicobacter pylori infection. To determine whether this new test can replace the CLO test in routine clinical practice. METHODS: We included consecutive patients in whom normal-sized gastric biopsies were taken in routine practice. six antral and three corpus biopsies were taken for determination of H. pylori infection. results of the GUT test were monitored after 15, 60 and 120 minutes of incubation. Results were compared with the standard CLO test and an independent gold standard (bacterial culture and histology). The results of the CLO test were also compared with the gold standard. RESULTS: 116 patients were recruited in the study: 60 were males and 56 females. The mean age was 59.3 years (range 14-89 years). Compared with the CLO test, the GUT test had a sensitivity of 76.7% and a specificity of 100% in 15 minutes. After 60 minutes the sensitivity of the GUT test increased to 95.3%, the specificity remained 100%. All positive results of the GUT test occurred before 60 minutes of incubation. Compared with the gold standard, the GUT test had a sensitivity and specificity of 97.4 and 96.1% respectively. The CLO test had a sensitivity of 97.4% and a specificity of 93.5%, when compared with the gold standard. CONCLUSION: The GUT test appeared to be a good and reliable alternative for the widely used Clo test in diagnosing H. pylori infection. The GUT test results were not yet reliable after 15 minutes, but all positive results occurred before 60 minutes of incubation. The test can best be read 60 to 120 minutes after endoscopy.

Adolescent↗
PubMed2006

Sensitivity and specificity of an in-house rapid urease test for detecting Helicobacter pylori infection on gastric biopsy.

We developed an in-house rapid urease test (iRUT) and evaluated the efficacy and the agreement of the iRUT and the cRUT compared with culture and histology for the detection of H. pylori infection. Five iRUT media were tested with H. pylori isolates and other bacteria. The most suitable iRUT medium was further evaluated for detection of H. pylori infection. Gastric biopsies from 120 patients were diagnosed by culture, iRUT, cRUT and histology. The results of the iRUT and cRUT were read at 30 minutes, 1 hour and up to 24 hours. A true positive result was either the culture or both the RUT (cRUT or iRUT) and the histological examination being positive. The sensitivity and specificity of the iRUT result at 30 minutes, 1 hour and up to 24 hours were 77.1% and 100%, 77.6% and 100%, and 94.1% and 94.2%, respectively. Values for the same parameters of cRUT were 87.5% and 100%, 89.8% and 100%, and 100% and 94.2%, respectively. The agreement between the iRUT and cRUT was very good (kappa values > or = 0.82). Our results indicate that the iRUT is a-sensitive, specific and cost effective test. It can be appropriately applied for detecting H. pylori infection in gastric biopsy specimens.

Biopsy↗
PubMedDate not supplied

Synthesis and serological interactions of H. pylori urease fragment 321-339 n-terminally immobilized on the cellulose.

Antigenic epitopes F8 (SIKEDVQF) and UB-33 (UreB fragment with residues 321-339: CHHLDKSIKEDVQFADSRI) in H. pylori urease that induces neutralizing antibody production were prepared on the cellulose plate from N- to C-terminus using CDMT as a coupling reagent. Reaction of both epitopes with sera of patients with medically confirmed atherosclerosis was studied. Strong, selective reactions of both peptides with some patients sera were observed.

Amino Acid Sequence↗
PubMedDate not supplied

[The pathogenesis of stomach and duodenal involvement in chronic opisthorchiasis. 1. The urease test].

The study using the urease test on mucous biopsies from the antral gastric part and from the duodenum of patients with chronic opisthorchiasis with endoscopic evidence of antral gastritis and gastroduodenitis, and from noninvaded patients with gastritis and duodenitis, some of them with the gastric or duodenal ulcers showed that the test was positive. The test was negative in both groups of patients when the mucosa of the gastric body was examined as well as in those without gastroduodenal pathology. It is supposed that in the both groups of patients gastroduodenal pathology was provoked by the colonization of the gastric and duodenal mucosa by gastric campylobacteria.

Adult↗
PubMed1990

Evaluation of a modified medium for the one hour urease test for Helicobacter pylori infection.

