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)

Enzyme-catalyzed polymer transformation with electrochemical ac impedance detection has been employed for the measurement of urea and creatinine in serum samples. A polymer, based on poly(methylvinyl ether)/maleic anhydride modified by esterification with n-octanol, which is stable at pH 7.4 and which is transformed rapidly in response to alkaline pH changes, was linked to enzymatic reactions between urease and urea or creatinine deiminase and creatinine to produce a disposable sensor system. The polymer was screen-printed onto interdigitated screen-printed carbon electrodes and the electrodes overlaid with absorbent pads containing the relevant enzyme. Application of serum samples, "spiked" with either urea or creatinine, resulted in rapid polymer transformation, and resultant changes in the capacitance of the polymer-coated electrodes were analyte-concentration dependent. Additional information on the mechanisms of polymer transformation was obtained from dynamic quartz crystal microbalance measurements.
 ...
PMID:Electrochemical sensor for measurement of urea and creatinine in serum based on ac impedance measurement of enzyme-catalyzed polymer transformation. 1036 94

A simplified method for organic acidemia screening using GC/MS, the urease/direct method, is now available. To establish a practical screening system for organic acidemias, we studied the usefulness of dried urine filter paper (filter paper urine) and the application of a personal computer-based system of automated metabolic profiling and interpretation (automated system) that we earlier developed. In a comparison of filter paper urine with liquid urine, creatinine levels ranging from 4.6 to 122.5 mg/dl, showed an excellent correlation (r=0.9554), when the volumes of blotted urine and distilled water soaked were the same. Recovery of all 17 compounds except for citrate was similar between liquid and filter paper urine. CV values of 22 compounds tested ranged from 5.5 to 22.4% in the liquid urine, and from 7.7 to 29.8% in the filter paper urine. The CV values in stable isotope dilution analysis were much smaller in all nine compounds tested. As to the stability of compounds, the percentage changes to values at day 0 were within about +/-25% on day 28. We compiled GC/MS data, including methylene unit values, quantifying and confirming ions of 163 different organic acids and others, to use the automated system. We analyzed specimens from 55 patients with 17 different metabolic disorders. In 54 of the 55 specimens, the correct diagnosis was successfully indicated. Neonatal mass screening for organic acidemias warrants ongoing attention using this simplified method and filter paper urine.
 ...
PMID:Simplified screening for organic acidemia using GC/MS and dried urine filter paper: a study on neonatal mass screening. 1078 35

Homocystinuria types I, II and III are characterized by different etiologies, biochemical abnormalities and therapeutic measures. For this reason, differential diagnosis is critical for effective treatment. We describe here a rapid and simple procedure for establishing a differential diagnosis of the three types of homocystinuria by analyzing the urine of patients. This procedure, which consists of urease treatment, stable isotope dilution and GC-MS, enables a simultaneous quantification of methionine, homocystine, cystine, methylmalonate, orotate, uracil and creatinine. Analysis with this procedure showed that a case of homocystinuria type I, who progressed into transient megaloblastic anemia, secondarily excreted an increased concentration of orotate, which normalized after treatment with folate and vitamin B12. Therefore, the present diagnostic procedure not only enables rapid differential diagnosis of homocystinuria, but also should prove useful for monitoring the disease state and understanding the nutritional condition and therapeutic state of patients, which in turn can be used to evaluate the efficacy of treatment.
 ...
PMID:Differential diagnosis of homocystinuria by urease treatment, isotope dilution and gas chromatography-mass spectrometry. 1089 84

