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:3.5.1.5 (urease)
7,257 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Calculi formed in 26 of 87 patients (30%) following augmentation enterocystoplasty, of which 23 formed within the reservoir, at a mean interval of 25 months postoperatively. The calculi were composed principally of triple phosphates suggesting an important etiological role of bacteriuria and the urease reaction. Open cystolithotomy was the most successful means of removing the calculi.
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PMID:Lithogenic properties of enterocystoplasty. 164 May 25

Catheter-associated urinary tract infections (UTIc) remain the most common nosocomial infection. Although usually benign, UTIc cause bacteremia in 2-4% of patients and have been associated with a case fatality rate three times as high as nonbacteriuric patients. Risk factors for UTIc identified in multivariate analyses include increasing duration of use, female sex, absence of systemic antibiotics, and disconnection of the catheter-collecting tube junction. Recent studies suggest that most episodes of low colony count bacteriuria (10(2)-10(4) cfu/ml) rapidly progress to high (greater than or equal to 10(5)/ml) colony counts within 24-48 hours. In persons with long-term catheterization, bacteriuria inevitably develops and the infecting strains change frequently. In this setting, Proteus and Morganella species produce catheter encrustations and persistent bacteriuria. Routes of bacterial entry have been well defined and differ by gender, with the periurethral route predominating in women and the intraluminal route in men. Growth of bacteria in biofilms on the inner surface of catheters promotes encrustation and may protect bacteria from antimicrobial agents. Bacterial virulence factors have not been well characterized in UTIc, but fimbrial adhesins have been associated with bacterial persistence in the catheterized urinary tract, and urease production has been associated with stone formation and catheter encrustation. Recent efforts to prevent UTIc have focused mainly on preventing bacterial entry to the urinary tract or eradicating bacteriuria after its onset and have been largely unsuccessful. Systemic antimicrobials, sealed tubing and catheter junctions, silver ion-coated catheters, and antiseptics in the collecting bag have all been efficacious in one or more controlled trials. Failure to stratify patients by major risk factors, especially gender, antimicrobial exposure, and catheter duration, makes interpretation of many trials difficult. Further research in the areas of innovative catheter system design, bacterial-host epithelial cell interaction, and targeted antimicrobial prophylaxis seem the most likely approaches to controlling UTIc in the future.
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PMID:Catheter-associated urinary tract infections: epidemiology, pathogenesis, and prevention. 192 94

Proteus mirabilis, a common agent of nosocomially acquired and catheter-associated bacteriuria, can cause acute pyelonephritis. In ascending infections, bacteria colonize the bladder and ascend the ureters to the proximal tubules of the kidney. We postulate that Proteus species uses the HpmA hemolysin and urease to elicit tissue damage that allows entry of these bacteria into the kidney. To study this interaction, strains of Proteus mirabilis and P. vulgaris and their isogenic hemolysin-negative (hpmA) or isogenic urease-negative (ureC) constructs were overlaid onto cultures of human renal proximal tubular epithelial cells (HRPTEC) isolated from kidneys obtained by immediate autopsy. Cytotoxicity was measured by release of soluble lactate dehydrogenase (LDH). Two strains of P. mirabilis inoculated at 10(6) CFU caused a release of 80% of total LDH after 6 h, whereas pyelonephritogenic hemolytic Escherichia coli CFT073 released only 25% at 6 h (P less than 0.012). Ten P. mirabilis isolates and five P. vulgaris isolates were all hemolytic and cytotoxic and produced urease which was induced by urea. The HpmA hemolysin is apparently responsible for the majority of cytotoxicity in vitro since the hemolysin-negative (hpmA) mutants of P. mirabilis and P. vulgaris were significantly less cytotoxic than wild-type strains. P. mirabilis WPM111 (hemolysin negative) was used to test the effect of urease-catalyzed urea hydrolysis on HRPTEC viability. In the presence of 50 mM urea, WPM111 caused the release of 42% of LDH versus 1% at 6 h in the absence of substrate (P = 0.003). We conclude that the HpmA hemolysin of Proteus species acts as a potent cytotoxin against HRPTEC. In addition, urease apparently contributes to this process when substrate urea is available.
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PMID:Cytotoxicity of the HpmA hemolysin and urease of Proteus mirabilis and Proteus vulgaris against cultured human renal proximal tubular epithelial cells. 203 63

