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 mechanism by which Helicobacter pylori (Hp) predisposes to duodenal and gastric ulcers remains still unclear. It is possible that Hp infection impaires gastric secretion. Evaluation of gastric acid and mucus secretion before and after Hp eradication would let to estimate the influence of Hp infection on gastric secretion. To evaluate the effect of Hp infection on gastric acid and gastric mucous secretion before and one year after Hp eradication. We examined 28 Hp positive peptic ulcer disease patients (10-gastric ulcer GU, 18-duodenal ulcer DU) before and one year after antibacterial treatment. Gastric acid output was examined basely (BAO) and in response to pentagastrin (6 micrograms/kg) (MAO) using Kay's standard method. Some components of gastric mucus as fucose, galactose, hexosamines and sialic acid were measured using calorimetric methods basaly and after pentagastrin stimulation. Plasma gastrin concentration was measured in 20 patients (6-GU, 14-DU) by radioimmunoassay before and one year after eradication. Hp status was determined by rapid urease test (CLO) and histology (Giemsa stain). One year after Hp successful eradication gastric acid secretion was significantly reduced-BAO: 3,31 vs 1,474 mmol/h; MAO: 19,63 vs 14,85 mmol/h, p < 0.05. Plasma gastrin concentration decreased significantly from 9,783 to 6,017 pmol/I, p < 0.05. In patients with ineffective eradication we did not observe any significant changes in gastric acid secretion. An evident, but not statistically significant, decrease of sialic acid output in eradicated patients was noted. The study has shown the significant influence of Hp infection on gastric acid secretion. Those results support the hypothesis that increased gastric acid secretion may be one of the pathogenic mechanism of Hp infection inducing mucosal damage.
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PMID:Helicobacter pylori infection and gastric secretion in duodenal and gastric ulcer patients--the effect of eradication after one year. 937 18

The cause of gastric cell injury induced by Helicobacter pylori was investigated in vitro using gastric mucosal cells derived from male Japanese white rabbits. To evaluate the contribution of the potent urease activity of H. pylori to gastric mucosal cell injury, the supernatant of the H. pylori bacterial pellet, solubilized with N-octyl-glucoside, was added to the gastric mucosal cell suspension. Cell injury was assessed by lactate dehydrogenase (LDH) release into the extracellular fluid. Treatment of cells with H. pylori extracts together with urea resulted in high levels of LDH release, suggesting definite gastric mucosal cell injury, and elevation of ammonia concentration was also observed. In contrast, incubation with H. pylori extracts alone or urea solution alone did not result in increased LDH release or elevated ammonia concentrations. The degree of LDH release from gastric mucosal cells due to H. pylori extracts in the presence of urea was similar to that induced by administration of the same amount of exogenous ammonia. The addition of acetohydroxamic acid, a potent specific urease inhibitor, remarkably inhibited ammonia production, the elevation of pH of extracellular fluid, and LDH release in a dose-dependent manner. These results suggest that ammonia produced by potent urease activity of H. pylori in the presence of urea plays an important role in the pathogenesis of gastric mucosal cell injury.
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PMID:Studies on gastric mucosal cell injury induced by Helicobacter pylori. 947 43

This study compared specific phenotypic and potential virulence characteristics of Staphylococcus aureus isolates from invasive infections and nasal carriers. Three hundred and sixty isolates were studied; 154 from septicaemia (69 line associated, 85 non-line), 79 from continuous ambulatory peritoneal dialysis (CAPD) peritonitis, 64 from bone/joint infections and 64 from healthy nasal carriers. The isolates were tested for production of enterotoxins (SE) A, B, C or E, toxic shock syndrome toxin-1 (TSST-1) protein A, and also for lipolytic, proteolytic, fibrinolytic and haemolytic activities. In addition phage typing, crystal violet reaction, urease and galactose breakdown were studied. Seventy-one percent of isolates were enterotoxigenic. Production of SEA was significantly lower amongst the bone/joint isolates. Production of SEB, was lower among the control group compared with CAPD, bone/joint, and non-line septicaemia isolates. SEE production was higher among the bone/joint isolates compared with the CAPD and non-line septicaemias and production of TSST-1 was significantly higher among nasal isolates compared with isolates causing infection. Almost all of the isolates were lipolytic, with highest activity amongst nasal and bone/joint isolates. Fibrinolytic activity was similar in the five groups of isolates. Proteolytic activity ranged from 35 to 62% of isolates with the lowest frequency among septicaemia isolates. In all, 80-90% of isolates were haemolytic, although CAPD isolates were less likely to be haemolytic. Isolates from the control and CAPD group more frequently belonged to phage group I. TSST-1 does not appear to be an important requirement for invasive infections, but SEB may be. Proteolysis and intensity of lipolysis appear to be less important in septicaemia, and haemolysis may not be important in CAPD peritonitis.
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PMID:Comparative phenotypic characteristics of Staphylococcus aureus isolates from line and non-line associated septicaemia, CAPD peritonitis, bone/joint infections and healthy nasal carriers. 951 32

