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)

Nitrogen-free analogues of essential amino acids, when administered with those essential amino acids for which analogues are ineffective or unavailable, exert three actions that may be beneficial in protein-deficient or protein-intolerant subjects. First, they bring about an increase in the concentrations of essential amino acids in the blood at the expense of the concentrations of certain non-essential amino acids, notably alanine and glutamine. This effect is most readily demonstrated in children with congenital defects of the urea cycle enzymes, but can also be seen during daily therapy of adults with portal-systemic encephalopathy. Second, these compounds promote nitrogen balance through their suppressive effect on urea synthesis (an effect not attributable to re-utilization of ammonia derived from urease action in the gut). This action is demonstrable in obese subjects who are already conserving nitrogen maximally at the end of a prolonged fast and can also be shown in the first week of fasting when the branched-chain keto acids alone are administered. In both situations, improved nitrogen conservation persists long after the analogues are metabolized, suggesting enzyme adaptations. In chronic uremics, nitrogen balance can be maintained in some (but not all) patients on very low nitrogen intakes. Third, these mixtures may delay or reverse the progressive decline in glomerular filtration rate characteristic of chronic renal failure in some cases: thus, for example, 5 of 6 patients taken off chronic dialysis have maintained lower serum urea concentrations without evidence of protein malnutrition for periods of 2-24 months.
 ...
PMID:Evidence for an anabolic action of essential amino acid analogues in uremia and starvation. 107 39

Two urease-based tests--the urease slide test and the radiolabeled urea breath test, are commonly used for the diagnosis of Helicobacter pylori infection of the stomach. The reliability of these tests in chronic uremia was compared with serological tests for H pylori antibodies, and with direct detection of the organism by microscopy or culture of gastric antral biopsies. Twenty-seven patients with chronic renal failure and dyspepsia underwent upper gastrointestinal endoscopy. Twelve of these patients (46%) were judged to be infected with H pylori on the basis of identification of the organism on microscopy or culture of antral biopsy. Both urease-based tests were able to determine H pylori status, despite the markedly increased concentrations of urea in the gastric juice found in chronic renal failure. The urease slide test performed on antral biopsies obtained at endoscopy proved reliable in determining H pylori status with no false-positive nor false-negative results after 20 minutes and 24 hours of incubation. The 14C-urea breath test also differentiated the infected from the uninfected patients. The 20-minute 14CO2 excretion (kg %dose/mmol CO2 x 100) ranged from 50 to 834 in the H pylori-infected patients, compared with 0.3 to 27 in the H pylori-noninfected patients (P < 0.0001); the 90-minute values ranged from 88 to 398 in the former, compared with 1 to 79 in the latter (P < 0.0001). The excretion of 14CO2 (derived from bacterial hydrolysis of ingested 14C-urea) was higher in all the uremic patients compared with nonuremic controls, and in half of the H pylori-noninfected uremic patients there was a late increase in 14CO2 excretion.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:The diagnosis of Helicobacter pylori infection in uremic patients. 146 85

The high plasma level of citrulline (Cit) is one of a number of abnormalities in the plasma amino acid pattern in chronic renal failure (CRF). Synthesis of arginine (Arg) from citrulline in the kidney is the major source of Arg for the body. In order to evaluate the renal activity of Arg synthesis in CRF, we studied arginine production in proximal convoluted tubules (PCT) isolated from male Sprague-Dawley rats 1 month after 5/6 nephrectomy and from sham-operated rats (n = 6 of each). PCT segments were incubated in a sealed chamber with 50 or 200 microM of [L-ureido 14C]-Cit (simulating in vivo plasma concentrations in healthy rats or rats with CRF, respectively). Arginase and urease were added to the medium to hydrolyze Arg into 14CO2 + NH3. 14CO2 was trapped in KOH and counted. Results showed that: (1) in CRF, Arg production per unit tubular length is increased in proportion to hypertrophy of PCT (x 1.5); (2) in CRF, as in the healthy kidney, Arg production increases with Cit concentration (x 2.5 from Cit 50 to 200 microM). Taking into account the hypertrophy and the elevation in Cit concentration, the increase in Arg production per unit length (x 3.6) is not sufficient to compensate for the reduction in nephron number. Most likely, a greater length of maximal tubule is recruited for renal Arg synthesis in CRF.
 ...
PMID:Arginine synthesis by the proximal convoluted tubule in rats with chronic renal failure. 146 41