This review will be concerned primarily with a practical yet comprehensive diagnostic procedure for the diagnosis or even mass screening of a variety of metabolic disorders. This rapid, highly sensitive procedure offers possibilities for clinical chemistry laboratories to extend their diagnostic capacity to new areas of metabolic disorders. The diagnostic procedure consists of the use of urine or filter paper urine, preincubation of urine with urease, stable isotope dilution, and gas chromatography-mass spectrometry. Sample preparation from urine or filter paper urine, creatinine determination, stable isotope-labeled compounds used, and GC-MS measurement conditions are described. Not only organic acids or polar ones but also amino acids, sugars, polyols, purines, pyrimidines and other compounds are simultaneously analyzed and quantified. In this review, a pilot study for screening of 22 target diseases in newborns we are conducting in Japan is described. A neonate with presymptomatic propionic acidemia was detected among 10,000 neonates in the pilot study. The metabolic profiles of patients with ornithine carbamoyl transferase deficiency, fructose-1,6-bisphosphatase deficiency or succinic semialdehyde dehydrogenase deficiency obtained by this method are presented as examples. They were compared to those obtained by the conventional solvent extraction methods or by the tandem mass spectrometric method currently done with dried filter blood spots. The highly sensitive, specific and comprehensive features of our procedure are also demonstrated by its use in establishing the chemical diagnosis of pyrimidine degradation defects in order to prevent side effects of pyrimidine analogs such as 5-flurouracil, and the differential diagnosis of three types of homocystinuria, orotic aciduria, uraciluria and other urea cycle disorders. Evaluation of the effects of liver transplantation or nutritional conditions such as folate deficiency in patients with inborn errors of metabolism is also described.
 ...
PMID:Diagnosis of inborn errors of metabolism using filter paper urine, urease treatment, isotope dilution and gas chromatography-mass spectrometry. 1148 33

Inborn errors of pyrimidine degradation, dihydropyrimidine dehydrogenase deficiency and dihydropyrimidinase deficiency, are less rare than has generally been assumed. Many asymptomatic cases have been reported, and in patients with symptoms, the clinical abnormalities are variable and nonspecific. Withdrawal of pyrimidine analogues such as 5-fluorouracil (5FU), a commonly used anticancer drug, from the cancer chemotherapy regimens of patients with pyrimidine degradation deficiencies, however, is critical because 5FU is degraded in vivo by pyrimidine-degradative enzymes. Patients with these deficiencies suffer from severe neurotoxicity, sometimes leading to death, following administration of 5FU, and even otherwise asymptomatic homozygotes or heterozygotes may develop severe clinical symptoms upon administration of such medication. Therefore, a rapid and specific method for identifying cancer patients with these enzyme deficiencies prior to treatment with 5FU is critical. To address this problem, we established methods for highly sensitive yet specific determinations of thymine, uracil, dihydrothymine, dihydrouracil, orotate and creatinine simultaneously in 0.1-ml liquid urine or filter-paper urine. This method involves stable isotope dilution, a simplified urease treatment previously described and gas chromatography-mass spectrometry without prior fractionation. The high recovery and low C.V. values were obtained and healthy control values were also determined for these metabolites. Using artificially prepared urine specimens simulating these disorders. the chemical diagnosis can be made clearly, and no further analysis appears to be required for differential chemical diagnosis.
 ...
PMID:Simple gas chromatographic-mass spectrometric procedure for diagnosing pyrimidine degradation defects for prevention of severe anticancer side effects. 1148 36

We describe the rapid and sensitive detection of 4-hydroxybutyric acid, which is a marker compound for succinic semialdehyde dehydrogenase (SSADH) deficiency. Urinary 4-hydroxybutyric acid and 3,4-dihydroxybutyric acid were targeted, quantified by gas chromatography-mass spectrometry after simplified urease digestion in which lactone formation from gamma-hydroxy acids is minimized. The recovery of 4-hydroxybutyric acid using this method was over 93%. 2,2-Dimethylsuccinic acid was used as an internal standard. The detection limit of this method was 1 nmol ml(-1) for both 4-hydroxybutyric acid and 3,4-dihydroxybutyric acid. The urinary concentrations of 4-hydroxybutyric acid and of 3,4-dihydroxybutyric acid from the patient with an SSADH deficiency were 880-3628 mmol mol(-1) creatinine (control; 3.3+/-3.3 mmol mol(-1) creatinine) and 810-1366 mmol mol(-1) creatinine (control; 67.4+/-56.2 mmol mol(-1) creatinine), respectively. The simplified urease digestion of urine is very useful for quantifying 4-hydroxybutyric acid and its related compounds in patients with 4-hydroxybutyric aciduria.
 ...
PMID:Rapid and sensitive detection of urinary 4-hydroxybutyric acid and its related compounds by gas chromatography-mass spectrometry in a patient with succinic semialdehyde dehydrogenase deficiency. 1212 25