To investigate urease-independent mechanisms by which Helicobacter pylori resists acid stress, subtractive RNA hybridization was used to identify H. pylori genes whose expression is induced after exposure to acid pH. This approach led to the isolation of a gene that encoded a predicted 34.8kDa protein (WbcJ), which was homologous to known bacterial O-antigen biosynthesis proteins involved in the conversion of GDP-mannose to GDP-fucose. An isogenic wbcJ null mutant strain failed to express O-antigen and Lewis X or Lewis Y determinants and was more sensitive to acid stress than was the wild-type strain. Qualitative differences in LPS profiles were observed in H. pylori cells grown at pH 5 compared with pH 7, which suggests that H. pylori may alter its LPS structure in response to acidic pH. This may be an important adaptation facilitating H. pylori colonization of the acidic gastric environment.
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PMID:Acid-induced expression of an LPS-associated gene in Helicobacter pylori. 978 82

Little is known about bacteria associated with asymptomatic bacteriuria (ABU) with regard to urinary tract colonization mechanisms. In this study, virulence properties of Escherichia coli 83972, a strain that was isolated from a clinical ABU episode, were examined. The genetic potential for expression of P and type 1 pili was demonstrated, and DNA sequences related to type 1C and G (UCA) pilus genes were also detected. However, E. coli 83972 did not express D-mannose-resistant or D-mannose-sensitive hemagglutination after growth under standard conditions in vitro or upon isolation from the urine of colonized test subjects. Limited uroepithelial cell adherence was observed in vivo, and weak D-mannose-sensitive hemagglutination was detected after extended growth in urine in vitro.
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PMID:Virulence properties of Escherichia coli 83972, a prototype strain associated with asymptomatic bacteriuria. 986 49

Phenotypic and phylogenetic studies were performed with two strains (OCh 317T and OCh 318; T = type strain) of aerobic chemoheterotrophic bacteriochlorophyll-containing bacteria isolated from water of a saline lake located on the west coast of Australia. Both strains were Gram-negative, short rods and were motile by means of polar flagella. Catalase, oxidase, nitrate reductase, phosphatase and urease were produced. The cells utilized D-glucose, citrate, glycolate, pyruvate and ethanol. Acids were produced from L-arabinose, D-fructose, D-galactose, D-glucose, D-ribose and D-xylose. The strains could grow in media containing 0.5-7.5% NaCl. Bacteriochlorophyll a was synthesized under aerobic conditions. The results of 16S rRNA gene sequence comparisons revealed that strain OCh 317T represented a new lineage in the alpha-3 group of the class Proteobacteria. Strains OCh 317T and OCh 318 were identified as strains of the same species because of their very similar phenotypic characteristics and their previously described high DNA-DNA homology. Therefore, it was concluded that the two strains should be assigned to a new genus and species, for which the name Rubrimonas cliftonensis is proposed. The type strain is OCh 317T (= JCM 10189T).
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PMID:Rubrimonas cliftonensis gen. nov., sp. nov., an aerobic bacteriochlorophyll-containing bacterium isolated from a saline lake. 1002 64

Strain 130ZT was isolated from the bovine rumen. It is a facultatively anaerobic, pleomorphic, Gram-negative rod. It exhibits a 'Morse code' form of morphology, which is characteristic of the genus Actinobacillus. Strain 130ZT is a capnophilic, osmotolerant succinogen that utilizes a broad range of sugars. It accumulates high concentrations of succinic acid (> 70 g l-1). Strain 130ZT is positive for catalase, oxidase, alkaline phosphatase and beta-galactosidase, but does not produce indole or urease. Acid but no gas is produced from D-glucose and D-fructose. 16S rRNA sequence analysis places strain 130ZT within the family Pasteurellaceae; the most closely related members of the family Pasteurellaceae have 16S rRNA similarities of 95.5% or less with strain 130ZT. Strain 130ZT was compared with Actinobacillus lignieresii and the related Bisgaard Taxa 6 and 10. Based upon morphological and biochemical properties, strain 130ZT is most similar to members of the genus Actinobacillus within the family Pasteurellaceae. It is proposed that strain 130ZT be classified as a new species, Actinobacillus succinogenes. The type strain of Actinobacillus succinogenes sp. nov. is ATCC 55618T.
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PMID:Actinobacillus succinogenes sp. nov., a novel succinic-acid-producing strain from the bovine rumen. 1002 65

