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

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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)

The activities of two types of antiulcer agents against 9 strains of Helicobacter pylori (H. pylori) were determined by the agar dilution method. The antiulcer agents were YJA20379, a newly synthesized proton pump inhibitor developed by Yung-Jin Pharmaceutical company, and omeprazole. Both compounds were found to have significant activities against this organism. The MIC values of YJA20379 and omeprazole were 11.7 and 31.25 micrograms/ml, respectively. In addition, the inhibitory potency of both compounds was investigated on H. pylori urease which is believed to be an important colonization and virulence factor in the pathogenesis of gastritis and peptic ulcers. These compounds dose-dependently inhibited urease extracted with distilled water and their IC50 values were 16.4 x 10(-5) M and 14.3 x 10(-5) M, respectively. In addition, a pH-dependent study to determine whether inhibitory potency would be activated by acid condition was performed. It was found that unlike omeprazole, YJA20379 was not affected by acid condition. To determine the inhibition pattern and optimal concentration of substrate, kinetics were evaluated at various pH levels (pH 5.0, 7.0, and 8.5). The data show that YJA20379 noncompetitively inhibited H. pylori urease and KM/Ki values were 0.96 mM/60 microM (pH 5.0), 0.56 mM/141.5 microM (pH 7.0), and 1.94 mM/34 microM (pH 8.5), respectively. Based on data obtained, it is concluded that YJA20379 is a significant inhibitor of H. pylori growth and urease and therefore, taking these results into consideration, YJA20379 might be a beneficial therapy for gastritis and peptic ulcers induced by H. pylori.
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PMID:Inhibitory action of YJA20379, a new proton pump inhibitor on Helicobacter pylori growth and urease. 987 7

The methods which require endoscopy for the examination of the gastric mucosa are called invasive (direct) methods. Several tests can be performed on the gastric mucosa obtained by endoscopy: Rapid urease test, histology, smear (cytology), culture and polymerase chain reaction. A combination of at least two tests with high sensitivity and specificity is recommended for clinical trials, and, when possible, for clinical management of patients. In clinical practice the invasive methods should be carried out only in those patients to be treated with eradication regimes. All invasive methods rely on gastric biopsy samples. Therefore, the specimens should be taken under optimal conditions. Several factors guide the site and the number of biopsy specimens for identification of Helicobacter pylori infection. In pre-treatment diagnosis, the biopsies should be taken from the distal antrum (2 cm from the pylorus). The number required depends on the diagnostic method used: in Helicobacter pylori eradicated patients the same number of biopsies for histology and culture should be taken from the antrum and corpus. The sensitivity and specificity of the Rapid urease test varies from 80-90% the results are known very quickly and the cost is very low. The maximal accuracy of histology is obtained with: an optimal specimen processing, an adequate staining and an experienced observer. This method of biopsy processing facilitates the identification of Helicobacter pylori which is commonly located on the superficial and foveolar epithelium. Sensitivity depends on the observer's experience and the extent of biopsy sampling. In general, the histological method has a sensitivity and specificity of 90-95%. In patients treated by proton pump inhibitors, antibiotics or bismuth salts two-four weeks prior to biopsy, the bacteria may be restricted to the corpus or fundus. Culture is strictly indicated in patients after failure of two or more eradication regimens to test for susceptibility and resistence. Specificity is 100% and sensitivity depends on the experience and interest of the microbiologist. The indication of polymerase chain reaction is only for research, specially, in molecular epidemiology and for fingerprinting.
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PMID:Diagnosis of Helicobacter pylori: invasive methods. 1007 65