Dialysis is the conventional treatment for chronic renal failure. It is cumbersome, expensive and time-consuming and thus alternate treatments have long been sought. A compact system consisting of haemoperfusion in series with ultrafiltration can nearly replace dialysis. A urea removal system is the only step required to complete this approach. The potential of combining a microencapsulated enzyme, urease, with an ammonium ion adsorbent, zirconium phosphate, to remove urea was examined in vitro. Urease converts urea to ammonium ions which are then adsorbed onto zirconium phosphate. This combination would be most effective in the intestinal tract. The capacity of zirconium phosphate is probably not enough to effect the removal of enough urea to completely replace dialysis in patients with no renal function. However, this system could potentially 1) delay the onset of dialysis therapy in patients who still have some renal function, either alone or in combination with haemoperfusion-ultrafiltration, or 2) reduce dialysis treatment times.
 ...
PMID:Orally ingested microencapsulated urease and an adsorbent, zirconium phosphate, to remove urea in kidney failure. 366 78

Ingestible adsorbents for the removal of uremic metabolites are being investigated as adjunctive therapy in the treatment of chronic uremia. In particular, a microcapsule product containing urease and zirconium phosphate (UZP) has been investigated for removing urea. A dog model, simulating chronic uremia, was developed to investigate: (1) the concentration of various nitrogenous metabolites (urea, creatinine, and uric acid) in the GI tract, (2) flux rates of H2O and various nitrogenous metabolites in the GI tract, and (3) the efficacy of the microcapsule product. The results of these perfusion studies suggest that urea and creatinine can be removed from the GI tract via ingestible adsorbents. In addition, the model may be useful in investigating suspect uremic toxins, e.g., guanidinosuccinic acid (GSA). The reduction of blood urea nitrogen levels in the dog model when the animal was fed the microcapsule product was limited by the capacity of the zirconium phosphate to bind ammonium ion. Preliminary clinical studies with the microcapsule product indicate that it may be of potential adjunctive therapy in patients suffering from chronic renal failure.
 ...
PMID:An orally administered microcapsule system for treating chronic renal failure patients. 652 33

After the urine was treated with urease, lyophilized, and trimethylsilylated, it was examined for metabolic profiles in Dalmatian dogs and Shetland sheepdogs by gas chromatography-mass spectrometry (GC/MS), which simultaneously analyzes organic acids, amino acids, sugars, sugar alcohols, purine and pyrimidine bases, and nucleosides. The profiles were compared with those from human specimens. As clarified in past studies, Dalmatian dogs showed an extreme decrease in allantoin, which is the final product of purine metabolism in the canine of other species, and a marked detection of uric acid peak. This finding suggests that purine metabolism in Dalmatian dogs is different from that in the other species. Only two Shetland sheepdogs, whose mother had chronic renal failure, showed a marked excretion of uric acid, as in Dalmatian dogs. In addition, some Dalmatian dogs, who were maintained on a protein-restricted diet, showed a little excretion of uric acid. A large amount of uric acid is detected in combination with pentose-monosaccharides, hexose-monosaccharides and sugar alcohols in neonatal human urine in comparison with the present dog samples. A marked difference between the canine and the humans is that phenylacetylglycine, which is derived from the aromatic amino acid phenylalanine, is excreted in the canine urine. Phenylacetylglycine is not detected in the human urine, and there have been no reports of its excretion in canine urine.
 ...
PMID:Gas chromatography-mass spectrometric studies of canine urinary metabolism. 749 34

