Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Detection of alkaline urine traditionally sends an alert to the clinician to consider the presence of a urease-producing bacterial urinary tract infection, postprandial alkaline tide, or the ingestion of a diet that is nonacidifying. In the cat of this report, acid urine was produced while the cat was in the home environment, but alkaline urine was produced following the stress of a long trip to the veterinarian's office. Stress-induced respiratory alkalosis was highly suspected as the cause for the alkaline urine. If traditional causes for alkaline urine are not apparent for cats that produce alkaline urine at the veterinary clinic, we suggest that urinary pH be determined on samples collected in the home.
 ...
PMID:Intermittent alkaline urine in a cat fed an acidifying diet. 892 88

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.
 ...
PMID:In vivo phase variation of MR/P fimbrial gene expression in Proteus mirabilis infecting the urinary tract. 907 37

Perineal urethrostomies are associated with complications that may mimic primary causes of feline lower urinary tract disorders. Though postoperative urethral strictures may be minimized by proficiency with an effective surgical technique, removal of the distal urethra may result in bacterial urinary tract infections in 25% to 30% of patients after surgery. Urinary tract infections caused by urease-producing microbes may induce struvite urolith formation. Thus the prophylactic benefits of minimizing recurrent urethral obstruction by urethrostomy must be weighed against a long-term predisposition to recurrent bacterial urinary tract infection and urolith formation.
 ...
PMID:Feline perineal urethrostomy: a potential cause of feline lower urinary tract disease. 915 52

Proteus mirabilis, a cause of complicated urinary tract infection, expresses urease when exposed to urea. While it is recognized that the positive transcriptional activator UreR induces gene expression, the levels of expression of the enzyme during experimental infection are not known. To investigate in vivo expression of P. mirabilis urease, the gene encoding green fluorescent protein (GFP) was used to construct reporter fusions. Translational fusions of urease accessory gene ureD, which is preceded by a urea-inducible promoter, were made with gfp (modified to express S65T/V68L/S72A [B. P. Cormack et al. Gene 173:33-38, 1996]). Constructs were confirmed by sequencing of the fusion junctions. UreD-GFP fusion protein was induced by urea in both Escherichia coli DH5alpha and P. mirabilis HI4320. By using Western blotting with antiserum raised against GFP, expression level was shown to correlate with urea concentration (tested from 0 to 500 mM), with highest induction at 200 to 500 mM urea. Fluorescent E. coli and P. mirabilis bacteria were observed by fluorescence microscopy following urea induction, and the fluorescence intensity of GFP in cell lysates was measured by spectrophotofluorimetry. P. mirabilis HI4320 carrying the UreD-GFP fusion plasmid was transurethrally inoculated into the bladders of CBA mice. One week postchallenge, fluorescent bacteria were detected in thin sections of both bladder and kidney samples; the fluorescence intensity of bacteria in bladder tissue was higher than that in the kidney. Kidneys were primarily infected with single-cell-form fluorescent bacteria, while aggregated bacterial clusters were observed in the bladder. Elongated swarmer cells were only rarely observed. These observations demonstrate that urease is expressed in vivo and that using GFP as a reporter protein is a viable approach to investigate in vivo expression of P. mirabilis virulence genes in experimental urinary tract infection.
 ...
PMID:Use of green fluorescent protein to assess urease gene expression by uropathogenic Proteus mirabilis during experimental ascending urinary tract infection. 942 75

A boy with a neuropathic bladder and a single hydronephrotic kidney developed hyperammonaemic encephalopathy during a urinary tract infection with Klebsiella oxytoca. Although particularly associated with Proteus infections and prune belly syndrome, hyperammonaemia can complicate infection with any urease-producing bacteria if there is urinary stasis.
 ...
PMID:Hyperammonaemia due to Klebsiella infection in a neuropathic bladder. 981 90

