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)

A model of the catheterised bladder was used to test the ability of urease-producing urinary tract pathogens to encrust urethral catheters. Encrustation was assessed by determining the amounts of calcium and magnesium deposited on the catheters and visualised by scanning electron microscopy. Urease-positive Morganella morganii, Klebsiella pneumoniae, and Pseudomonas aeruginosa failed to raise the urinary pH and form crystalline biofilms. In contrast, strains of Proteus mirabilis, Proteus vulgaris, and Providencia rettgeri generated alkaline urine (pH 8.3-8.6) and extensive catheter encrustation within 24 h.
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PMID:Studies on the formation of crystalline bacterial biofilms on urethral catheters. 983 68

This case report describes a patient with severe back pain and radiculopathy. She was found to have a facet cyst within the lumbar spine that appeared to contain calcium on MRI and CT. Upon aspiration the cyst was found to contain calcium ammonium phosphate (struvite) and calcium phosphate (hydroxyapatite). Ammonia production in the presence of urease-producing bacteria is responsible for the production of struvite in the human body. We postulate that there was a prior infection of the facet with urease-producing bacteria, thus accounting for the production of the struvite within the facet cyst.
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PMID:Unusual facet cyst containing struvite and hydroxyapatite. 1128 37

Catalytic decomposition of urea by urease in aqueous calcium chloride solutions was used to rapidly prepare calcium carbonate polymorphs at room temperature. The nature of the resulting particles depended on the concentration of the enzyme and, in a strong manner, on the agitation of the reacting solutions. In an undisturbed system an amorphous precipitate is formed first, which readily crystallized to vaterite and upon aging changed to calcite. Under the influence of magnetic stirring, the amorphous phase could be not observed; instead smaller particles were initially obtained, which aggregated to vaterite and calcite. Similarly, the application of ultrasonic energy produced small vaterite particles at the early stages. It is apparent that enzyme macromolecules are important in the development of calcite faces and, as such, they exert significant influence on calcite morphology, without being present in detectable amounts in the resulting solids. Copyright 2001 Academic Press.
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PMID:Homogeneous Precipitation of Calcium Carbonates by Enzyme Catalyzed Reaction. 1135 Jan 56

The virulence of a urease-negative mutant of uropathogenic Proteus mirabilis and its wild-type parent strain was assessed by using a CBA mouse model of catheterized urinary tract infection. Overall, catheterized mice were significantly more susceptible than uncatheterized mice to infection by wild-type P. mirabilis. At a high inoculum, the urease-negative mutant successfully colonized bladders of catheterized mice but did not cause urolithiasis and was still severely attenuated in its ability to ascend to kidneys. Using confocal laser scanning microscopy and scanning electron microscopy, we demonstrated the presence of P. mirabilis within the urease-induced stone matrix. Alizarin red S staining was used to detect calcium-containing deposits in bladder and kidney tissues of P. mirabilis-infected mice.
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PMID:Visualization of Proteus mirabilis within the matrix of urease-induced bladder stones during experimental urinary tract infection. 1174 5

Infection stones (ammonium magnesium phosphate) and catheter encrustations have a common cause-urease producing microorganisms. With their rapid growth and frequent recurrences, infection stones are among the most troublesome of urinary system stones. For many patients with a long-term indwelling catheter, encrustations can be a severe problem. Urine composition is important, because, urine calcium enhances the crystallization process and urine citrate inhibits it. The role of non-urease producing microorganisms in stone forming processes is not well understood. Stones can now be successfully treated with a low morbidity index by percutaneous stone surgery or extracorporeal shock wave lithotripsy (ESWL) and recurrence of stone formation is then avoided by prolonged antibiotic treatment and oral citrate. Catheter encrustations and damage caused by ammonia released during urease activity can, however, be a serious problem in patients with indwelling catheters and our remedies are unsatisfactory.
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PMID:Uropathogens and urinary tract concretion formation and catheter encrustations. 1213 38

Two general strategies have been adopted to develop catheter materials that resist encrustaion by bacterial biofilms: (a) the incorporation of antimicrobial agents into the polymers and (b) the production of materials with surface properties which prevent the adherence of bacterial cells. Our experience to develop non-adherent surfaces which abstracts design from nature is reported. Compounds based on 2-methacryloloxyethylphosphorylcholine co-polymerised with long-chain alkyl methacrylates have been produced which have structural and surface properties similar to those of the outer membranes of erythrocytes. These PC-coatings have been applied onto catheter base materials where they produce polar surfaces that are extremely hydrophilic. In experiments using a laboratory model of the catheterised bladder we found that the PC-coatings did not reduce colonisation of latex or silicone catheters by crystalline Proteus mirabilis biofilm. There were no significant difference between the amounts of calcium and magnesium salts deposited on coated and non-coated catheters. In a further set of experiments the PC-coatings did not significantly increase the mean times for which catheters drained freely. In a parallel clinical study, the performance of PC-coated ureteral stents was investigated. Scanning electron microscopy and bacteriological analysis on 44 PC-coated stents that had been implanted in patients for 12-week periods and 28 control stents suggested that the PC-coated devices were less vulnerable to encrustation and colonisation by bacterial biofilm than normal stents. It was of interest that in contrast to encrusted catheters, urease producing species such as P. mirabilis were rarely isolated from the stents. The main organisms colonising the stents were enterococci and coagulase-negative staphylococci. These results suggest that the mechanisms of catheter and stent encrustation may be different and require different strategies for control.
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PMID:Strategies for the control of catheter encrustation. 1213 40

