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)

Renal tubular acidosis (type I) is characterized by alterations that lead to disturbed acidification in the tubule. As a result of these alterations, the excretion of uromucoid (formed in the distal tubule), citrate and glycosaminoglycan (GAG) is considerably reduced. There have been numerous investigations on changes in urine pH, citrate and calcium, but few, if any studies on the excretion of uromucoid and GAG. Apart from calcium, phosphate, pH and urease, the present study investigated the excretion of uromucoid, citrate and GAG in a collective of 41 stone patients with renal tubular acidosis (type I). We found that uromucoid excretion was reduced on 90.5%, GAG in 72.2% and citrate in 96% of cases. The reduction of uromucoid excretion in particular is characteristic of RTA I, and it has the function of a marker.
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PMID:[The significance of citrate, uromucoid and GAG for diagnosis of renal tubular acidosis in patients with urinary calculi]. 884 53

Although calcium oxalate stones are the most common type of calculi found in the United States, struvite or infection stones are quite common and generally pose a difficult treatment dilemma. The presence of urinary infection with a urease-producing organism is necessary for these stones to form. Proteus species account for the majority of infections that cause struvite stones in all age ranges. However, other organisms also produce urease and may be detected in conjunction with struvite calculi. Factors that may predispose one to urinary tract infections increase the likelihood of struvite stone formation. Several options are available for the treatment of existing struvite calculi. Smaller stones may be treated with primary shock-wave lithotripsy, whereas larger stones are more appropriately managed with percutaneous or combination procedures. Medical therapy to prevent recurrent stone formation is also an essential part of the treatment of these patients, as the risk of stone recurrence is extremely high. Antibiotic therapy and urease inhibitors perhaps offer the best form of preventative treatment available today.
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PMID:Struvite calculi. 889 Mar 98

The gravity-sensing organ of Aplysia californica consists of bilaterally paired statocysts containing statoconia, which are granules composed of calcium carbonate crystals in an organic matrix. In early embryonic development, Aplysia contain a single granule called a statolith, and as the animal matures, statoconia production takes place. The objective of this study was to determine the effect of hypergravity on statoconia production and homeostasis and explore a possible physiologic mechanism for regulating this process. Embryonic Aplysia were exposed to normogravity or 3 x g or 5.7 x g and each day samples were analyzed for changes in statocyst, statolith, and body dimensions until they hatched. In addition, early metamorphosed Aplysia (developmental stages 7-10) were exposed to hypergravity (2 x g) for 3 weeks, and statoconia number and statocyst and statoconia volumes were determined. We also determined the effects of hypergravity on statoconia production and homeostasis in statocysts isolated from developmental stage 10 Aplysia. Since prior studies demonstrated that urease was important in the regulation of statocyst pH and statoconia formation, we also evaluated the effect of hypergravity on urease activity. The results show that hypergravity decreased statolith and body diameter in embryonic Aplysia in a magnitude-dependent fashion. In early metamorphosed Aplysia, hypergravity decreased statoconia number and volume. Similarly, there was an inhibition of statoconia production and a decrease in statoconia volume in isolated statocysts exposed to hypergravity in culture. Urease activity in statocysts decreased after exposure to hypergravity and was correlated with the decrease in statoconia production observed. In short, there was a decrease in statoconia production with exposure to hypergravity both in vivo and in vitro and a decrease in urease activity. It is concluded that exposure to hypergravity downregulates urease activity, resulting in a significant decrease in the formation of statoconia.
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PMID:A mechanism of adaptation to hypergravity in the statocyst of Aplysia californica. 895 50

The aetiology of calcium oxalate stones, which are commonly believed to be sterile, has not yet been fully elucidated. Recent bacteriological studies and investigations using the scanning electron microscope have also shown microorganisms to be present in this type of stone. These microorganisms were assumed not to be able to split urea. To list the most common urease-negative bacteria established in the human urinary system, we isolated apparently urease-negative microorganisms from a consecutive series of 58 urinary stone-forming patients by using standard selecting agars. Pure strains were incubated in an inductive medium lacking all sources of nitrogen except urea. Induction of urease activity was monitored by a test based on the reaction of phenol/hypochlorite with ammonium ions. This test revealed whether the urease negativity of a strain indicated by the selective agar was optional or absolute. All strains we investigated by this method and which were classified by standard methods as urease-negative we found produced urease activity which was clearly measurable, though it was often comparatively small. In the light of these results, the matrix theory of calcium oxalate stone development will need some modifications.
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PMID:Potential contribution of optional urease-positive bacteria to idiopathic urinary calcium stone formation. I. Expression of urease activity in bacteria from the urinary tract that are commonly classified as urease-negative. 896 42

