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)

In order to provide a basis for obtaining further information concerning the host response to Helicobacter pylori urease, four assay methods for detecting urease-inhibiting activity in serum were examined. A quantitative assay, established in a COBAS BIO centrifugal fast analyzer and based on detection of the consumption of NADH by glutamate dehydrogenase stimulated by ammonia production, was considered most suitable for large-scale serological work. Serum samples from 63 children (aged 5 to 16 years), 28 of whom had seropositive H. pylori gastritis, were assayed. One of the serum samples in this latter group showed significant inhibitory activity. This serum sample was one of 13 in the seropositive group known to bind to urease antigen. It showed no inhibitory activity against Bacillus pasteurii or jack bean urease. Protein A binding and heat treatment indicated that the inhibitory activity was immunoglobulin G mediated. The patient from whom this sample was collected showed no distinctive features in his illness. The COBAS BIO analyzer-based urease inhibition assay provides a new tool for studying one aspect of the host response to H. pylori infection.
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PMID:Assay of urease-inhibiting activity in serum from children infected with Helicobacter pylori. 158 44

A total of 160 adult Malawians with epigastric pain for longer than 2 weeks was investigated by endoscopy and serologically for evidence of infection with Helicobacter pylori. The organism was demonstrated histologically and/or by culture in 141 (88%) patients. With histological means and/or culture as the 'gold standard', the histological technique was 100% sensitive while culture was only 81% sensitive. All isolates tested were sensitive to amoxycillin and tetracycline; 74% were resistant to metronidazole. Endoscopic findings were normal in 104 (65%) patients (86.5% H. pylori positive). Evidence of duodenal ulcer was found in 41 (25%) patients (95% H. pylori positive). Histologically, gastritis was common, severe gastritis being associated with increased colonisation by H. pylori. Two kinds of urease test were found to be 100% specific for the presence of H. pylori. The sensitivity of the serological test (Helico-G test) was 98% but its specificity was only 27%. These results provide important background information for planned therapeutic studies in patients with upper gastro-intestinal disease in Malawi.
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PMID:Helicobacter pyrlori in Malawi, central Africa. 160 48

The authors studied the role of Helicobacter pylori at recurrent abdominal pain in childhood. Helicobacter pylori infection hasn't been found at the 42 examined children. The endoscopy showed esophagitis in 34 cases. The quick urease test, the histological examination, and the bacterial culture are proposed to carry out in ulcus duodeni, gastritis typ. B ulcus ventriculi and not necessary to carry out if the endoscopy shows only esophagitis--emphasize the authors.
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PMID:[Studying the role of Helicobacter pylori infection in recurrent abdominal pain in children]. 160 7

'Gastrospirillum hominis' is a 'new' tightly coiled gram-negative bacterium carrying bundles of sheathed polar flagella. It has been rather infrequently detected in antral and, even more rarely, in fundic mucosa samples removed at endoscopy from patients investigated for Helicobacter pylori colonization. Until now, it has remained noncultivable but has successfully been maintained in laboratory mice. Its identity with similar bacteria found in the stomachs of cats, dogs, monkeys, pigs, and other animals is uncertain. It was probably already seen by early investigators in the first half of this century. Preliminary data published in case reports suggest that it is associated with more or less active chronic antral gastritis, that it is restricted to the gastric epithelium, and that it possesses a urease, thus limiting the specificity of urease tests for H. pylori. There is hitherto no solid proof that it can induce inflammation although it seems capable of invading parietal and other glandular cells and causing ultrastructural changes. Similar organisms spontaneously colonizing the stomachs of rhesus monkeys were shown to increase gastric acid secretion.
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PMID:'Gastrospirillum hominis', another gastric spiral bacterium. 161 10