Helicobacter pylori (HP) eradication reduces dramatically the peptic ulcer relapse rate, but information regarding recurrence of peptic ulcer bleeding after eradication is still scanty. Available data show rebleeding rates of 0-3% per year in successfully eradication patients, compared with figures between 12 and 33% among the non eradicated ones. The aim of this study was to determine the rebleeding rate among successfully eradicated patients with a prior history of rebleeding peptic ulcer. 42 patients (34 male, mean age 49, range 18-74) hospitalised for Hp positive bleeding peptic ulcer undergoing conservative treatment, were given as soon as oral route was re-established, a one-week eradication treatment, followed by the same proton pump inhibitor for three or five weeks for duodenal and gastric ulcer healing respectively. No maintenance antiulcer therapy was indicated. Patients were advised not to take nonsteroideal anti-inflammatory drug. Ulcer healing and Hp eradication was confirmed in all 42 patients by means of endoscopy and biopsies for urease rapid test and histology four weeks after completion of the treatment. After this patients were invited to enter a long-term follow-up program with periodical visits. End point of the study was occurrence of rebleeding. Further endoscopies were planned when rebleeding or symptomatic relapse. Median follow-up time was 24.02 months, ranging from 3 up to 27 months. All patients were compliant with the follow-up visits. None of the patients presented with symptoms suggestive of ulcer relapse or upper gastrointestinal bleeding. Our data suggest, that Hp eradication can prevent bleeding relapses in patients with Hp positive bleeding peptic ulcers.
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PMID:[Absence of bleeding recurrence of peptic ulcer after long term follow-up of successful eradication of Helicobacter pylori]. 1049 14

Rabeprazole sodium is a new substituted benzimidazole proton pump inhibitor with several differences compared with existing proton pump inhibitors. In vitro and animal studies have demonstrated that rabeprazole is a more potent inhibitor of H+,K(+)-ATPase and acid secretion than omeprazole, and is a more rapid inhibitor of proton pumps than omeprazole, lansoprazole, or pantoprazole. This probably reflects rabeprazole's faster activation in the parietal cell canaliculus. In human studies, once-daily doses of 5-40 mg of rabeprazole inhibit gastric acid secretion in a dose-dependent fashion. A once-daily dose of 20 mg has consistently achieved profound decreases in 24-h intragastric acidity in single and repeat dosing studies, in healthy volunteers and patients with either peptic ulcer disease or gastro-oesophageal reflux disease. Significantly greater decreases in intragastric acidity are achieved on day 1 of dosing with rabeprazole 20 mg than with omeprazole 20 mg. As with other proton pump inhibitors, rabeprazole has in vitro antibacterial activity against Helicobacter pylori, with greater activity against this organism than either lansoprazole or omeprazole. In addition to inhibiting bacterial urease activity, rabeprazole binds to several molecules on H. pylori. Clinical trials are needed to assess the clinical importance of these findings, as well as to assess whether the potential advantages of rabeprazole result in clinical benefit for patients with acid-related diseases.
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PMID:Review article: the pharmacology of rabeprazole. 1049 23

The diagnosis of peptic ulcer must be precise and based on both endoscopic examination (in the case of gastric ulcer to differentiate between benign or malign ulcers), and on bioptic examination. Peptic ulcer is pathogenetically associated with H. pylori. A small group of patients with duodenal ulcers and without H. pylori or without an other known cause (NSAID, etc.) is a poorly defined sub-group of patients. H. pylori has an important role in the pathogenesis of gastritis and bulbitis. Both states are involved in the pathogenesis of peptic ulcer. If H. pylori is eradicated, inflammatory changes of the gastric and duodenal mucosa recede and the recurrence of peptic ulcer decreases to a minimal size. For estimation of H. pylori, several invasive and non-invasive techniques are used. Among invasive methods most used in peptic ulcers, a combination of the rapid urease test and histology seems to be the most important. Among non-invasive methods, the breath tests are the most reliable. The treatment is focused on the eradication of H. pylori (no H. pylori is found one month or more after completed therapy). Of the eradication regimens, the triple therapy with proton pump inhibitors, claritromycin and metronidazole or amoxicillin are most effective. If this therapy fails, quadrutherapy (triple therapy combined with colloid bismuth subcitrate) may be successful. The precise diagnosis of peptic ulcer and H. pylori infection is a basic prerequisite for rational therapy of peptic ulcer disease and its relapses.
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PMID:[Peptic ulcer and Helicobacter pylori, diagnosis and therapy]. 1056 1

