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)

Light and electron microscopic and microbiologic evaluations were performed on mucosa of stomachs from 120 healthy slaughtered pigs. Helicobacter pylori was not found, but a tightly spiralled bacterium, not previously described, was seen in histological sections and/or in carbol fuchsin stained smears in 13 (10.8%) stomachs. In paraffin sections stained with carbol fuchsin, the bacteria were seen in the mucus of the lumen of the antral pits and in the mucosa surface within and beneath the mucus. In this sections of Polilyte embedded tissue the bacteria had three to eight spiral turns per cell (mean = five), flattened ends, a Gram-negative cell-wall structure and a sheathed flagella. The urease test was positive in gastric mucosa of 13 bacteria-positive pigs (10.8%). The microorganism was not cultured and did not cross-react with polyclonal antibodies raised in rabbits against H. pylori. Superficial chronic gastritis and "borderline" gastritis were observed in antral mucosa of 10 (76.9%) and of two (15.4%) spiral bacteria-positive pigs, respectively.
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PMID:A spiral microorganism in the stomach of pigs. 170 May 35

Antral biopsies were obtained by gastrointestinal endoscopy on 143 adult patients with dyspeptic symptoms of gastritis or peptic ulcer disease. A direct Gram stain and a direct urease test were performed on each biopsy in addition to culture. Forty-three biopsies (30%) were considered positive for Helicobacter pylori based on culture or histologic examination, or both. Thirty-one biopsies (72% sensitivity) were positive for both direct tests, whereas 95 of 100 negative cultures were negative for both tests. Thirty-eight of the 43 positive biopsies were Gram stain positive (sensitivity, 88%; specificity, 100%). The direct urease test alone was positive at 4 hr for 29 biopsies (sensitivity, 67%; specificity, 100%) and at 24 hr for 38 biopsies (sensitivity, 74%; specificity, 95%). Rapid presumptive diagnosis of H. pylori in antral biopsies was obtained when at least one direct test, Gram stain or urease, was positive.
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PMID:Direct gram stain and urease test to detect Helicobacter pylori. 170 38

We present the results of ultrastructural studies of gastric mucosa obtained through upper digestive endoscopy of eight patients with suspicious symptoms of non ulcer dyspepsia or peptic ulcer. Two were male and six female with a median age of 54 years. The urease test to determine the presence of HP and Hematoxylin-Eosin and Warthin-Starry staining techniques were practiced with the purpose of a better detection of bacteria and gastritis. We did not find any correlation between the endoscopic results and the presence of gastritis or HP. Of the 8 patients only one had negative results for HP and for Electron microscopy studies. Chronic active gastritis was seen with light microscopy in all of the cases. Three in this group presented mild focal dysplasia and one case intestinal metaplasia type IIa. The main ultrastructural findings were: a) diminished or absent microvilli underneath the bacteria; b) HP inside phagolysosomes in the cytoplasm of the epithelial cells; c) in some cases, the bacteria was attached to the cell membrane; d) the cellular wall of HP contains mucopolysaccharides and up to four polar flagella; e) there are polymorphonuclear leucocytes in the epithelium. We conclude that Electron Microscopy is not a routine method for studying HP, but it constitutes a good method to study pathogenicity of the bacteria.
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PMID:[Ultrastructural study of the antral mucosa to determine the presence of Helicobacter pylori and its association with chronic active gastritis]. 172 15