The biopsy urease test is a simple and rapid method for the diagnosis of Helicobacter pylori infection; results are obtained within 4 h to 24 h. Various modifications of the media used in this test have been tried, to improve the accuracy and speed of the test. We compared the yield obtained with two media: the standard Christensen's urea medium and a modified plain urea medium (without the nutrients glucose and peptone); the result was read upto 1 h. In the first 53 cases, culture was obtained when either of the media gave a negative result. There was no difference in false positives in the two media, while there were more false negatives with the plain urea medium (4) compared to the Christensen's medium (1). In the latter 69 patients, we determined the accuracy of the two media by obtaining culture in all cases. The Christensen's medium had a sensitivity of 100% and a specificity of 92.1%, while the plain urea medium had a sensitivity of 96.7% and a specificity of 92.1%. The speed of reaction in both media was similar. We conclude that the Christensen's urea medium gives accurate results even when read at 1 h; the plain urea medium gives similar results.

Biopsy↗
PubMed1989

[A rapid urease test in Campylobacter pylori colonization of the gastric mucosa].

Biopsies from the gastric mucosa (antrum, corpus) of 145 patients investigated by endoscopy were analysed for Campylobacter pylori. The results of bacteriological, histological, enzymatic and chemical methods were compared. Urease activity was determined both in biopsies (CLO-test) and in gastric secretion. Furthermore, the concentration of urea was measured in gastric secretion. 71% of gastritis, 86% of ulcus duodeni and 83% of ulcus ventriculi diagnosed by endoscopy produced positive histological and/or cultural results, while 100% of control persons exhibited negative for both parameters. The sensitivity of the CLO-test (n = 112) was 95% and its specificity 78% when compared with bacteriological and histological results. The majority of false positive results was due to delayed and incomplete reactions. However, when compared with endoscopic-histological results the specificity of the CLO-test was 100%. The results of a modification of CLO-test (without culture medium) were up to 5 hours comparable. There was no positive correlation between the concentration of urea in gastric secretion and the histological or cultural identification of Campylobacter pylori. However, the measurement of ammonia turned out to be promising (sensitivity 80%). None of the tests was sufficiently specific on its own, whereas a 100% specificity was achieved when both the CLO-test and the determination of ammonia in gastric secretion were performed.

Adult↗
PubMed1979

Rapid screening for urease inhibitors.

Two methods are described that are suitable for the rapid screening of compounds as urease inhibitors. The first utilizes an electrode sensitive to NH4+ ions; the second is dependent on pH rise. A feature of both is a direct readout of reaction rate.

Acetazolamide↗
PubMedDate not supplied

A solid phase urease-linked cellular immunosorbent assay for circulating polymorphonuclear binding immunoglobulin.

A cellular enzyme linked immunosorbent assay (CELISA) is reported for the detection of circulating polymorphonuclear granulocyte binding immunoglobulin (PBG) in patients' sera. The assay features a solid phase microtiter method in which the enzyme urease is fixed to the antihuman globulin conjugate reagent and uses 0.25 percent glutaraldehyde fixed normal human polymorphonuclear neutrophils (PMNs) as target cells. The assay gave positive results in four of 13 (31 percent) cases of idiopathic neutropenia in which an autoimmune etiology was suspected and one typical case of isoimmune neonatal neutropenia. In a group of 15 patients receiving multiple blood transfusions for chronic anemia, five (33 percent) showed significantly higher levels (p less than 0.001) of PBG than non-transfused normal donors. The PBG-CELISA appears potentially useful for the detection of autoimmune and isoimmune PMN antibodies and PMN binding IgG immune complexes.

Antigen-Antibody Complex↗
PubMed1987

Comparison of biopsy urease test and histologic examination for detection of campylobacter pylori in duodenal, antral and fundic biopsies.