The prevalence of Helicobacter pylori (H. pylori) was investigated in 164 consecutive patients with different degrees of renal function; group I (normal renal function) n = 84, group II (chronic renal failure, CLCR > or = 5 < 90 ml/min) n = 45, group III (haemodialysis therapy) n = 35, to test the hypothesis that the resulting different concentrations of urea in the gastric juice would have an influence on the colonization of the gastric mucosa by these urea-splitting bacteria. As every individual method for the detection of H. pylori shows disadvantages, the results of the detection methods used (urease test, Warthin-Starry stain, bacterial cultivation, direct examination of the processed sample by phase-contrast microscopy) were combined in a cumulative evaluation. These calculated cumulative indices for the antrum and corpus showed no statistically significant differences between the studied groups. The prevalence of H. pylori ranged from 34 to 54%. The histopathological findings were similar in all groups. In spite of the fact that patients with renal dysfunction had significantly higher levels of serum gastrin (P < 0.05), there was no influence on the gastric juice pH value. The relationship between the cumulative index and ammonia concentration in gastric juice was found to be linear (P < 0.05). The higher urea levels in the blood and gastric juice of patients with renal failure do not seem to be a risk factor for infection with H. pylori.
 ...
PMID:Prevalence of Helicobacter pylori in patients with chronic renal failure. 839 2

The diagnostic accuracy of gastric urease activity for Helicobacter pylori (HP) infection were studied in 98 patients with peptic ulcer, gastritis and chronic renal failure. Gastric aspirates were analyzed for urea nitrogen and ammonia. Urease activity was calculated as the ratio of gastric ammonia to sum of gastric urea nitrogen and ammonia. Gold standard assessments to HP infection were rapid urease test, histology and/or culture. The results showed that the values of urease activity in patients with HP infection higher than that in patients without HP infection. This were further assessed by eradication of HP. Sixteen patients with HP infection were treated with DeNol 330 mg/day for 4 weeks. HP was eradicated in 8/16 patients. In those cases urease activity reduced (P < 0.05). If taken 0.31 as the cut-off index of urease activity to diagnosis HP infection, the sensitivity, specificity and accuracy were 95%, 84%, 93% respectively and were not affected by blood urea nitrogen.
 ...
PMID:[The diagnostic accuracy of gastric urease activity for Helicobacter pylori]. 840 18

The objective of the study was to evaluate the prevalence of Helicobacter pylori in patients with different degrees of renal function. Two hundred and twenty consecutive patients requiring gastroscopy for upper intestinal symptoms were enrolled in the study: group I (normal renal function, n = 127), group II (chronic renal failure, creatinine clearance > 5 < 90 ml/min, n = 59), and group III (hemodialysis therapy, n = 34). On endoscopy, biopsy specimens were taken for analysis of H. pylori infection by urease test and histology. The prevalence of H. pylori in patients with renal dysfunction proved to be significantly lower than that in patients with normal renal function (22.6% vs 37%, P < 0.05). The incidence of ulcer disease in patients with normal renal function was higher than that in uremic patients (14.2% vs 10.8%, not significant). These findings indicate that uremic patients seem to be partly protected against H. pylori infection.
 ...
PMID:Significantly lower prevalence of Helicobacter pylori in uremic patients than in patients with normal renal function. 857 29

During the past few years, considerable attention has been given to the impact of nutrition on kidney disease. The question arises of whether the effect of a moderate dietary protein restriction could be reinforced by enrichment of the diet with fermentable carbohydrates. Feeding fermentable carbohydrates may stimulate the extrarenal route of nitrogen (N) excretion through the fecal route. Such an effect has been reported in several species, including healthy humans and patients with chronic renal failure (CRF). Furthermore, studies of these subjects show that the greater fecal N excretion during the fermentable carbohydrate supplementation period was accompanied by a significant decrease in plasma urea concentration. In animal models of experimental renal failure, the consumption of diets containing fermentable carbohydrates results in a greater rate of urea N transfer from blood to the cecal lumen, where it is hydrolyzed by bacterial urease before subsequent microflora metabolism and proliferation. Therefore, this results in a greater fecal N excretion, coupled with a reduction in urinary N excretion and plasma urea concentration. Because elevated concentrations of serum urea N have been associated with adverse clinical symptoms of CRF, these results suggest a possible usefulness of combining fermentable carbohydrates with a low-protein diet to increase N excretion through the fecal route. Further investigations in this population of patients of whether fermentable carbohydrates in the diet may be beneficial in delaying or treating the symptoms and chronic complications of CRF will certainly emerge in the future. This should be realized without adversely affecting nutritional status and, as far as possible, by optimizing protein intake for the patients without being detrimental to renal function.
 ...
PMID:Role of fermentable carbohydrate supplements with a low-protein diet in the course of chronic renal failure: experimental bases. 1019 3


1 2 Next >>