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)

On the basis of biochemical, phenotypic, and 16S rRNA analysis, a novel gram-negative bacterium, isolated from normal and diarrheic dogs as well as humans with gastroenteritis, has been recently named Helicobacter canis. A 2-month-old female crossbred puppy was submitted to necropsy with a history of weakness and vomiting for several hours prior to death. The liver had multiple and slightly irregular yellowish foci up to 1.5 cm in diameter. Histologically, the liver parenchyma contained randomly distributed, occasionally coalescing hepatocellular necrosis, often accompanied by large numbers of mononuclear cells and neutrophils. Sections of liver stained by the Warthin-Starry silver impregnation technique revealed spiral- to curve-shaped bacteria predominantly located in bile canaliculi and occasionally in bile ducts. Aerobic culture of liver was negative, whereas small colonies were noted on Campylobacter selective media after 5 days of microaerobic incubation. The bacteria were gram negative and oxidase positive but catalase, urease, and indoxyl acetate negative; nitrate was not reduced to nitrite, and the organism did not hydrolyze hippurate. The bacteria were also resistant to 1.5% bile. Electron microscopy revealed spiral-shaped bacteria with bipolar sheathed flagella. By 16S rRNA analysis, the organism was determined to be H. canis. This is the first observation of H. canis in active hepatitis in a dog and correlates with recent findings of Helicobacter hepaticus- and Helicobacter bilis-related hepatic disease in mice. Further studies are clearly warranted to ascertain whether H. canis-associated hepatitis is more widespread in canines as well as a cause of previously classified idiopathic liver disease in humans.
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PMID:Helicobacter canis isolated from a dog liver with multifocal necrotizing hepatitis. 888 May 4

We have devised a procedure that permits the cultivation of a gram-positive coccoid species from biopsy material obtained from the antrum of the stomachs of patients with gastric disorders. Antibodies directed against surface proteins obtained from the coccoid isolates were detected in all patients with gastric disorders examined in this study, including both Helicobacter pylori-infected and H. pylori-uninfected patients. Several of these isolates, including a prototype designated strain SL100, have been characterized in some detail. Strain SL100 exhibits urease and exceptionally high catalase activities and assumes a variety of spherical morphologies as detected by electron microscopy. This isolate expresses an adhesin that binds to gastric mucin. The adhesin activity was detected only after the isolate was exposed to an acidic pH, suggesting that in the natural process of infection, the low pH of the stomach unmasks a cell surface component with adhesin activity. Strain SL100 grows best under a microaerophilic conditions (10% CO2, 5% O2, 85% N2), but it also grows quite well under aerobic conditions. Thus, this organism would be expected to proliferate outside of the human host as well as in the gastric mucosa. Oral infection of newborn piglets resulted in colonization of the gastric antrum and growth retardation. Preliminary taxonomic classification indicates similarity to the Staphylococcus DNA homology groups containing S. cohnii and S. xylosus. One of us (C.K.) apparently became infected with this organism as indicated by gastric symptoms and the subsequent presence of strain-specific antisera not present in other workers in the laboratory.
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PMID:Successful cultivation of a potentially pathogenic coccoid organism with trophism for gastric mucin. 897 91

Helicobacter pylori colonises the gastric mucosa of humans and causes both antral gastritis and duodenal ulcer disease. Exactly how H. pylori causes disease is not known but several pathogenic determinants have been proposed for the organism. These include adhesins, cytotoxins and a range of different enzymes including urease, catalase and superoxide dismutase. Surface molecules of H. pylori such as flagella, lipopolysaccharide, the urease enzyme and outer membrane proteins are putative adhesin molecules. While phosphatidylethanolamine and the Lewis(b) blood group antigen have been proposed as receptor molecules for the organism the exact mechanism by which H. pylori adheres to the gastric mucosa has still to be identified. Characterisation of the adhesins of H. pylori could lead to the development of adhesin analogues for use in the inhibition of colonisation and improved therapy for ulcer disease. In vivo studies with isogenic mutants which are incapable of adhering to the gastric mucosa would greatly clarify the significance of adherence. Such mutants could possibly be useful as a vaccine against infection with wild-type organisms.
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PMID:Cell envelope characteristics of Helicobacter pylori: their role in adherence to mucosal surfaces and virulence. 898 94