Two types of canine struvite uroliths have been recognized: infection-induced struvite is the most common type; sterile struvite is uncommonly recognized. Infection-induced struvite is most commonly associated with urease-producing staphylococcal UTI. For dogs that qualify, medical dissolution is an effective method of treatment. Medical dissolution protocols encompass: (1) eradication or control of UTI; (2) use of calculolytic diets; and (3) administration of urease inhibitors to patients with persistent UTI caused by urease-producing microbes.
 ...
PMID:Medical dissolution and prevention of canine struvite urolithiasis. Twenty years of experience. 1002 53

The most important phosphates involved in urinary stone disease are carbonate apatite, brushite, and struvite. Overall, phosphate stones account for 12-20% of all stones, with a downward trend for struvite and an increase in carbonate apatite being observed in the last decade. The physicochemical basis for the formation of phosphate calculi is supersaturation. Once the solubility product has been exceeded, a metastable process of supersaturation begins, with slow crystalline growth. If a critical limit of supersaturation is exceeded, large-scale spontaneous precipitation of crystals occurs in a second stage. No urinary tract infection is involved in brushite stone formation. Although infection is not a prerequisite for the formation of carbonate apatite stones, infective conditions favor carbonate apatite formation. Struvite is the characteristic infection calculus, formed as a result of urinary tract infection with urease-producing bacteria. During the first episode of urinary stone disease a definitive diagnosis of the type of stone involved is very difficult without analysis of the latter by infrared spectroscopy or X-ray diffraction. In recurrent disease, appropriate treatment can be initiated on the basis of the previous stone analysis in the majority of cases. The best means of preventing recurrent disease involving any type of phosphate stone is definitive calculus removal by shock-wave lithotripsy, percutaneous stone removal, or open surgery (especially in children). Chemolysis via acidification of the urine with Suby G solution or hemicidrin supported by oral acidification, achieved by the metabolism of L-methionine, and antibiotic therapy (especially for infectious stones) are important adjuvant modalities of therapy. After therapy of phosphate stones, metaphylaxis involving controlled urinary acidification with L-methionine supports the treatment of infection and, at a pH value of less than 6.2 and urine dilution to 2.5 l/24 h, prevents the crystallization of struvite, brushite, and carbonate apatite.
 ...
PMID:Causes of phosphate stone formation and the importance of metaphylaxis by urinary acidification: a review. 1055 50

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.
 ...
PMID:Visualization of Proteus mirabilis within the matrix of urease-induced bladder stones during experimental urinary tract infection. 1174 5

Proteus mirabilis is a documented cause of urinary tract infection (UTI) in the complicated urinary tract. Urease-mediated urea hydrolysis is responsible for both virulence of the organism and the ability to cause urolithiasis. A urease-negative mutant of P. mirabilis is unable to initiate stone formation and colonizes the kidney at a significantly lower rate. The considerable pathology caused by P. mirabilis warrants the development of a vaccine. We have initiated the advancement of vaccine studies and have determined that the MR/P fimbria, a surface adhesin of P. mirabilis, is a promising vaccine candidate. Successful vaccination would be expected both to prevent colonization by P. mirabilis and urolithiasis.
 ...
PMID:Vaccines for Proteus mirabilis in urinary tract infection. 1213 33

Infection stones make up approximately 15% of urinary stone diseases and are thus an important group. These stones are composed of struvite and/or carbonate apatite. The basic precondition for the formation of infection stones is a urease positive urinary tract infection. Urease is necessary to split urea to ammonia and CO(2). As a result, ammonia ions can form and at the same time alkaline urine develops, both being preconditions for the formation of struvite and carbonate apatite crystals. When these crystals deposit themselves infection stones form. If these infections are not treated and the stones are not removed, the kidney will be damaged. For stone removal modern methods are available, e.g. ESWL and/or instrumental urinary stone removal. Here especially less invasive methods are preferable. Any treatment must be adjusted to the patient individually. Patients should be examined frequently for recurrent urinary tract infections and stone recurrences and, newly arising infections must be resolutely treated. Good therapy and prophylaxis are possible with present-day treatment modalities.
 ...
PMID:Urinary infection stones. 1213 39


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>