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Results for “URATE OXIDASE”

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At least 685 records · Page 38Linked to original sources
PubMed1987

Does morphine enhance the release of 5-hydroxytryptamine in the rat spinal cord? An in vivo differential pulse voltammetry study.

Differential pulse voltammetry used in combination with an electrochemically treated carbon fiber electrode allowed the detection of 5-hydroxyindoles (5-HI) in the dorsal horn of the urethane-anesthetized rat. Voltammograms were recorded every 3 min for up to 4 h. One component of the signal, peak 3, corresponding to 5-HI and uric acid was first identified separately in vitro as well as in vivo, and then further examined by means of systemic L- and D-trytophan administration and by local application of uricase, respectively. It was found that the height of peak 3 was unaffected by systemic morphine. Even following pretreatment with probenecid, the height of peak 3 was increased only 8.6-13.7% over that with saline, by morphine given either intraperitoneally or intracerebrally into the nucleus raphe magnus. However, these increments of peak 3 were not statistically significant. These findings suggest that the serotonin descending system is unlikely to play an important role in morphine analgesia.

Animals↗
PubMed1975

An alternative method for the determination of uric acid in serum.

A novel fluorometric method for the determination of uric acid based on the coupled reactions of uric acid with uricase and peroxidase to form highly fluorescent 2,2'dihydroxy-3,3'-dimethoxy-biphenyl-5,5'-diacetic acid is described. The calibration curve was constructed from a series of standard uric acid solutions vs. the corresponding relative fluorescence. It was linear up to 15 mg/dl (0.9 mmol/l). The serum or plasma samples must be deproteinated with (absolute) ethanol before assay and its uric acid content can be obtained from the calibration curve. This method is rather simple, having good precision and accuracy. High level ascorbic acid in the sample falsely elevates uric acid concentration. Comparison of the results obtained on the patient sera with a colorimetric phosphotungstate method and a standard enzymatic spectrophotometric method gave coefficients of correlation of 0.908 and 0.986, respectively.

Ascorbic Acid↗
PubMed1979

Evaluation of three clinical chemical routine methods for the determination of serum uric acid, by mass fragmentography.

A mass fragmentographic method for assay of serum uric acid was developed and used as a reference method to evaluate the accuracy of different routine methods used in clinical chemistry. [1,3-15N2]Uric acid was added to the serum sample and the mixture was subjected to ion-exchange chromatography. After conversion to the tetra-trimethylsilyl derivative the purified mixture was analyzed by combined gas chromatography-mass spectrometry using a multiple ion detector. Within-series imprecision of the reference method as calculated by means of relative standard deviation was 0.6%. The small difference between calculated and found value obtained in different recovery experiments could be explained by this degree of imprecision. In a comparison between results obtained with the reference method and different routine methods, a significant difference was observed only when using an uricase-oxygen consumption method.

Catalase↗
PubMed1980

Methodological principles in the enzymatic determination of substrates illustrated by the measurement of uric acid.

The enzymatic method of Haeckel for the determination of uric acid in serum has been used to compare three different kinetic approaches with the corresponding equilibrium (end-point) procedure. The kinetic methods were: measurement of the difference in absorbance between two pre-selected fixed instants during the course of the reaction under first-order conditions; measurement of the initial rate of reaction at substrate concentrations sufficiently low for first-order kinetics to apply, and determination of initial rate with substrate concentrations approximating to, or greater than, the Michaelis constant (pseudo-zero order kinetics). In the third method results were obtained by solving the Michaelis-Menten equation. The results emphasise the superiority of the two-point kinetic approach, which is apparent even when the timed absorbance values are obtained from an analogue signal displayed on a recorder chart. Conditions are described for the determination or uric acid in serum according to this principle.

Clinical Enzyme Tests↗
PubMed1980

Determination of uric acid with uricase and peroxidase.

A reliable method for the determination of uric acid in plasma or serum is described. The hydrogen peroxidase developed in the uricase reaction is used, together with peroxidase, for the coupling of sulphonated dichlorophenol and 4-aminoantipyine to a red dye. The difference in absorbance at 515 nm before and after addition of uricase is measured. Of the components tested for interference some gave rise to falsely lowered values. Reagents are cheap and the high molecular absorption coefficient of the red dye permits the use of small sample volumes.

Humans↗
PubMed1987

Biosensor for lactate determination in biological fluids. 2. Interference studies.

The selectivity of a yeast lactate biosensor with immobilized cells of aerobic yeast Hansenula anomala was studied. Reducing substances potentially present in blood plasma influenced both enzyme and yeast biosensors in the same way; the highest positive error was observed in the case of uric acid. With respect to the metabolic activity of the yeast cells the biosensor was absolutely specific for lactate during the first two weeks; later on the biosensor responded slightly to some other metabolites, especially some sugars and amino acids. Glucose could cause the highest degree of interference, its effect was however completely eliminated by adding sodium fluoride to the reaction solution. The concentration of other metabolites present in blood plasma is not great enough to call a significant positive error. The results thus support the general use of the yeast lactate biosensor for lactate determination in biological material.

Humans↗
PubMed1992

Influence of triglycerides and urate on methods for determination of fructosamine.

The original fructosamine assay, based on reduction of NBT, has been modified and marketed as a kit. The development includes addition of detergents, uricase, change of the buffer and NBT concentrations, and use of a new calibrator. We report the effects of these changes on the measured values of fructosamine in lipemic and uricemic sera. A secondary calibrator produced from pooled serum and stabilized by removal of glucose was used to calibrate the original fructosamine assay and enhance transferability of results. There was no correlation between the difference between the results obtained by the two procedures and the concentration of urate or triglycerides. The development of colour was faster with the original method. It is suggested that measurements of fructosamine by either method are practically equivalent. However, the use of polylysine as a calibrator is advantageous. It is suggested that the generic term S-Glycated proteins is used for the measurand rather than S-Fructosamine which in effect has become a commercial term.

Fructosamine↗