Phylogenetic analyses of 16S rRNA gene sequences by distance matrix and parsimony methods indicated that six strains of bacteria isolated from deep saturated Atlantic coastal plain sediments were closely related to the genus Sphingomonas. Five of the strains clustered with, but were distinct from, Sphingomonas capsulata, whereas the sixth strain was most closely related to Blastobacter natatorius. The five strains that clustered with S. capsulata, all of which could degrade aromatic compounds, were gram-negative, non-spore-forming, non-motile, rod-shaped organisms that produced small, yellow colonies on complex media. Their G + C contents ranged from 60.0 to 65.4 mol%, and the predominant isoprenoid quinone was ubiquinone Q-10. All of the strains were aerobic and catalase positive. Indole, urease, and arginine dihydrolase were not produced. Gelatin was not liquified, and glucose was not fermented. Sphingolipids were present in all strains; 2OH14:0 was the major hydroxy fatty acid, and 18:1 was a major constituent of cellular lipids. Acid was produced oxidatively from pentoses, hexoses, and disaccharides, but not from polyalcohols and indole. All of these characteristics indicate that the five aromatic-degrading strains should be placed in the genus Sphingomonas as currently defined. Phylogenetic analysis of 16S rRNA gene sequences, DNA-DNA reassociation values, BOX-PCR genomic fingerprinting, differences in cellular lipid composition, and differences in physiological traits all indicated that the five strains represent three previously undescribed Sphingomonas species. Therefore, we propose the following new species: Sphingomonas aromaticivorans (type strain, SMCC F199), Sphingomonas subterranea (type strain, SMCC B0478), and Sphingomonas stygia (type strain, SMCC B0712).
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PMID:Taxonomic study of aromatic-degrading bacteria from deep-terrestrial-subsurface sediments and description of Sphingomonas aromaticivorans sp. nov., Sphingomonas subterranea sp. nov., and Sphingomonas stygia sp. nov. 899 22

Forty-four strains of a phenotypically unique Campylobacter were isolated from the faeces of 26 of 45 cows in a single herd. Isolation involved enrichment and membrane filtration onto blood agar or plating onto cefoperazone amphotericin teicoplanin agar. The strains exhibited phenotypic characteristics typical for Campylobacter species. However, they were unusual in that they produced urease and copious H2S in triple sugar iron (TSI) medium, but did not produce catalase. They did not grow aerobically. None of the strains grew on modified cefoperazone charcoal deoxycholate agar (mCCDA). Macrorestriction profiles of chromosomal DNA were prepared for 15 strains using pulsed-field gel electrophoresis (PFGE). Twelve of 15 profiles were identical and all appeared to be closely related. These catalase-negative, urease-positive campylobacters (CNUPC) represent a group not previously reported. Their sensitivity to antibiotics normally used in selective media for campylobacters might explain why they have not previously been encountered. Their ecological significance and importance with respect to human and animal disease remain to be assessed.
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PMID:Isolation and characterization of a novel catalase-negative, urease-positive Campylobacter from cattle faeces. 902 6

The recent isolation of Helicobacter pylori from cats obtained from a commercial supplier has potentially important public health implications. The present study investigated whether H. pylori infection was common in stray cats. Twenty-five cats were examined for the presence of H. pylori by histological examination, culture and two polymerase chain reaction (PCR) assays. Histologically, the gastric biopsy specimens from all cats showed large spiral organisms typical of H. felis and not H. pylori. Samples from 23 cats yielded bacterial growth and two had no growth. Colonies grossly similar to H. pylori were tested for catalase, oxidase, urease and Gram's stain reactions. None was H. pylori. All samples tested as positive by the Helicobacter 16S rRNA genus-specific PCR assay and only six cats and a mouse stomach infected with H. heilmannii gave positive results with the adhesin subunit A (hpaA)-specific PCR assay, which is consistent with either H. pylori or H. heilmannii. The helicobacters identified in these samples by PCR were not cultivable and hence were probably H. heilmannii. H. pylori infection is uncommon in stray cats and owning pet cats should not be a threat to public health in relation to H. pylori infection.
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PMID:Failure to isolate Helicobacter pylori from stray cats indicates that H. pylori in cats may be an anthroponosis--an animal infection with a human pathogen. 915 31

The mode of transmission of Helicobacter pylori is unknown. Since viable bacteria have been shown to be excreted in feces from infected individuals and houseflies habitually develop and feed on excrement, we hypothesized that flies ingest and harbor H. pylori and, in turn, contaminate the human environment. This study examined the possible vector potential of houseflies (Musca domestica) for H. pylori. Caged houseflies were exposed to freshly grown H. pylori on agar plates. After a 6-h feeding period, the plates were removed and were replaced with sterile petri dishes containing a droplet of sterile brucella broth. At regular intervals, small numbers of houseflies were removed for microbiological and histological analysis, and the petri dishes were replaced with fresh sterile plates with fresh drops of brucella broth. The flies' bodies, the flies' dissected alimentary tracts, and excreta on the petri dishes were cultured for H. pylori, whose identity was confirmed by the urease, catalase, and oxidase reactions and Gram staining. In contrast to control flies, viable H. pylori could be isolated from external surfaces for up to 12 h and from gut and excreta for as long as 30 h after the initial feeding period. After 30 h other gram-negative bacteria overgrew the cultures of samples from all locations tested, rendering the selective culture of H. pylori colonies impossible. Histological analysis revealed Helicobacter-like organisms in the gut lumen and attached to intestinal epithelial cells. We conclude that houseflies can harbor viable H. pylori on their bodies and in their intestinal tracts. They are also able to disseminate viable H. pylori in excreta, and they may therefore present a significant reservoir and be a vector in the transmission of H. pylori.
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PMID:Vector potential of houseflies (Musca domestica) for Helicobacter pylori. 916 33