Two cases of benign methylmalonic aciduria (MMAuria) were found among 9780 neonatal screenings using the previously described screening method consisting of urease digestion, ethanol deproteinization and gas chromatography-mass spectrometry. Combining this screening method with the stable isotope dilution technique showed very specific and sensitive measurements of methylmalonic acid in urine. The concentrations of urinary methylmalonic acid were measured at several ages. The levels of urinary methylmalonic acid in two patients varied from 0.27 to 3.04 mol/mol creatinine (control<0.01 mol/mol creatinine). Methylcitrate and homocystine were not increased in the patient's urine or blood. Blood propionylcarnitine was also at normal levels. The urinary methylmalonate excretions were decreased to the levels of about 50% of the start point after vitamin B12 treatment in one patient, but the other patient showed no change. No clinical abnormalities were observed during these periods.
 ...
PMID:Two cases of benign methylmalonic aciduria detected during a pilot study of neonatal urine screening. 1212 26

Urea recycling in ruminants has been studied extensively in the past, but the mechanisms regulating the amount of urea recycled or excreted remain obscure. To elucidate the role of urea transporters (UT) in N recycling, nine Dorset-Finn ewe lambs (20.8 +/- 0.8 kg) were fed diets containing 15.5, 28.4, and 41.3 g of N/kg of DM for 25 d. Nitrogen balance and urea N kinetics were measured during the last 3 d of the period. Animals were then slaughtered and mucosa samples from the rumen, duodenum, ileum, and cecum, as well as kidney medulla and liver, were collected. Increasing N intake tended to increase N balance quadratically (1.5, 5.1, and 4.4 +/- 0.86 g of N/d, P < 0.09), and linearly increased urinary N excretion (2.4, 10, and 16.5 +/- 0.86 g N/d, P < 0.001) and plasma urea N concentration (4.3, 20.3, and 28.4 +/- 2.62 mg of urea N/dL, P < 0.001), but did not affect fecal N excretion (5.0 +/- 0.5 g of N/d; P < 0.94). Urea N production (2.4, 11.8, and 19.2 +/- 0.83 g of N/d; P < 0.001) and urinary urea N excretion (0.7, 7.0, and 13.4 +/- 0.73 g N/d; P < 0.001) increased linearly with N intake, as well as with the urea N recycled to the gastrointestinal tract (1.8, 4.8, and 5.8 +/- 0.40 g of N/d, P < 0.001). No changes due to N intake were observed for creatinine excretion (518 +/- 82.4 mg/d; P < 0.69) and clearance (46 +/- 10.7 mL/min; P < 0.56), but urea N clearance increased linearly with N intake (14.9, 24.4, and 34.9 +/- 5.9 mL/min; P < 0.04). Urea N reabsorption by the kidney tended to decrease (66.3, 38.5, 29.1 +/- 12.6%; P < 0.06) with increasing N content of the diet. Increasing the level of N intake increased linearly the weight of the liver as a proportion of BW (1.73, 1.88, and 2.22 +/- 0.15%, P < 0.03) but only tended to increase the weight of the kidneys (0.36, 0.37, and 0.50 +/- 0.05%, P < 0.08). Urea transporter B was present in all the tissues analyzed, but UT-A was detected only in kidney medulla, liver, and duodenum. Among animals on the three diets, no differences (P > 0.10) in UT abundance, quantified by densitometry, were found. Ruminal-wall urease activity decreased linearly (P < 0.02) with increasing level of N intake. Urease activity in duodenal, ileal, and cecal mucosa did not differ from zero (P > 0.10) in lambs on the high-protein diet. In the present experiment, urea transporter abundance in the kidney medulla and the gastrointestinal tract did not reflect the increase in urea-N reabsorption by the kidney and transferred into the gut.
 ...
PMID:Effect of nitrogen intake on nitrogen recycling and urea transporter abundance in lambs. 1508 Mar 38

