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)

Proteus mirabilis, a urease-producing uropathogen, causes serious urinary tract infections in humans. To specifically evaluate the contribution of urease to virulence, a mutation was introduced into P. mirabilis HI4320 by homologous recombination. Virulence was assessed in the CBA mouse model of ascending urinary tract infection. Twenty mice each were challenged transurethrally with P. mirabilis HI4320 and its urease-negative derivative (1 x 10(9) to 2 x 10(9) CFU). At 48 h animals were sacrificed and the mean log10 CFU per milliliter of urine (parent, 6.23; mutant, 4.19; P = 0.0014) or per gram of bladder (parent, 6.29; mutant, 4.28; P = 0.0002), left kidney (parent, 4.11; mutant, 1.02; P = 0.00009), and right kidney (parent, 4.11; mutant, 2.43; P = 0.036) were all shown to be significantly different. These data demonstrate a role for urease as a critical virulence determinant for uropathogenic P. mirabilis.
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PMID:Construction of a urease-negative mutant of Proteus mirabilis: analysis of virulence in a mouse model of ascending urinary tract infection. 218 Aug 21

Lowering supersaturation with respect to struvite and carbonate apatite is the most important prophylactic measure in patients with infection-induced kidney stone disease. This is best achieved by combining culture-specific antibiotics with urinary acidification. Urinary infection with non-urease-producing Escherichia coli, probably promoting struvite particle formation, must be eradicated. Possible measures for improving urothelial anti-adherence properties or reducing bacterial adherence are discussed.
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PMID:Prophylaxis of infection-induced kidney stone formation. 229 Dec 50

The efficacy of a diet designed to facilitate dissolution of feline magnesium ammonium phosphate (struvite) uroliths was evaluated in 30 cases of urolithiasis, sterile struvite uroliths dissolved in a mean of 36 days after initiation of dietary treatment. In 5 cases of urolithiasis, struvite urocystoliths associated with urease-negative bacterial urinary tract infection dissolved in a mean of 23 days after initiation of dietary and antimicrobial treatment. In 3 cases of urolithiasis, struvite urocystoliths associated with urease-positive staphylococcal urinary tract infection dissolved in a mean of 79 days after initiation of dietary and antimicrobial treatment. Dissolution of uroliths in cats fed the treatment diet was associated with concomitant remission of dysuria, hematuria, and pyuria, and reduction in urine pH and struvite crystalluria. In one case, a urocystolith composed of 100% ammonium urate, and in another case, a urolith composed of 60% calcium phosphate, 20% calcium oxalate, and 20% magnesium ammonium phosphate did not dissolve.
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PMID:Medical dissolution of feline struvite urocystoliths. 232 73

Struvite stones are formed as the result of urinary tract infection by urease-producing bacteria. Ultrastructural examination of calculi removed from a patient revealed bacteria incorporated throughout the stone matrix. Exopolysaccharide stained by ruthenium red was associated with most of the bacteria, but it represented only a small portion of the organic matrix in the stone. Localised deposits of calcium and phosphorus, components of carbonate-apatite, and magnesium, a struvite component, were detected in close proximity to the cells. Histochemical examinations revealed that several of the gram-negative bacteria within the stone matrix possessed high levels of urease activity. We propose that bacterial slime production, intimately involved in the initiation of stone matrix deposition, is less prominent in mature stones because of the increased incorporation of host-derived mucoproteins and mucopolysaccharides.
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PMID:Observations of the ultrastructure of infected kidney stones. 247 Sep 5

29 patients suffering from recurrent struvite stones and/or persistent urinary tract infection were analyzed retrospectively with a follow-up time of 10 +/- 6 years. A sanitation of the urease-positive urinary tract infection was possible in 12 patients (41%). After 10 out of 53 operations (19%) rest stones were found. An unilateral nephrectomy was done in 3 cases. Despite rest calculi and persistent urinary tract infection no further calculus growth or deterioration of renal function was found in most patients.
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PMID:[The prognosis of patients with struvite calculi with remaining/recurrent calculi and treatment refractory urinary tract infections]. 262 20

Proteus mirabilis, a common cause of urinary tract infection, produces a potent urease that hydrolyzes urea to NH3 and CO2, initiating kidney stone formation. Urease genes, which were localized to a 7.6-kilobase-pair region of DNA, were sequenced by using the dideoxy method. Six open reading frames were found within a region of 4,952 base pairs which were predicted to encode polypeptides of 31.0 (ureD), 11.0 (ureA), 12.2 (ureB), 61.0 (ureC), 17.9 (ureE), and 23.0 (ureF) kilodaltons (kDa). Each open reading frame was preceded by a ribosome-binding site, with the exception of ureE. Putative promoterlike sequences were identified upstream of ureD, ureA, and ureF. Possible termination sites were found downstream of ureD, ureC, and ureF. Structural subunits of the enzyme were encoded by ureA, ureB, and ureC and were translated from a single transcript in the order of 11.0, 12.2, and 61.0 kDa. When the deduced amino acid sequences of the P. mirabilis urease subunits were compared with the amino acid sequence of the jack bean urease, significant amino acid similarity was observed (58% exact matches; 73% exact plus conservative replacements). The 11.0-kDa polypeptide aligned with the N-terminal residues of the plant enzyme, the 12.2-kDa polypeptide lined up with internal residues, and the 61.0-kDa polypeptide matched with the C-terminal residues, suggesting an evolutionary relationship of the urease genes of jack bean and P. mirabilis.
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PMID:Proteus mirabilis urease: nucleotide sequence determination and comparison with jack bean urease. 268 33