Helicobacter pylori, a gram-negative, microaerophilic, spiral-shaped bacterium, is an etiologic agent of human gastritis and peptic ulceration and is highly restricted to the gastric mucosa of humans. Urease, synthesized at up to 6% of the soluble cell protein, hydrolyzes urea, thereby releasing ammonia, which may neutralize acid, allowing survival of the bacterium and initial colonization of the gastric mucosa. The urease protein is encoded by two subunit genes, ureA and ureB; however, accessory genes are necessary for enzyme activity. H. pylori urease genes were isolated from a cosmid gene bank and subcloned on a 5.8-kb Sau3A partial fragment carrying ureCDAB, corresponding to four open reading frames described by A. Labigne, V. Cussac, and P. Courcoux (J. Bacteriol. 173:1920-1931, 1991). Clones were confirmed as ureas gene sequences by polymerase chain reaction amplification. The recombinant enzyme was purified from the soluble protein of French press lysates of Escherichia coli DH5 alpha(pHP402) by chromatography on DEAE-Sepharose, Phenyl-Sepharose, Mono-Q, and Superose 6 resins. Fractions containing a catalytically inactive apoenzyme were identified by an enzyme-linked immunosorbent assay (ELISA) by using antisera to native UreA (29.5 kDa) and UreB (66 kDa). Purified recombinant urease was indistinguishable from native enzyme on a Superose 6 column and on Coomassie blue-stained sodium dodecyl sulfate-polyacrylamide gels. The protein reacted specifically on Western blots (immunoblots) with anti-UreA and anti-UreB antibodies and was recognized with an intensity equal to that of the native enzyme in an ELISA using human sera. Clones containing only ureA and ureB also produced an assembled but inactive enzyme. Enzyme activity was not restored by in trans complementation with cloned urease accessory gene sequences from Proteus mirabilis or Morganella morganii. H. pylori urease genes (ureCDAB) subcloned into pACYC184 were also not complemented with any of 1,000 cosmid clones containing H. pylori chromosomal sequences. However, larger clones containing 4.5 kb of DNA downstream of ureB synthesized catalytically active urease when grown in minimal medium. These data indicate that the ureA and ureB genes encoding H. pylori urease are transcribed and translated in E. coli and that these genes alone are sufficient for the synthesis and assembly of the native size enzyme. Genes downstream of ureB, however, are necessary for production of a catalytically active urease.
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PMID:Purification of recombinant Helicobacter pylori urease apoenzyme encoded by ureA and ureB. 161 35

Helicobacter pylori (H. pylori) is a small Gram negative bacillus, recently discovered, found in the stomach of patients with active chronic gastritis and duodenal ulcers. Production of a potent urease has been described as a trait common to all H. pylori so far isolated. To clarify the role of urease in the pathogenic process, as well as to engineer genetic tools useful for the diagnosis of H. pylori, we cloned the genes responsible for urease activity. A genomic library was constructed in Escherichia coli (E. coli) from the chromosomal DNA of the H. pylori stain 85P using a shuttle cosmid vector that we constructed in vitro capable of replicating both in E. coli and Campylobacter jejuni (C. jejuni). The genes responsible for the urease biosynthesis were cloned into E. coli host, then mobilized into C. jejuni where they were expressed. At least six different genes were shown to be required for the expression of the synthesis of an active enzyme: these genes belong to the same cluster and are regulated at the transcriptional level. The two genes encoding the two subunits of the urease enzyme were identified and sequenced; the products of these genes were compared to be other bacterial ureases. The genetic approach allowed to determine the amino-acid sequence of the most immunogenic antigens of H. pylori. In addition, it provides us with genetic tools: a 294-base pairs (bp) DNA fragment internal to one of the urease genes, was shown to be specific of H. pylori strains.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Development of genetic and molecular approaches for the diagnosis and the study of the pathogenic power of Helicobacter pylori, agent of inflammatory gastric diseases]. 162 9