An alginate microcapsule was developed that contains three enzymes (urease, uricase, and creatininase) capable of effectively degrading urea, uric acid, and creatinine, which are elevated to pathologic levels in patients with kidney failure. The capsules were evaluated in vitro and in vivo in a rodent model and evidenced considerable potential as a possible adjunctive therapy in the treatment of ESRD. In vitro, 5 mL of the capsules incorporating a quantity of enzymes in the mg range effectively degraded all the uric acid, 97% of the urea, and 70% of the creatinine within 24 hours in a 100 mL test solution simulating the concentration of these solutes in uremic plasma. Enzyme degradation of urea followed Michaelis-Menten kinetics, and the Lineweaver-Burk plots for both encapsulated enzymes and unencapsulated control animals were superimposable, indicating that mass transfer through the capsules was not rate limiting in the degradation process. A chemically induced acute renal failure model in the rat was used to evaluate the ability of encapsulated enzymes, along with an oral sorbent (ion exchange resin), to degrade uremic toxins in vivo. Encapsulated enzyme therapy decreased the severity of azotemia by as much as 70%. Preliminary scale up calculations indicated that oral delivery to humans would involve a practical and manageable quantity of enzymes. This is the first study using a combination of enzymes in a single delivery vehicle to degrade multiple uremic toxins.
 ...
PMID:Degradation of low molecular weight uremic solutes by oral delivery of encapsulated enzymes. 1517 78

The objective of this study was to determine the specific reference values for urinary calcium/creatinine (UCA/Cr) (mg/mg) in healthy breast-fed newborns, and to evaluate the relationship between UCa/Cr, urinary sodium/creatinine (UNa/Cr), urinary potassium/creatinine (UK/Cr) and UNa/UK ratios in the same group. A total of 88 infants aged between 0-28 days were enrolled in this study. They were divided into two age groups as follows: Group I: < or = 7 days of age; Group 2 infants aged between 8-28 days. Non-fasting spot urine was analyzed for Ca, Na, K and Cr. Significant differences were observed between the two groups in terms of UCa/Cr (0.11+/-0.10 vs 0.27+/-0.23, p<0.001), UNa/Cr (1.29+/-1.63 vs 5.5+/-4.83, p<0.001), and UK/Cr (0.94+/-0.99 vs 2.82+/-2.3, p<0.001). The data showed positive correlation between UCa/Cr and age (r=0.38, p<0.001) as well as between age and UNa/Cr ratio (r=0.68, p=0.0001) and between age and UK/Cr ratio (r=0.57, p<0.0001). Additionally, there was a positive correlation between UNa/UK and age (r=0.40, p=0.001). The UCa/Cr ratio positively correlated with UNa/Cr whereas no correlation was found between UCa/Cr and UNa/Uk ratio. Our data suggest that the healthy neonates differ from the hypercalciuric patients by exhibiting a linear correlation between Na/K and UCa/Cr. As the normal values of UCa/Cr, UNa/Cr, UK/Cr, UNa/UK ratios in the early neonatal period differ from those in the late neonatal period, these differences should be taken into consideration when assessing urinary excretion of these parameters for diagnostic purposes in the early and late newborn periods.
 ...
PMID:The relationship between urinary calcium, sodium, and potassium excretion in full-term healthy newborns. 1588 28


<< Previous 1 2 3 4 5 Next >>