The prevalence of H. pylori infection has been reported to be very high in duodenal ulcer (DU) disease, but the precise frequency and causes of H. pylori-negative DU are not well known. In some geographical regions, however, a relatively low prevalence of the infection has been described. Our aim was to study the frequency and causes of H. pylori-negative DU and to evaluate whether empirical H. pylori eradication therapy without confirmation of the infection is justified. In all 774 consecutive patients with an endoscopic diagnosis of DU were studied prospectively. Exclusion criteria were associated diseases and previous gastric surgery. The use of NSAIDs, antibiotics (during the last month), and proton pump inhibitors (during the last month) was evaluated by means of a specific questionnaire. At endoscopy, two biopsies from both antrum and corpus were obtained in all 774 patients for histologic study (H&E stain). One sample from the antrum for rapid urease test, one sample each from the antrum and corpus for culture, and two duodenal biopsies for histologic study were also obtained in the first 307 patients. A [13C] urea breath test was carried out in the remaining 467 patients. Patients were considered infected if any of the diagnostic tests were positive and noninfected when all tests performed were negative. Age (mean +/- SD) was 46+/-12 years, 70% were males. NSAID, antibiotic, and proton pump inhibitor use was described, respectively, in 8.9%, 5.8%, and 6.3% of the cases. H. pylori infection was demonstrated, overall, in 95.3% (95% CI: 93.6-96.6%) of the patients. H. pylori prevalence increased up to 99.1% (98.1-99.6%) if patients taking NSAIDs and/or antibiotics were excluded. Among the 36 H. pylori-negative patients, 20 (55%) were taking NSAIDs, 9 (25%) were taking antibiotics, and 1 (3%) both of them. Therefore, in only 6/774 patients (0.8%) could DU disease be considered truly "idiopathic." Differences were demonstrated between H. pylori-positive and -negative patients (univariate study; chi2) with regard to NSAID intake (7% vs 58%; P < 0.0001) and previous antibiotic use (5% vs 28%; P < 0.0001). In the multivariate analysis (logistic regression), NSAID use (OR: 0.06; CI: 0.03-0.13; P < 0.001) and antibiotic use (OR: 0.23; CI: 0.09-0.59; P < 0.01) were the only variables that correlated with H. pylori infection. The most important factors associated with H. pylori-negative DU are NSAIDs and prior antibiotic use, and if these agents are excluded, the prevalence of infection in our area is as high as 99%. Therefore, in DU patients not taking NSAIDs and living in areas where previous studies have shown the prevalence of the infection in DU disease to be very close to 100%, empirical H. pylori eradication therapy without confirmation of the infection may be justified.
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PMID:H. pylori-negative duodenal ulcer prevalence and causes in 774 patients. 1057 77

A new triple therapy using a proton pump inhibitor and two antibiotics shows high efficiency against Helicobacter pylori infection. The aim of this study was to determine the optimal dose and duration of lansoprazole (LA) administration in combination with amoxicillin (AMPC) and metronidazole (MNZ). A total of 91 patients were enrolled in this study. They were divided into four groups: group A, 2 weeks of 30mg LA once daily, 500mg AMPC tid, and 250mg MNZ tid; group B, 2 weeks of 30mg LA bid, 500mg AMPC tid, and 250mg MNZ tid; group C, 1 week of 30mg LA once daily, 500mg AMPC tid, and 250mg MNZ tid; group D, 1 week of 30mg LA bid, 500mg AMPC tid, and 250mg MNZ tid. H. pylori status was determined by the rapid urease test, culture, histology, and 13C-urea breath test before and at least 4 weeks after the end of therapy. The cure rates in a per-protocol analysis and the incidence of adverse events in the evaluated patients were, respectively, 89.5% and 21.1% in group A, 100% and 20.0% in group B, 96.8% and 12.9% in group C, and 92.3% and 26.9% in group D. Most of the adverse events were tolerated. All four regimens in this study showed the same cure rates, and they were effective and well tolerated. One week of triple therapy using once-daily administration of 30mg LA is a good alternative.
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PMID:Eradication of Helicobacter pylori using 30 mg or 60 mg lansoprazole combined with amoxicillin and metronidazole: one and two weeks of a new triple therapy. 1061 70