Phenotypic and phylogenetic studies were performed with two strains (OCh 239T and OCh 210T, T = type strain) of aerobic bacteriochlorophyll-containing bacteria isolated from the charophytes and the epiphytes on the stromatolites, respectively, of a saline lake located on the west coast of Australia. Both strains were chemoheterotrophic, Gram-negative and motile rods with subpolar flagella. Catalase and oxidase were produced. ONPG reaction was positive. Cells utilized D-glucose, acetate, butyrate, citrate, DL-lactate, DL-malate, pyruvate, succinate, L-aspartate and L-glutamate. Acids were produced from D-fructose and D-glucose. Bacteriochlorophyll a was synthesized under aerobic conditions. Strain OCh 239T had nitrate reductase and phosphatase. Acids were produced from L-arabinose, D-galactose, lactose, maltose, D-ribose and sucrose. The strain could grow in 0-20.0% (w/v) NaCl. Strain OCh 210T had urease. Hydrolysis of gelatin was positive. Acids were produced from D-xylose. The strain could grow in 0.5-20.0% (w/v) NaCl. The results of 16S rRNA sequence comparisons revealed that strains OCh 239T and OCh 210T formed a new cluster within the alpha-3 group of the alpha subclass of the class Proteobacteria. The similarity value of the 16S rRNA sequences between strains OCh 239T and OCh 210T was 95.8%. Therefore, it was concluded that these two strains should be placed in a new genus, Roseivivax gen. nov., as the new species Roseivivax halodurans sp. nov. and Roseivivax halotolerans sp. nov. The type species of the genus is Roseivivax halodurans. The type strains of Roseivivax halodurans and Roseivivax halotolerans are OCh 239T (= JCM 10272T) and OCh 210T (= JCM 10271T), respectively.
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PMID:Roseivivax halodurans gen. nov., sp. nov. and Roseivivax halotolerans sp. nov., aerobic bacteriochlorophyll-containing bacteria isolated from a saline lake. 1031 85

Conventional biochemical tests were compared with reactions in a multiple test system, MicroScan Walkaway (Dade Diagnostic Inc. MicroScan Divison, West Sacramento, California) in conjugation with the Combo Pos ID Panels (Dade Diagnostic Inc. MicroScan Divison, West Sacramento, California), in order to evaluate the accuracy for the identification of 99 clinical isolates of Staphylococcus spp. and five reference strains. False-negative or positive reactions were detected from Voges-Proskauer, urease and mannose tests. A good correlation was found among the two identification systems for the fermentation of trehalose, lactose, raffinose, as well as for arginine dyhydrolase, esculin hydrolisis and nitrate reduction. From the results of the present study, it is concluded that the MicroScan Walkaway system is a reliable method for identification of staphylococci (94.23%), although 8.2% could be identified to the species level only after use of additional test.
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PMID:Evaluation of the MicroScan system for identification of staphylococci. 1062 74

The urease genes of Streptococcus salivarius 57.1 are tightly repressed in cells growing at neutral pH. When cells are cultivated at acidic pH values, the urease genes become derepressed and transcription is enhanced when cells are growing under carbohydrate-excess conditions. Previously, the authors proposed that the bacterial sugar:phosphotransferase system (PTS) modulated the DNA-binding activity by phosphorylation of the urease repressor when carbohydrate was limiting. The purpose of this study was to assess whether enzyme I (EI) of the PTS could be involved in modulating urease expression in response to carbohydrate availability. An EI-deficient strain (ptsI18-3) of S. salivarius 57.1 was constructed by insertional inactivation of the ptsI gene. The mutant had no measurable PTS activity and lacked EI, as assessed by Western analysis. The mutant grew as well as the wild-type strain on the non-PTS sugar lactose, and grew better than the parent when another non-PTS sugar, galactose, was the sole carbohydrate. The mutant was able to grow with glucose as the sole carbohydrate, but displayed a 24 h lag time and had a generation time some threefold longer than strain 57.1. The mean OD600 attained after 48 h by ptsI18-3 supplied with fructose was 0.16, with no additional growth observed even after 3 d. Urease expression in the wild-type and mutant strains was assessed in continuous chemostat culture. Repression of urease at neutral pH was seen in both strains under all conditions tested. Growth of wild-type cells on limiting concentrations of lactose resulted in very low levels of urease expression compared with growth on PTS sugars. In contrast, under similar conditions, urease expression in ptsI18-3 was restored to levels seen in the parent growing on PTS sugars. Growth under conditions of lactose excess resulted in further derepression of urease, but ptsI18-3 expressed about threefold higher urease activity than 57.1. The results support a role for EI in urease regulation, but also indicate that additional factors may be important in regulating urease gene expression.
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PMID:Inactivation of the ptsI gene encoding enzyme I of the sugar phosphotransferase system of Streptococcus salivarius: effects on growth and urease expression. 1083 46


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