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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 identification of certain dermatophytes may be simplified by using biochemical tests such as urease, nutritional requirements (with commercially available media), and the in-vitro hair penetration test. No study that combines these tests in a diagnostic scheme for identification of the common dermatophytes has been published. one to 20 isolates each of 29 species of dermatophytes (one Epidermophyton floccosum, 10 Microsporum species, and 18 Trichophyton species) were used. They were grown on Christensen's urea agar and the seven nutritional media for the differentiation of the Trichophyton species; the in-vitro hair penetration test was performed in duplicate. Patterns were developed that have been tested and proven to be useful for more than 22 months. In addition, the Microsporum species were all grown on polished rice, and color and sporulation were recorded. All dermatophytes in this study were grown on either Mycosel agar or 2% malt extract agar, and on modified potato dextrose agar and modified Sabouraud agar. Macroscopic and microscopic examinations were made to determine qualitatively the amounts of growth and sporulation on each medium.
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PMID:Utilization of standard laboratory methods in the laboratory diagnosis of problem dermatophytes. 740 98

Lectins from the lichen Xanthoria parietina develop arginase activity. One of these lectins behaves as a secreted arginase whereas another is an endocellular enzyme. Both enzymes are glycosylated proteins differing in the occurrence of galactose instead of N-acetyl-D-glucosamine in secreted arginase. The affinity for the algal ligand (glycosylated cell wall urease) of secreted arginase is higher than that shown for the endocellular enzyme. When the lectin ligand is absent from the algal cell wall, both endocellular and secreted arginases seem to be able to enter algal cells. This uptake promotes the increase in the amount of algal putrescine, preferently as free polyamine, and the chloroplast is rapidly damaged. Induction of cell wall urease retains lectins outside the cells, on the cell wall, and chloroplast remains healthy.
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PMID:Correlationships between enzymatic activity of lectins, putrescine content and chloroplast damage in Xanthoria parietina phycobionts. 774 19

Methods for isolation of fecal 7 alpha-dehydroxylating bacteria are presented. A total of 219 strains were isolated from feces of healthy humans, and their ability to 7-dehydroxylate cholic, chenodeoxycholic, and ursodeoxycholic acids were examined. Of all the isolates, 14 strains were found to be capable of eliminating the hydroxy group at C-7 alpha and/or C-7 beta. All the isolates were strictly anaerobic, Gram-positive rods. Thirteen isolates were non-sporeforming bacteria showing certain saccharolytic properties with the production of acid and gas from dextrose, and were catalase-positive but indole-, lecithinase-, urease- and oxidase-negative. Based on the data available at present, it was concluded that they could be regarded as members of the genus Eubacterium. One strain, however was identified as Clostridium sordellii. The isolated strains capable of 7 alpha-dehydroxylating cholic acid and chenodeoxycholic acid were also able to oxidize the hydroxy group at C-7 alpha. Nine strains (10, 12, 36S, M-2, M-17, M-18, Y-98, Y-1112, and Y-1113) of the 7 alpha-dehydroxylating bacteria were confirmed to have 7 beta-dehydroxylation ability, but five strains (O-51, O-52, O-71, O-72, and Y-67) could not transform ursodeoxycholic acid to lithocholic acid.
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PMID:Isolation and characterization of bile acid 7-dehydroxylating bacteria from human feces. 778 73

The cause of gastric mucosal cell injury induced by Helicobacter pylori (H. pylori) was investigated in vitro using gastric mucosal cells derived from the stomach of male Japanese white rabbits. In order to evaluate the contribution of potent urease activity of H. pylori to gastric mucosal cell injury, supernatant of H. pylori bacterial pellet solubilized in a 1.0% solution of n-octyl-glucoside, the H. pylori extracts, was added to the rabbit gastric mucosal cell suspension. Cell injury was expressed by LDH release into the extracellular fluid of gastric mucosal cell suspension after 30 minutes incubation at 37 degrees C. Treatment of cells by H. pylori extracts (final concentration of 0.54 mg/ml) together with urea (final concentration at 50 mM) showed a high LDH release into the extracellular fluid suggesting definite gastric mucosal cell injury. Elevation of ammonia concentration and that of extracellular fluid pH were also observed by the treatment, whereas H. pylori extracts alone and urea solution alone did not. The ammonia concentration of extracellular fluid and LDH release were distinctly elevated in accord with increasing amount of H. pylori extracts under the existence of 50 mM urea. The degree of LDH release from gastric mucosal cell by H. pylori extracts under the existence of urea was similar to that induced by the administration of the same amount of exogenous ammonia. The addition of acetohydroxamic acid (AHA), a potent specific urease inhibitor, remarkably inhibited dose dependently the ammonia production, the elevation of pH of extracellular fluid and LDH release induced by H. pylori extracts under the presence of urea. These results suggest that the ammonia produced by potent urease activity of H. pylori under the presence of urea played 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]. 795 95