The mechanism by which Helicobacter pylori, a noninvasive bacterium, initiates chronic antral gastritis in humans is unknown. We now show that H. pylori releases products with chemotactic activity for monocytes and neutrophils. This chemotactic activity was inhibited by antisera to either H. pylori whole bacteria or H. pylori-derived urease. Moreover, surface proteins extracted from H. pylori and purified H. pylori urease (a major component of the surface proteins) exhibited dose-dependent, antibody-inhibitable chemotactic activity. In addition, a synthetic 20-amino acid peptide from the NH2-terminal portion of the 61-kD subunit, but not the 30-kD subunit, of urease exhibited chemotactic activity for monocytes and neutrophils, localizing the chemotactic activity, at least in part, to the NH2 terminus of the 61-kD subunit of urease. The ability of leukocytes to chemotax to H. pylori surface proteins despite formyl-methionyl-leucyl-phenylalanine (FMLP) receptor saturation, selective inhibition of FMLP-mediated chemotaxis, or preincubation of the surface proteins with antiserum to FMLP indicated that the chemotaxis was not FMLP mediated. Finally, we identified H. pylori surface proteins and urease in the lamina propria of gastric antra from patients with H. pylori-associated gastritis but not from uninfected subjects. These findings suggest that H. pylori gastritis is initiated by mucosal absorption of urease, which expresses chemotactic activity for leukocytes by a mechanism not involving N-formylated oligopeptides.
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PMID:Surface proteins from Helicobacter pylori exhibit chemotactic activity for human leukocytes and are present in gastric mucosa. 173 14

We evaluated a commercially available second-generation anti-H. pylori immunoglobulin G enzyme immunoassay (EIA) (Cobas Core Anti-Helicobacter pylori EIA; Roche S. A., Basel, Switzerland) for serodiagnosis of H. pylori infection. The results of the assay were assessed in relation to the results of bacterial culture, urease testing, and histological Giemsa stain of gastric biopsy specimens from 1,134 patients with a variety of symptoms relating to the upper gastrointestinal tract. H. pylori was detected in biopsy specimens from 660 (58.2%) patients: 6 had a normal mucosa, 123 had chronic gastritis only, and 531 were found to have chronic active gastritis by histology; endoscopy showed duodenal and gastric ulcers in 137 and 64 patients of the last two groups, respectively. The test was evaluated with different age and ethnic groups. The prevalence, sensitivity, specificity, and positive and negative predictive values were, respectively, (i) for Belgian patients between 18 and 40 years old, 34, 93, 95, 91, and 96%; (ii) for Belgian patients more than 40 years old, 53, 96, 91, 93, and 95%; and (iii) the Mediterranean patients more than 17 years old, 87, 94, 70, 95, and 64%. All sera showing discordant immunoassay results compared with the results of histology and culture of biopsy specimens, as well as those with borderline immunoassay results, were tested further by immunoblotting. Among the EIA results considered false negative, we demonstrated an absence of seroconversion in 14 of 19 patients tested by immunoblotting. Among the EIA results considered false positive, immunoblotting showed the presence of specific antibodies in 28 of 37 patients tested. Among the borderline results obtained in the first assay with 22 patients' sera, a second assay showed positive results in 10 patients (8 were positive by immunoblotting) and negative reactions in 10 patients (9 were negative by immunoblotting), whereas 2 remained borderline. These data indicate that sera showing borderline immunoassay results must be tested again. In conclusion, this commercially available second-generation EIA, which is easy and quick to perform, was found highly reliable for the serodiagnosis of H. pylori infection.
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PMID:Evaluation of a commercially available second-generation immunoglobulin G enzyme immunoassay for detection of Helicobacter pylori infection. 173 50

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 strain 85P using a shuttle cosmind 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 the 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. This fragment was selectively amplified by polymerase chain reaction (P.C.R.) using two primers designed to target the urease region of all H. pylori isolates present in biological specimen. In addition, P.C.R. followed by direct DNA sequencing of the 294-bp amplified product was shown to be useful to identify and to distinguish between different H. pylori isolates.
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PMID:[Development of genetic and molecular approaches for the diagnosis and study of the pathogenicity of Helicobacter pylori, agent of gastric inflammatory diseases]. 174 19