With an aerobic incubation test, this paper studied the response of soil urease, nitrate reductase, nitrite reductase, and hydroxylamine reductase to urease inhibitor hydroquinone (HQ) applied in combination with nitrification inhibitor encapsulated calcium carbide (HQ + ECC) or dicyandiamide (HQ + DCD). The results showed that HQ + DCD could inhibit urease activity and increase activities of nitrate reductase, nitrite reductase, and hydroxylamine reductase significantly in comparison with CK, HQ and HQ + ECC. Under the condition of our test, there existed a significant relationship between soil urease, nitrate reductase, nitrite reductase, and hydroxylamine reductase activities and soil NH4+ and NO3- contents, NH3 volatilization and N2O emission rate, and regression analysis indicated that there were significantly positive relationships between soil urease, nitrite reductase and hydroxylamine reductase activities.
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PMID:[Response of N transformation related soil enzyme activities to inhibitor applications]. 1256 Nov 70

While calcium oxalate and calcium phosphate make up at least 80% of all kidney stones, infection-induced and uric acid stones occur in 10% and 8%, respectively. Although any type of stone may become infected, the term "infection stones" means that stone formation exclusively depends on urease-producing bacteria. The splitting of urea leads to a rise in urinary pH which may induce crystallization of struvite (magnesium-ammonium-phosphate), the major constituent of infection stones, or carbonate apatite. Struvite stones account for the majority of staghorn calculi. They can grow quite large and may fill the entire collecting system. Patients with struvite stones may present with acute flank pain or remain completely asymptomatic. The cure of infection stones requires complete removal of the stone material. For uric acid crystallization and stone formation, low urine pH (below 5.5) is a more important risk factor than increased urinary uric acid excretion. Main causes of low urine pH are tubular disorders (including gout), chronic diarrheal states or severe dehydration. Accordingly, the treatment of uric acid stones consists not only of hydration (urine volume above 2000 ml per day), but mainly of urine alkalinization to pH values between 6.2 and 6.8. Urinary uric acid excretion can be reduced by a low-purine diet as well as--in case of recurrent uric acid stones and/or gout--by allopurinol. Cystinuria is a rare hereditary gene disorders with impaired tubular reabsorption of cystine. Stone formation occurs as a consequence of cystine's relatively low solubility at urine pH levels below 8. Only symptomatic diet and drug treatments are currently available, with urine dilution and urine alkalinization being the most efficient ones. Cystine stones respond poorly to shockwave lithotripsy, so that invasive procedures may regularly be necessary. 2,8-dihydroxy-adenine stones occur as a consequence of an enzyme deficiency that involves purine metabolism. These resulting stones are not visible by fluoroscopy and are therefore often misinterpreted as uric acid stones. Low-purine diet and allopurinol reduce the frequency of stone formation.
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PMID:[Pathophysiology, diagnosis and conservative therapy of non-calcium kidney calculi]. 1264 87

The relationship between urinary infections and stone formation has been recognized since antiquity and it has been over a century since bacterial degradation of urea was postulated to cause struvite stones. Specific therapy for urease-producing bacteria, such as urease-inhibitors and antibiotics, has allowed for treatment for this subset of urinary stones. Future directions for research include development of novel urease-inhibitors and chemicals to enhance the protective glycosaminoglycan layer. An improved understanding of the pathogenesis of calcium-based stones has led to the discovery of potential roles for nanobacteria and Oxalobacter formingenes. Methods of altering intestinal regulation of oxalate by reintroduction of lactic acid bacteria may significantly impact the treatment of calcium oxalate stones. The use of catheters, both urethral and ureteral, is common in the urinary tract and is associated with significant morbidity, primarily from associated infections. Catheters to prevent bacterial colonization and formation of biofilms have been created using various coatings, including ciprofloxacin, hydrogel, and silver. Use of these types of catheters may minimize infections and encrustation inherent with their placement in the urinary tract.
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PMID:Infections and urinary stone disease. 1267 63

Formation of infectious urinary calculi is the most common complication accompanying urinary tract infections by members of the genus Proteus. The major factor involved in stone formation is the urease produced by these bacteria, which causes local supersaturation and crystallization of magnesium and calcium phosphates as carbonate apatite [Ca(10)(PO(4))(6).CO(3)] and struvite (MgNH(4)PO(4).6H(2)O), respectively. This effect may also be enhanced by bacterial polysaccharides. Macromolecules of such kind contain negatively charged residues that are able to bind Ca(2+) and Mg(2+), leading to the accumulation of these ions around bacterial cells and acceleration of the crystallization process. The levels of Ca(2+) and Mg(2+) ions bound by whole Proteus cells were measured, as well as the chemical nature of isolated LPS polysaccharides, and the intensity of the in vitro crystallization process was compared in a synthetic urine. The results suggest that the sugar composition of Proteus LPS may either enhance or inhibit the crystallization of struvite and apatite, depending on its chemical structure and ability to bind cations. This points to the increased importance of endotoxin in urinary tract infections.
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PMID:Crystallization of urine mineral components may depend on the chemical nature of Proteus endotoxin polysaccharides. 1274 65


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