Twenty isolates of Pasteurella (Moraxella) anatipestifer from ducks with serositis and septicemia in Thailand between 1988 and 1989 were characterized by various tests. Eighteen isolates fermented glucose and maltose, 3 fructose and 1 each mannose, arabinose, trehalose or sorbitol. All isolates produced gelatinase but not urease, while 2, 3, 5 and 6 produced indole, were CAMP positive, and were proteolytic for milk and coagulated serum respectively. Seven enzymes, phosphatase alkaline, esterase (C4), esterase lipase (C8), leucine arylamidase, valine arylamidase, phosphatase acid and phosphoamidase were detected from all the isolates. The isolates were highly susceptible to ampicillin, erythromycin, penicillin G and tylosin. Gel-diffusion precipitin tests demonstrated that serotype 1 was most prevalent (60%) and serotype 6 followed (5%). Seven isolates (35%) were untypable. These results indicated that P. anatipestifer of serotype 1 played an important role in recent outbreaks of the disease in Thailand.
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PMID:Physiological characteristics, antimicrobial susceptibility and serotypes of Pasteurella anatipestifer isolated from ducks in Thailand. 820 23

A bacterial strain that was able to mineralize 2,4,6-trichlorophenol was isolated from a chlorophenol-fed percolator and was identified as a member of the genus Rhodococcus on the basis of chemotaxonomic characteristics and 16S RNA phylogenetic inference data. This organism (strain MBS1T [T = type strain]) exhibited a typical irregular rod-coccus cycle, and the cells had fimbria-like structures on their surfaces. The diagnostic cell wall amino acid was meso-diaminopimelic acid, and the sugars were arabinose and galactose; the mycolic acids contained 46 to 54 carbon atoms. The main menaquinone was MK-8(H2), and MK-9(H2) was a minor component. The cellular phospholipids were phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositolmannoside, phosphatidylglycerol, and diphosphatidylglycerol. Tuberculostearic acid was present. The whole-cell fatty acids were straight-chain acids with 14 to 18 C atoms. The G+C content of the DNA was 67.4 mol%. This organism grew on sucrose, pyruvate, and 2,4,6-trichlorophenol, and it oxidized a large number of carbon compounds, including catechol, 3-hydroxyphenylacetic acid, and phenol. It also exhibited beta-galactosidase, urease, and 2-acetyl-lactate decarboxylase activities. On a phylogenetic tree that was based on 16S ribosomal DNA gene sequences strain MBS1T was found among the rhodococci on an independent branch. On the basis of the chemotaxonomic and phenotypic characteristics of strain MBS1T and its phylogenetic position we suggest that this bacterium should be placed in a new species, Rhodococcus percolatus; the specific epithet was chosen because the organism was isolated by using an enriched percolator. The type strain is strain MBS1.
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PMID:Rhodococcus percolatus sp. nov., a bacterium degrading 2,4,6-trichlorophenol. 857

Highly specific detection of human alpha 1-acid glycoprotein (AGP) and asialo-alpha 1-acid glycoprotein (asialo-AGP) was made possible by use of a sandwich immunoassay. The glycoproteins were sandwiched between biotinylated and fluoresceinated polyclonal rabbit anti-human AGP antibodies. Additionally, asialo-AGP could be distinctly detected, apart from AGP, via the formation of a heterosandwich immunoassay using biotinylated polyclonal rabbit anti-human AGP and the lectin, fluoresceinated ricin toxin. Streptavidin was added to the formed immunocomplexes and the immunocomplexes captured on a biotinylated nitrocellulose membrane. The signal generator, urease conjugate of an anti-fluorescein antibody, was then bound to the complex on the membrane. The rate of pH change under microvolume conditions (0.6 microliters) was monitored using a silicon chip-based, light addressable potentiometer sensor. Results indicated that AGP and asialo-AGP can be detected to the 2 pg level when two antibodies are used to form the immunocomplex. Asialo-AGP can be detected down to 250 pg when the heterosandwich immunoassay is used; this assay exhibited no response up to 10 ng for native AGP or asialofetuin. Both immunoassays can be used to quantify the level of AGP and asialo-AGP in solution. Although the assay presented is very specific for AGP, asialo-AGP and terminal galactose, it is readily adaptable for the detection of any glycoprotein and terminal carbohydrate (or branched structure) by use of a protein-specific antibody and various lectins.
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PMID:Detection of human asialo-alpha(1)-acid glycoprotein using a heterosandwich immunoassay in conjunction with the light addressable potentiometric sensor. 887 21