The effect of aminoglycosides on renal function was evaluated in 30 full-term infants who were treated within 24 h of birth with either amikacin (10 infants, group A), gentamicin (9 infants, group B), or netilmicin (10 infants, group C). Renal function was assessed before, during, and 48 h after discontinuation of therapy by measuring the plasma creatinine concentration (PCr), the fractional excretion of sodium (FENa), potassium, magnesium, phosphate (FEP), uric acid, and the urinary excretion of calcium (UCA/UCr ratio) immediately before (trough) and after (peak) the infusion of the aminoglycosides. The results were compared with 10 control newborns who did not receive antibiotics. Significant alterations in renal function were observed only during therapy with gentamicin (group B). These consisted of a sustained elevation of FENa and UCa/UCr ratio throughout therapy, a latent increase in FEP on the 7th day (P < 0.05), and lack of the normal postnatal decline of PCr in 3 of 9 infants (P < 0.01). These abnormalities persisted up to 2 days after discontinuation of therapy. Therapeutic doses of gentamicin may result in significant electrolyte disturbances in sick full-term infants.
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PMID:Effect of aminoglycoside therapy on renal function in full-term infants. 897 4

Statoconia are calcium carbonate inclusions in the lumen of the gravity-sensing organ, the statocyst, of Aplysia californica. The aim of the present study was to examine the role of carbonic anhydrase and urease in statoconia mineralization in vitro. The experiments were performed using a previously described culture system (Pedrozo et al., J. Comp. Physiol. (A) 177:415-425). Inhibition of carbonic anhydrase by acetazolamide decreased statoconia production and volume, while inhibition of urease by acetohydroxamic acid reduced total statoconia number, but had no affect on statoconia volume. Inhibition of carbonic anhydrase initially increased and then decreased the statocyst pH, whereas inhibition of urease decreased statocyst pH at all times examined; simultaneous addition of both inhibitors also decreased pH. These effects were dose and time dependent. The results show that carbonic anhydrase and urease are required for statoconia formation and homeostasis, and for regulation of statocyst pH. This suggests that these two enzymes regulate mineralization at least partially through regulation of statocyst pH.
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PMID:Regulation of statoconia mineralization in Aplysia californica in vitro. 908 70

Renal lithiasis is a frequent disease which recurs in more than 60% of cases. Effective prevention of recurrence can be obtained once the cause has been identified. The laboratory investigation, based on clinical history, analysis of the stone and blood and urine assays, achieves this objective. As the stone is the main indicator of lithogenic disorders, the investigation must start by morphoconstitutional analysis of the stone by reliable physical methods. The results of this analysis guide the clinician towards the biochemical factors responsible for the lithogenic process and, in some cases, directly to certain infectious diseases, such as infections due to urease-positive bacteria, or metabolic diseases, such as primary hyperoxaluria, tubular acidosis or enzymatic deficits of purine metabolism, without forgetting drug causes, responsible for the formation of approximately one per cent of stones. Subsequent investigations guided by analysis of the stone are therefore much more selective and rational. When the stone is not available, the investigation, graduated according to the metabolic activity of the lithiasis, can be guided by its radiological appearance. Dynamic investigations are rarely necessary and must be reserved a second-line procedures for the most severe forms of calcium-dependent stones. In the absence of radiological data and when the stone has not been collected, a basic routine blood and urine investigation must be performed looking for laboratory factors potentially involved in the stone-forming process.
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PMID:[Metabolic assessment of urinary lithiasis in routine practice. Common task of nephrologists and urologists of the Lithiasis Committee of the French Association of Urology]. 923 85