Helicobacter (Campylobacter) pylori is strongly associated with type B gastritis. The detection of H. pylori, which entails histological examination and culture of gastric biopsy specimens, takes several days. There has been much interest in developing more rapid tests, including non-invasive ones. Using histology and/or culture as the 'gold standard', several methods to detect H. pylori were compared and evaluated. The organism was detected in 84 of 100 consecutive patients attending the Gastrointestinal Unit of King Edward VIII Hospital for upper gastrointestinal tract endoscopy. Histological examination was the most sensitive (98%) and specific (100%) method used in detecting H. pylori in gastric biopsy specimens. An enzyme-linked immunosorbent assay to detect specific IgG antibodies to whole H. pylori organisms is a moderately sensitive (82%), non-invasive method but it is nonspecific (38%). Although culture was specific (100%), it was less sensitive (68%) than histological examination. The 'conventional' urease assays must be performed under controlled conditions (37 degrees C) for optimal results (sensitivity, 71%).
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PMID:Evaluation of various laboratory techniques to diagnose Helicobacter pylori in patients with upper gastro-intestinal tract symptoms. 174 46

Helicobacter pylori has been implicated in the genesis of human gastritis, dyspepsia, and peptic ulcers. However, its influence in the quality of experimental gastric ulcer healing has not been previously investigated. Standardized gastric fundic ulcers were produced in 50 male Sprague-Dawley rats (150-200 g) by a 4 mm in diameter focal, serosal application of 100% acetic acid. Thirty rats were administered 2 ml H. pylori suspension (urease producing, ATCC 43504) in normal saline (10(8) CFU/ml) 2x/day for 7 days. Twenty rats (controls) received 2 ml normal saline 2x/day for 7 days. Gastric ulcer surface area was measured under a dissecting microscope and mucosal specimens were obtained for qualitative and quantitative histology. No gross or microscopic duodenal abnormalities were identified at sacrifice. Ninety percent of control rats showed grossly and microscopically entirely healed ulcers. The remaining 10% showed partially reepithelialized ulcers (area, 0.78 to 1.77 mm2; mean, 1.27 +/- 0.7 mm2). The grossly "healed" mucosa demonstrated marked dilatation of gastric glands lined with mature surface epithelial cells. Parietal cells were scanty (5-10% of all cells). One hundred percent of the H. pylori-exposed rats showed persistence of chronic active ulcers (area, 1.76 to 19.63 mm2; mean, 8.95 +/- 6.15 mm2). The ulcer beds were infiltrated by acute and chronic inflammatory cells, abundant fibroblasts, and capillary networks. The raised ulcer borders were characterized by dilated glands lined by mature surface epithelial cells. Various special stains demonstrated the presence of H. pylori in the surface mucus and within the crypts.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Helicobacter pylori affects the quality of experimental gastric ulcer healing in a new animal model. 174 15

Eradication of Helicobacter pylori is associated with a fall in serum gastrin but the way in which the infection raises the serum gastrin concentration is not clear. It may be related to the ammonia produced by the bacterium's urease stimulating gastrin release by the antral G cells. Alternatively, the antral gastritis induced by the infection may modify the regulation of gastrin release. We have examined serum gastrin in 10 patients before and 24 hours after starting triple anti-H pylori treatment consisting of tripotassium dicitrato bismuthate 120 mg four times daily, metronidazole 400 mg three times daily, and amoxycillin 500 mg three times daily. The urease activity, assessed by the 20 minute value of the 14C-urea breath test, fell from a median of 176 (range 116-504) kg% dose/mmol CO2 x 100 pretreatment to 5 (2-15) at 24 hours (p less than 0.005). The median antral gastritis score was 6 (4-6) pretreatment and fell to 3 (2-5) at 24 hours (p less than 0.02), and this was due to resolution of the polymorphonuclear component. Despite this complete suppression of bacterial urease activity and partial resolution of antral gastritis the median basal gastrin concentration remained unchanged, being 57 ng/l (45-77) pretreatment and 59 ng/l (45-80) at 24 hours and the median integrated gastrin response to a standardised meal was also unaltered, being 4265 ng/l/min (range 1975-8350) and 4272 ng/l/min (range 2075-6495) respectively. These findings do not support a causal association between H pylori urease activity and hypergastrinaemia and show rapid improvement of antral gastritis after starting anti-H pylori treatment.
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PMID:Is Helicobacter pylori associated hypergastrinaemia due to the bacterium's urease activity or the antral gastritis? 175 56

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.
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PMID:[The pathogenesis of stomach and duodenal involvement in chronic opisthorchiasis. 1. The urease test]. 175 56


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