Helicobacter pylori (H. pylori) is now accepted as an important cause of chronic active gastritis. There also seems to be an association between the colonization of H. pylori in the gastric mucosa and peptic ulceration. However, it has not demonstrated that the instillation of H. pylori into the stomach produces the ulcerative gastric lesions in animals or humans. We carried out an experiment to study whether or not H. pylori has an ulcerogenic action in the ischemic stomach of rats, using an ex vivo gastric chamber. The rat stomachs were exposed to 1 ml of H. pylori solution (200 IU of urease/ml) and 1 ml of urea (400 mg/dl) for 60 min after the creation of ischemia in the stomach (by withdrawal of 3 ml of blood). The exposure of the stomach to both H. pylori and urea resulted in severe hemorrhagic gastric mucosal lesions with a marked decrease in potential difference (PD) with a concomitant increase in ammonia concentration in rats with ischemia, whereas gastric lesions and a fall in PD were hardly observed in rats without ischemia. These results have demonstrated that H. pylori has an ulcerogenic action on the stomach subjected to mucosal ischemia.
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PMID:Helicobacter pylori has an ulcerogenic action in the ischemic stomach of rats. 162 66

Helicobacter pylori (HP) are Gram-negative spiral bacteria which occur in the human stomach. The bacteria were cultured in vitro for the first time in 1983. It is suspected that the bacteria may cause chronic gastritis of type B and may also be a contributory cause of chronic ulceration and cancer of the stomach. The bacteria are accompanied by characteristic inflammatory changes in the gastric mucosa. The significance for gastritis, chronic ulceration, non-ulcer dyspepsia and carcinoma of the stomach is discussed. HP occurs in a great proportion of the population of the world and the frequency increases with age. The route of infection is unknown but faecal-oral infection is probable. Correlation between the presence of HP and the occurrence of symptoms is poor in the individual patient. The bacteria can be demonstrated histologically, cytologically, by culture, by the urease test, by the urease expiration test or serologically. The bacteria are sensitive for a series of antibiotics and bismuth but no effective treatment is known as the recurrence rate is high.
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PMID:[Helicobacter pylori]. 163 4

The importance of pro-inflammatory leukotriene C4 in Helicobacter pylori (H. pylori) associated gastritis in man is unknown. Fresh gastric biopsy specimens from 28 dyspeptic patients were obtained: 10 showed normal antral histology with no evidence of H. pylori, the remaining 18 patients exhibited histological gastritis and were H. pylori positive as assessed by histology, culture and urease test. Twelve of these 18 patients received 240 mg twice daily colloidal bismuth subcitrate for four weeks before re-endoscopy. Gastric biopsies from H. pylori positive patients were incubated under basal and Ca(2+)-ionophore mediated conditions: Radioimmunoassay analysis of the supernatant showed basal release of prostaglandin E2 and leukotriene C4 was slightly but not significantly elevated in H. pylori positive mucosa. However in H. pylori positive mucosa there was an 85% increase in leukotriene C4 synthesis when biopsies were incubated with ionophore, compared to only 13% increase in H. pylori negative mucosa (p less than 0.02). After eradication of H. pylori by colloidal bismuth subcitrate, there was a clearance of inflammatory cell infiltrate as assessed by histology and a significant reduction in ionophore-mediated leukotriene C4 formation compared with before treatment (p less than 0.02). These results suggest that H. pylori gastritis is associated with increased capacity to generate leukotriene C4, which may amplify the damaging effects of the bacteria on gastric mucosa.
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PMID:Eicosanoid synthesis and Helicobacter pylori associated gastritis: increase in leukotriene C4 generation associated with H. pylori colonization. 164 5

The urease extracted from 6 strains of Helicobacter pylori (HP) was used as antigen to detect sera anti-urease antibodies of HP in 136 patients with gastric diseases and 13 persons with normal gastric mucosa by enzyme-linked immunosorbent assay (ELISA). The antigen proved to be pure and specific for ELISA. For a titre of 450EU or over 450EU the test had a sensitivity of 91.96% and a specificity of 86.49%. The results of the ELISA showed excellent correlation with microbiological detection of HP and histological examination of the antrum. The level of sera antibody showed a relation to the bacterial amount of HP in gastric mucosa, but no connection with the severity of gastritis. While ELISA may be effective for the serodiagnosis of HP infection and is able to distinguish patients with normal antrum mucosa from those with gastritis. The test does not help to distinguish those with antrum gastritis from those with peptic ulcer. It also provides a reliable method for epidemiological investigation of HP infection.
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PMID:[ELISA for detection of anti-urease antibodies of Campylobacter pylori and its application]. 166 Jul 62


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