We developed a new simple assay for potassium ion in serum using urea amidolyase (UAL) from yeast sp. The method is based on activation of the enzyme by potassium ion. We eliminated endogenous ammonium ion by use of glutamate dehydrogenase (GLDH), and then monitored the production of ammonium ion by UAL, urea, ATP, bicarbonate and magnesium ions. Ammonium ion was produced proportional to the potassium ion concentration and was determined by adding GLDH to produce NADP+ in the presence of 2-oxoglutarate and NADPH. We monitored the change of absorbance at 340 nm. The inhibitory effect of calcium ion to this assay was eliminated by adding glycoletherdiamine-N, N, N', N'-tetraacetic acid to the reaction. The within-assay coefficients of variation (CV) of this method were 0.9-1.55% (n = 10) at 3.32-6.18 mmol/L. Day-to-day CVs ranged from 1.49% to 2.46%. The analytical recovery was 96-108%. The correlation coefficient between the values obtained by our method (y) and those by the ion-selective electrode (ISE) method (x) was 0.994 (y = 1.032x-0.166 mmol/L, Syx = 0.110, n = 100). The presence of bilirubin, haemoglobin or other ions did not affect this assay, confirming the usefulness of this assay for clinical purposes.
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PMID:New enzymatic assay with urea amidolyase for determining potassium in serum. 924 70

To better understand the mechanisms that could modulate the formation of otoconia, calcium carbonate granules in the inner ear of vertebrate species, we examined statoconia formation in the gravity-sensing organ, the statocyst, of the gastropod mollusk Aplysia californica using an in vitro organ culture model. We determined the type of calcium carbonate present in the statoconia and investigated the role of carbonic anhydrase (CA) and urease in regulating statocyst pH as well as the role of protein synthesis and urease in statoconia production and homeostasis in vitro. The type of mineral present in statoconia was found to be aragonitic calcium carbonate. When the CA inhibitor, acetazolamide (AZ), was added to cultures of statocysts, the pH initially (30 min) increased and then decreased. The urease inhibitor, acetohydroxamic acid (AHA), decreased statocyst pH. Simultaneous addition of AZ and AHA caused a decrease in pH. Inhibition of urease activity also reduced total statoconia number, but had no effect on statoconia volume. Inhibition of protein synthesis reduced statoconia production and increased statoconia volume. In a previous study, inhibition of CA was shown to decrease statoconia production. Taken together, these data show that urease and CA play a role in regulating statocyst pH and the formation and maintenance of statoconia. CA produces carbonate ion for calcium carbonate formation and urease neutralizes the acid formed due to CA action, by production of ammonia.
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PMID:Evidence for the involvement of carbonic anhydrase and urease in calcium carbonate formation in the gravity-sensing organ of Aplysia californica. 926 17

Urinary catheters tend to block when biofilm from urease-producing organisms build up on the catheter surface. This is a locally-occurring process that influences and influenced by the composition of the urine. In this work we relate urine pH and calcium to catheter blockage and suggest how to reduce the rate of encrustation. Sixty patients with indwelling urinary catheters were studied, 26 of them being troubled by frequent blockage of their catheters, 34 of them not. A series of small urine samples were collected during a 24 h period. Urinary pH and calcium concentration were combined into discriminant functions designed to separate Blockers from Non-blockers and achieved a 95% correct classification. The results indicate that a high and uniform rate of fluid intake is mandatory for the patient with a tendency for catheter blockage. Excessive total fluid intake may be avoided by attention to uniformity. Other avoidable risk factors include: excess dietary calcium from certain protein supplements and antacids; excess dietary magnesium from certain beverages and antacids; alkali from effervescent tablets; excess dietary citrate from some fruit juices and cordials; intermittent dehydration from alcohol ingestion. Less tractable risk factors include infection of the urinary tract with urease-positive organisms, hypercalciuria of immobilisation, hyperhydrosis and postural oliguria. The processes involved in catheter encrustation and blockage provide a model for the formation of calculi in spinal cord injured patients. Therefore the above considerations may also be relevant to the management of stone disease in paraplegic and tetraplegic patients.
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PMID:Urinary catheter blockage depends on urine pH, calcium and rate of flow. 926 17


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