Proteus mirabilis, a cause of serious urinary tract infection, produces urease, an important virulence factor for this species. The enzyme hydrolyzes urea to CO2 and NH3, which initiates struvite or apatite stone formation. Genes encoding urease were localized on a P. mirabilis chromosomal DNA gene bank clone in Escherichia coli by deletion analysis, subcloning, Bal31 nuclease digestion, transposon Tn5 mutagenesis, and in vitro transcription-translation. A region of DNA between 4.0 and 5.4 kilobases (kb) in length was necessary for urease activity and was located within an 18.5-kb EcoRI fragment. The operon was induced by urea and encoded a multimeric, cytoplasmic enzyme comprising subunit polypeptides of 8,000, 10,000, and 73,000 daltons that were encoded by a single polycistronic mRNA and transcribed in that order. Seventeen urease-negative transposon insertions were isolated that synthesized either none of the structural subunit polypeptides, the 8,000-dalton polypeptide alone, or both the 8,000- and 10,000-dalton subunit polypeptides. The molecular weight of the native enzyme was estimated to be 212,000 by Superose-6 chromatography. Homologous sequences encoding the urease of Providencia stuartii synthesized subunit polypeptides of similar sizes and showed a similar genetic arrangement. However, restriction maps of the operons from the two species were distinct, indicating significant divergence.
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PMID:Proteus mirabilis urease: genetic organization, regulation, and expression of structural genes. 284 Dec 83

We studied the biochemical properties of the urease of Staphylococcus saprophyticus and the possible role of the urease in experimental urinary tract infections. For this purpose, the nonhemagglutinating and nonadherent strain 9325, which was isolated from a case of symptomatic urinary tract infection, was used. The urease was shown to have a Km of 6.64 mM urea and a Vmax of 4.59 mumol NH3.min-1.mg-1. The enzyme was inhibited by acetohydroxamic acid in a noncompetitive manner. By means of Sephacryl S-300 column chromatography, we determined a mean molecular weight (+/- standard error of the mean) of 420,000 +/- 16,000. To assess the contribution of S. saprophyticus urease to uropathogenicity, a urease-negative mutant was constructed by nitrosoguanidine mutagenesis. In the rat model of ascending unobstructed urinary tract infection, higher numbers of CFU.gram of tissue-1 and more-severe lesions were detected with the parent strain. Moreover, bladder stones were found in animals infected with the urease-positive strain only. Interestingly, the difference in mean bacterial counts of the bladders was found to be significant by the Wilcoxon two-sample test (P less than 0.05), whereas that between the kidney bacterial counts was not. Immunoblot studies revealed a faint antibody response in rats infected with the mutant strain, although bacteria could still be detected in the kidneys after 7 days. Sera of animals challenged with the parent strain reacted strongly with many antigens of S. saprophyticus. Our data indicate that urease is a major factor for invasiveness of S. saprophyticus, especially in the tissue of the bladder, whereas persistence in the urinary tract and nephropathogenicity of this organism are governed by factors other than urease.
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PMID:Staphylococcus saprophyticus urease: characterization and contribution to uropathogenicity in unobstructed urinary tract infection of rats. 290 83

The comparative study of 44 isolates of Corynebacterium group D2, from urine, most frequently, shows the pathogenic role of these bacteria in urinary tract infection, with or without urinary stones. These microorganisms have an opportunistic behaviour in other non-urinary sites, and become pathogen in immunosuppressed conditions. The rapid tests as urease, glucose acidification, nitrate reductase, associated with multiple resistance to antibiotics (beta-lactams and aminosides) identify easily Corynebacterium group D2, from 48 h cultures under CO2 conditions. The results of MIC determination of 10 antibiotics, show the high activity (100% sensitivity) of vancomycin and pristinamycin, with MIC modes, respectively, 0.5 and 0.03 mg/l. These antibiotics are the most useful for the treatment of non-urinary infections. Among quinolones, the most active agents are ciprofloxacin and ofloxacin (MIC modes: 4 and 2 mg/l), so these antimicrobials could be used for the treatment of urinary tract infections caused by Corynebacterium group D2.
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PMID:[Corynebacterium group D2. Clinical study, biochemical identification and antibiotic sensitivity]. 313 26

Medical therapy is an effective method of canine struvite urolith dissolution. Recommendations include (1) eradication or control of urinary tract infection (if present), (2) use of calculolytic diets, and (3) administration of urease inhibitors to patients with persistent urinary tract infection caused by urease-producing microbes.
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PMID:Medical dissolution of canine struvite uroliths. 348 18


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