The finding of II pylori in the gastric mucosa has changed the understanding of the pathogenesis of common diseases of the stomach and duodenum. The bacteria causes acute and chronic gastritis and is the precursor of peptic ulcers, gastric lymphoma and gastric cancer. The most common test used to diagnose the infection is the urease test on a gastric biopsy but an endoscopy must be performed to obtain the biopsy. Determination of serum levels of IgG appears the most suitable test to perform in large population studies. Patients with peptic ulcers, gastric lymphoma and early gastric cancer should be treated. Combinations of antibiotics such as amoxicillin, chlarithromycin and a proton pump inhibitor have yielded the best results in irradicating H pylori. Unfortunately this therapy is expensive and new combinations should be explored. Vaccination should be the treatment of choice for prevention and irradication in countries like Chile with high infection rate. Preliminary results are encouraging.
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PMID:[Helicobacter pylori. The bacteriological revolution]. 1075 48

Quadruple therapy (with a proton pump inhibitor (PPI), metronidazole, tetracycline and bismuth) is generally reserved for second-line treatment; however, studies using this regimen for 7 days have found it to be effective even in metronidazole-resistant strains. Resistance is an ongoing problem with antimicrobial therapy but considerable progress has now been made into understanding the underlying genetic mechanisms of this process. Metronidazole resistance in Europe is usually in the range of 20-30% of strains but may be as high as 70% in some countries. One genetic mechanism involved is thought to be a mutation of the rdxA gene. Macrolide resistance appears to be on the increase in Europe, varying from 1% in some countries to 13% in others. The genetic mechanism involved has been shown to be a point mutation of a ribosomal RNA. Amoxicillin resistance is an emerging problem that has an adverse effect on eradication rates in clinical practice. Resistance has been shown to be caused by the absence of one of the four binding proteins in the cell wall. Few novel antibiotics have been developed for use in eradication therapy, although rifabutin, secnidazole and furazolidone have shown some success as part of combination therapy. Alternative therapies that have been tested include mucosal protective agents which have been used in place of a PPI in some eradication regimens with some success, and the somatostatin analog, octreotide, that has been used as part of quadruple therapy in place of a PPI and produced eradication rates of approximately 88%. The ultimate challenge is still to develop a safe and effective vaccine against Helicobacter pylori. Current and future research will also focus on identifying genetic targets for therapy, adhesion molecule analogs to prevent binding of the bacterium, and urease inhibitors. The current triple therapy treatment options available for the eradication of Helicobacter pylori infection are over 90% effective in susceptible organisms and there are very few medical conditions to which we can offer such efficacious treatment. Unfortunately, the recommendations made at consensus conferences are not always put into practice and physicians in primary care may be unaware of the true efficacy of eradication therapy. Treatment is very simple: three drugs, twice a day for 1 week. The main focus for both primary care physicians and gastroenterologists should be to reinforce the need for patient compliance, otherwise we will see an increase in antibiotic resistance. Patients should be prewarned that they may experience some mild side effects and should be encouraged to complete the course of treatment. The real challenge for the future will be the management of patients who do not respond to first-line treatment. This paper will focus on potential problems with therapy, such as antibiotic resistance, and possible future solutions, such as novel antibiotics and vaccines.
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PMID:Challenges to therapy in the future. 1082 51

Infection with Helicobacter pylori induces humoral immune responses against various antigens of the bacterium. Heat shock proteins (hsps) are immunodominant antigens in various diseases including H. pylori infection. In the present study, we measured the anti-hsp antibody titers in 42 patients with H. pylori-infected peptic ulcers during a bacterial eradication study. The patients were treated with a proton pump inhibitor and antimicrobial agents to eradicate the organism. Their sera were obtained at pretreatment and at 1 month and 6 months after the eradication therapy. The titers of immunoglobulin G antibodies to the H. pylori hsp, whole-cell lysate, and urease (30-kDa subunit) antigens in serum were measured by a capture enzyme-linked immunosorbent assay. The levels of H. pylori hsp60 antibodies in sera collected 1 month after treatment had declined significantly, even when changes in the titers of antibodies to whole-cell and urease antigens were not apparent. These results suggest that measurement of antibodies to H. pylori hsp60 in serum is useful for the early monitoring of the effectiveness of eradication therapy.
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PMID:Antibody to heat shock protein can be used for early serological monitoring of Helicobacter pylori eradication treatment. 1088 54


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