The presence of Campylobacter pylori was investigated in duodenal, antral and fundic biopsies of 149 consecutive patients undergoing upper gastrointestinal tract endoscopy by biopsy urease tests (CLOtest; "CLO test") and histologic examination ("HIST") after modified Giemsa staining. Positive results were obtained rarely in the duodenum (4.7% and 12.8% by CLO test and HIST, respectively), but equally frequently in antral (48.3% and 62.4%) and fundic biopsies (55.0% and 54.4%). Using combined evaluations ("COMB") of both CLO test and HIST results, and disregarding isolated positive histologic grades "1" as C. pylori negative, the detection rates were 6.0, 53.0 and 56.4% in the above order and 63.1% overall at any of the biopsy sites. There was no close correlation between the rapidity of the color conversion of the biochemical test and the microscopic grading of C. pylori density. A positive CLO test in single antral biopsy specimens was an accurate predictor of the presence of C. pylori as compared with HIST (predictive value positive PVpos 0.97), while negative antral BUT results did not rule out C. pylori colonization of the upper GI tract (PVneg 0.52 compared with HIST). An additional negative CLO test from fundic biopsies increases the PVneg to 0.58.

Adolescent↗
PubMed1979

The isolation of urease-negative strains of Yersinia enterocolitica.

Three urease-negative Y. enterocolitica strains of biotype 2 have been isolated from stool and urine of healthy persons. They were diagnosed on an isolation medium used routinely in the bacteriological laboratory of the Regional Station of Hygiene in Ceské Budĕjovice for isolation and diagnosis of gram-negative facultatively anaerobic-fermenting rods. An important characteristic was the smell of the culture, typical of all the indole-positive strains of Y. enterocolitica.

Adult↗
PubMed1983

[Prevention of infected urinary stones by urease inhibitor. IV. Treatment of infection stones in rats by a new hydroxamic acid and cefalexin].

We investigated the combined effectiveness of a new urease inhibitor, N-( pivaroyl ) glycinohydroxamic acid, with Cefalexin in the treatment of infection stones in rats. Combination therapy with the hydroxamic acid and Cefalexin inhibited bladder stone formation, and dissolved the stone dose dependently, while separate therapy was not significantly effective against stone formation or bacterial growth. This compound may become a useful medicine for the treatment of infection stones.

Animals↗
PubMedDate not supplied

Inhibition of the growth of Ureaplasma urealyticum by a new urease inhibitor, flurofamide.

Flurofamide (N-[diaminophosphinyl]-4-fluorobenzamide), a urease inhibitor, was a potent inhibitor of the growth of Ureaplasma urealyticum. As little as 10 microM flurofamide (2 micrograms/ml) prevented any growth, but U. urealyticum survived for about eight hours before colony counts become undetectable. Flurofamide was a specific inhibitor of U. urealyticum since it did not inhibit growth of four Mycoplasma species or Acholeplasma hippikon. Flurofamide was 1,000 times more active than acetohydroxamic acid and thus has promise as a chemotherapeutic agent and a biochemical tool.

Acholeplasma↗
PubMed1984

[Rapid method for the simultaneous determination of bacterial urease and phenylalanine desaminase].

Tested was an accelerated method for the evaluation of urease and phenylalanine desaminase of a total of 327 strains of E. coli, S. typhimurium, S. enteritidis, S. braenderup, S. tennessee, P. vulgaris, P. mirabilis, Yersinia enterocolitica, and Citrobacter that were subjected to a preliminary identification with routine methods. It was established that the method tested had the following advantages as compared to the classical methods employed up to then in the laboratory practice: --100% positive results were obtained up to the 4th hour, i. e. the method appeared 6 times more rapid, and the overall result was obtained one day earlier; --the two enzymes were studied simultaneously; --the expenditures in connection with the use of nutrient medium per one test were several times lower. Suggested is the timely adoption of the accelerated method in the laboratory practice.

Amino Acid Oxidoreductases↗
PubMed1978

[Specific protection by sulfhydryl groups against inhibition of urease by hypoglycaemic drugs (author's transl)].

The effect of oral hypoglycaemic drugs, derivatives of sulphonylurea, upon urease has been studied. These compounds, structurally connected to urea, produce a competitive inhibition of enzyme activity with respect to substrate. Glutathioné (reduced form) and cysteine prevent inactivation of enzyme by sulphonylurea, whereas-oxidated glutathione and cysteine do not. The same phenomenon occurs in enzyme preparations inhibited by p-hydroxymercuribenzoate. The role of sulfhydryl groups in the formation of enzyme-substrate complex is discussed.

Chlorpropamide↗