Proteus mirabilis, a common cause of urinary tract infection, can lead to serious complications including pyelonephritis. Adherence factors, urease, and hemolysin may be virulence determinants. These factors were compared for bacteria cultured from 16 patients with acute pyelonephritis and 35 with catheter-associated bacteriuria and for 20 fecal isolates. Pyelonephritis isolates were more likely (P less than .05) to express the mannose-resistant/Proteus-like (MR/P) hemagglutinin in the absence of mannose-resistant/Klebsiella-like (MR/K) hemagglutinin than were catheter-associated or fecal isolates. Pyelonephritis isolates produced urease activity of 63 +/- 27 (mean +/- SD) mumol of NH3/min/mg of protein, not significantly different from catheter-associated or fecal isolates. Hybridization of Southern blots of P. mirabilis chromosomal DNA with two urease gene probes demonstrated that urease gene sequences were conserved in all isolates. Geometric mean of reciprocal hemolytic titers for pyelonephritis isolates was 27.9; for urinary catheter isolates, 18.0; and for fecal isolates, 55.7 (not significantly different, P greater than .1). Although in vivo expression of urease and hemolysin may not be reliable indexes of virulence, MR/P hemagglutination in the absence of MR/K hemagglutination may be necessary for development of pyelonephritis.
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PMID:Hemagglutinin, urease, and hemolysin production by Proteus mirabilis from clinical sources. 217 24

Morganella morganii, a very common cause of catheter-associated bacteriuria, was previously classified with the genus Proteus on the basis of urease production. M. morganii constitutively synthesizes a urease distinct from that of other uropathogens. The enzyme, purified 175-fold by passage through DEAE-Sepharose, phenyl-Sepharose, Mono-Q, and Superose 6 chromatography resins, was found to have a native molecular size of 590 kilodaltons and was composed of three distinct subunits with apparent molecular sizes of 63, 15, and 6 kilodaltons, respectively. Amino-terminal analysis of the subunit polypeptides revealed a high degree of conservation of amino acid sequence between jack bean and Proteus mirabilis ureases. Km for urea equalled 0.8 mM. Antiserum prepared against purified enzyme inhibited activity by 43% at a 1:2 dilution after 1 h of incubation. All urease activity was immunoprecipitated from cytosol by a 1:16 dilution. Antiserum did not precipitate ureases of other species except for one Providencia rettgeri strain but did recognize the large subunits of ureases of Providencia and Proteus species on Western blots (immunoblots). Thirteen urease-positive cosmid clones of Morganella chromosomal DNA shared a 3.5-kilobase (kb) BamHI fragment. Urease gene sequences were localized to a 7.1-kb EcoRI-SalI fragment. Tn5 mutagenesis revealed that between 3.3 and 6.6 kb of DNA were necessary for enzyme activity. A Morganella urease DNA probe did not hybridize with gene sequences of other species tested. Morganella urease antiserum recognized identical subunit polypeptides on Western blots of cytosol from the wild-type strain and Escherichia coli bearing the recombinant clone which corresponded to those seen in denatured urease. Although the wild-type strain and recombinant clone produced equal amounts of urease protein, the clone produced less than 1% of the enzyme activity of the wild-type strain.
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PMID:Morganella morganii urease: purification, characterization, and isolation of gene sequences. 234 35

The pathogenesis and epidemiology of infection stones are well understood. While percutaneous lithotripsy and extracorporeal shock wave lithotripsy have emerged as the mainstay of extirpative therapy, surgical lithotomy is the standard to which other therapies must be compared. Adjunctive therapy with pharmacological agents that inhibit urease with few side effects and effective urinary acidifiers favor chemolysis. Diet and chemotherapy offer the hope of slowing stone growth and/or recurrence in patients with chronic urease-producing bacteriuria.
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PMID:Infection stones. 264 35