A spiral-shaped bacterium with bipolar, single, nonsheathed flagella was isolated from the intestines of laboratory mice. The organism grew at 37 and 42 degrees C under microaerobic and anaerobic conditions, did not hydrolyze urea, was weakly positive for catalase and oxidase, reduced nitrate to nitrite, did not hydrolyze indoxyl acetate or hippurate, and was resistant to cephalothin and nalidixic acid. This is the first urease-negative, murine Helicobacter spp. isolated from intestines. Also, Helicobacter pullorum and this bacterium are unique among the genus Helicobacter in having nonsheathed flagella. The new bacterium appears to be part of the normal intestinal flora; although its pathogenic potential is unknown, this organism was also isolated from scid mice with diarrhea that were co-infected with Helicobacter bilis. On the basis of 16S rRNA gene sequence analysis data and biochemical and phenotypic criteria, the new organism is classified as a novel helicobacter, for which we propose the name Helicobacter rodentium. The type strain is MIT 95-1707 (= ATCC 700285).
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PMID:Helicobacter rodentium sp. nov., a urease-negative Helicobacter species isolated from laboratory mice. 922 92

The isolation of a new motile, gram-negative, heterotrophic, sulfur-reducing, microaerophilic, vibrioid bacterium, strain F1F6, from oxidized marine surface sediment (Arcachon Bay, French Atlantic coast) is described. Hydrogen (with acetate as the carbon source), formate (with acetate as the carbon source), pyruvate, lactate, alpha-ketoglutarate, glutarate, glutamate, and yeast extract supported growth with elemental sulfur under anaerobic conditions. Apart from H2 and formate, the oxidation of the substrates was incomplete. Microaerophilic growth was supported with hydrogen (acetate as the carbon source), formate (acetate as the carbon source), acetate, propionate, pyruvate, lactate, alpha-ketoglutarate, glutamate, yeast extract, fumarate, succinate, malate, citrate, and alanine. The isolate grew fermentatively with fumarate, succinate being the only organic product. Elemental sulfur and oxygen were the only electron acceptors used. Vitamins or amino acids were not required. The isolate was oxidase, catalase, and urease positive. Comparative 16S rDNA sequence analysis revealed a tight cluster consisting of the validly described species Sulfurospirillum deleyianum and the strains SES-3 and CCUG 13942 as the closest relatives of strain F1F6 (level of sequence similarity, 91.7 to 92.4%). Together with strain F1F6, these organisms form a novel lineage within the epsilon subclass of proteobacteria clearly separated from the described species of the genera Arcobacter, Campylobacter, Wolinella, and Helicobacter. Due to the phenotypic characteristics shared by strain F1F6 and S. deleyianum and considering their phylogenetic relationship, we propose the inclusion of strain F1F6 in the genus Sulfurospirillum, namely, as S. arcachonense sp. nov. Based on the results of this study, an emended description of the genus Sulfurospirillum is given.
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PMID:Sulfurospirillum arcachonense sp. nov., a new microaerophilic sulfur-reducing bacterium. 933 31

Although certain factors appear to predispose the host to infection by Helicobacter pylori, clearly the bacterium possesses a well-defined battery of virulence factors that allow the organism to: (1) colonize the gastric mucosa (urease, flagella, adhesins, acid-inhibitory protein, iron acquisition proteins, and heat shock proteins); (2) evade host defense (shedding of surface proteins, catalase, superoxide dismutase, and poorly reactive lipopolysaccharide); and (3) damage host tissue (vacuolating cytotoxin, protease, CagA-related factors, inducers of cytokines, and chemotaxins). Together these factors allow H. pylori to persist in the host, establishing a chronic infection. Although many of these virulence factors are produced by all strains of H. pylori, there are also well-defined pathogenicity islands (contiguous stretches of chromosomal DNA) present in some strains that encode additional proteins including CagA that potentiate virulence. Strains possessing these "virulence cassettes" are isolated more frequently from patients with the more serious clinical manifestations associated with duodenal ulcer than from patients with gastritis alone or nonulcer dyspepsia.
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PMID:Helicobacter pylori factors associated with disease development. 939 56


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