Proteus mirabilis, associated with complicated urinary tract infection, expresses mannose-resistant/Proteus-like (MR/P) fimbriae. Expression of these surface structures, which mediate haemagglutination and have a demonstrated role in virulence, undergoes phase variation. By DNA sequence analysis, a 252 bp invertible element was found in the intergenic region between mrpl, the putative site-specific recombinase gene, and mrpA, the primary structural subunit gene. The invertible segment is flanked by identical 21 bp inverted repeats and the presumptive half-sites for recombinase binding show homology to those recognized by FimB and FimE encoded by the Escherichia coli fim (Type 1 fimbriae) gene cluster. When amplified by the polymerase chain reaction (PCR) from static broth cultures expressing MR/P fimbriae, the switch region was found in both ON and OFF positions. When PCR was used to amplify agar cultures which do not express the fimbriae, the switch region was OFF only. A canonical sigma 70 promoter inside the invertible element drives the transcription of mrpA when in the ON position; in the OFF position it is directed away from mrpA but does not appear to drive expression of mrpI. The mrpI gene was able to confer inversion of the mrp switch region in trans from both ON to OFF and OFF to ON. To examine the position of the switch in vivo, urine, bladder, and kidneys from mice transurethrally infected with P. mirabilis were used to prepare template DNA for PCR amplification. In the absence of urolithiasis (urease-mediated stone formation), the switch was found 100% in the ON position, a condition never observed following in vitro culture. We conclude that MR/P phase variation is regulated at the transcriptional level by the action of MrpI on an invertible element and that there is strong selective pressure for the expression of MR/P fimbriae in vivo.
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PMID:In vivo phase variation of MR/P fimbrial gene expression in Proteus mirabilis infecting the urinary tract. 907 37

Proteus mirabilis is a common causative agent of human urinary tract infections, especially in catheterized patients and in those patients with structural abnormalities of the urinary tract. In addition to the production of hemolysin and urease, fimbriae-mediated adherence to uroepithelial cells and kidney epithelium may be essential for virulence of P. mirabilis. A single P. mirabilis strain is capable of expressing several morphologically distinct fimbrial species, which can each be favoured by specific in vitro growth conditions. The fimbrial species reported to date include mannose-resistant/Proteus-like fimbriae, ambient temperature fimbriae, P. mirabilis fimbriae, and nonagglutinating fimbriae (NAF). Here, using intact bacteria or purified NAF as immunogens, we have generated the first reported NAF-specific monoclonal antibodies (mAbs). Bacteria expressing NAF as their only fimbrial species adhered strongly to a number of cell lines in vitro, including uroepithelial cell lines. Binding of P. mirabilis was markedly reduced following preincubation with NAF-specific mAbs and Fab fragments. The presence of NAF with highly conserved N-terminal sequences on all P. mirabilis strains so far examined, combined with the ability of both anti-NAF mAbs and purified NAF molecules to inhibit P. mirabilis adherence in vitro, suggests that NAF may contribute to the pathogenesis of P. mirabilis.
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PMID:The expression of nonagglutinating fimbriae and its role in Proteus mirabilis adherence to epithelial cells. 930 81

We examined the taxonomic position of seven Aeromonas isolates, recovered from Flemish and Scottish drinking water production plants and reservoirs, which were previously recognized by numerical analysis of genomic AFLP fingerprints as members of an unknown Aeromonas taxon that most closely resembled the species Aeromonas bestiarum (DNA hybridization group [HG] 2). The new phenotypic and DNA-DNA hybridization data obtained in this study show that the A. bestiarum-like strains constitute a separate Aeromonas species, for which the name Aeromonas popoffii sp. nov. is being proposed. The new species exhibited an internal DNA relatedness ranging from 79 to 100% and was 22 to 63% related to the type or reference strains of other Aeromonas spp. The highest DNA binding values were determined with A. bestiarum (51 to 63%), followed by Aeromonas hydrophila sensu stricto (HG1; 50 to 60%) and Aeromonas salmonicida (HG3; 39 to 55%). Although fingerprints generated by ribotyping and cellular fatty acid analysis often were highly similar, minor differences between the respective fingerprints were of significance for the differentiation of A. popoffii from its closest taxonomic neighbors, HG1, HG2, and HG3. Phenotypically, all seven strains of A. popoffii were positive for acid and gas production from D-glucose and glycerol, growth in KCN broth, arginine dihydrolase, DNase, Voges-Proskauer reaction, and resistance to vibriostatic agent O/129 and ampicillin but displayed negative reactions for production of urease, tryptophan deaminase, ornithine decarboxylase, and lysine decarboxylase (LDC). None of the strains displayed strong hemolytic activity. The lack of D-sucrose fermentation and LDC production and the ability to utilize DL-lactate as the sole energy and carbon source were useful characteristics for the biochemical separation of A. popoffii from A. bestiarum. Other Aeromonas spp. could be differentiated phenotypically from the new species by at least two features. The chromosomal G+C content of A. popoffii ranges from 57.7 to 59.6 mol%. Strain LMG 17541 is proposed as the type strain.
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PMID:Aeromonas popoffii sp. nov., a mesophilic bacterium isolated from drinking water production plants and reservoirs. 933 24


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