We investigated 158 cases of urinary stones (infection stones 56, metabolic stones 102) with special reference to pyuria, bacteriuria, stone culture and urease activities of isolated bacteria. Abacterial pyuria was noted in 9 out of 49 (18%) infection stones and in 53 of 77 (69%) metabolic stones. Bacteriuria was noted in 79% of the infection stones and 26% of the metabolic stones. Sixty-seven percent of the infection stones were infected with mainly urea splitting bacteria such as Proteus mirabilis and Staphylococcus. Twenty-three percent of metabolic stones were also infected. Though E. coli, a non-urea splitting bacteria, was isolated most frequently from metabolic stones, urease positive Staphylococcus and Pseudomonas were also isolated. Bacteria within stones could be predicted on the basis of urine culture results of only 20 of 41 infection stones and 8 of 24 metabolic stones. These facts are useful for selection of some antibiotics in the treatment of urinary tract infections associated with urinary calculi. Urinary infections of urea splitting bacteria in infection stones are thought to be initial factors of stone formation and those of non-urea splitting bacteria are to be superimposed. However, urea splitting bacteria in metabolic stones may convert them into infection stones in future.
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PMID:[Urinary tract infection associated with urinary calculi. 1. The significance of urinary tract infection in urinary calculi]. 280 72

Long-term urethral catheterization (greater than or equal to 30 days), a management technique for urinary incontinence, results in polymicrobial bacteriuria. We frequently found urease-producing bacteria: of 1,135 weekly urine specimens from 32 long-term-catheterized patients, 86% had urease-positive bacterial species at greater than or equal to 10(5) CFU/ml. The most common species were Proteus mirabilis and Morganella morganii, each found in over half the specimens. P. mirabilis, but not other urease-positive species, was significantly associated with the 67 obstructions observed in 23 patients. M. morganii had a more complex association and in some way may protect the catheter from obstruction.
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PMID:Urease-positive bacteriuria and obstruction of long-term urinary catheters. 332 89

We determined the bacteriology of apparently infected renal calculi and accompanying urinary tract infections, and assessed the potential clinical value of the culture results. Twenty-two branched renal calculi from 16 patients were cultured. Fifteen calculi were infected with 1 or more urease-producing gram-negative enteric bacterium, 2 were infected with a urease-producing bacterium and a nonurease-producing organism, and 5 were sterile. Immersion of infected stones in antimicrobial solutions before culture reduced or eliminated surface bacteria but usually did not eradicate bacteria within the stone. The bacteriology of a stone or stones could be predicted on the basis of available urine culture results in only 2 of the 16 cases. These data suggest that branched renal calculi associated with bacteriuria usually are infected but that documentation of infection and identification of the infecting organism require culture of the stone.
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PMID:Bacteriology of branched renal calculi and accompanying urinary tract infection. 642 54

Struvite renal stones are caused by infection of the urine with bacteria that synthesize the enzyme urease. Ammonium is released by the breakdown of urea by urease, the urine becomes highly alkaline, and magnesium ammonium phosphate (struvite) and carbonate apatite crystallize. Incorporation of the infecting bacteria within the developing stone, results in a focus of infection that is resistant to conventional antimicrobial therapy, and which is manifested clinically by repeated urinary tract infection caused by persistent bacteriuria. Extracorporeal shock wave lithotripsy (ESWL) currently is accepted as the election treatment for most renal calculi. This trial examines the bacteriologic aspects pre and post-ESWL. Eighty adult patients, 47 females and 33 males, without clinical signs of urinary tract infections (UTI) were submitted to urine cultures pre and post-ESWL. The first 50 patients underwent during and post-ESWL, 150 blood cultures, which all proved to be negative, confirming very low risk of generalized sepsis. No patient presented fever, chills or rigors pre or postprocedures. With respect to urine cultures 43 patients (52.5%) had a pre-ESWL UTI, in comparison to 49 (60%) who had a UTI post-ESWL. The distribution of organisms pre and post-ESWL was as follows: Proteus mirabilis (22/22), Escherichia coli (11/11), Pseudomonas aeruginosa (4/5), Klebsiella pneumoniae (2/2), Enterobacter cloacae (0/1), Alcaligenes odorans (1/2) Enterococcus faecalis (1/3), Staphylococcus saprophyticus (1/2) and Candida albicans (1/1). In this study 6 patients presented bacteriuria post-ESWL probably due to bacteria from inside the calculi. According to these results, the risk of bacteremia seems to be very low. In 60% of staghorn renal stones we could demonstrate a bacterial infection.
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PMID:[Staghorn renal lithiasis treated with shock waves. Bacteriologic aspects]. 765 75


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