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At least 1,423 records · Page 79Linked to original sources
PubMed2003

Cutaneous microdialysis of uric acid level in the dermis: modification of in vitro recovery.

Cutaneous microdialysis is a new tool for direct sampling and real-time monitoring in dermatological research. However, its use in general laboratory practice poses several problems, one of which is determination of the relative recovery of the target material. Uric acid, one of the major antioxidants in the skin, was analysed using cutaneous microdialysis in 11 healthy subjects. Two methods for in vitro recovery were adopted, one in which a standard solution of uric acid was used and another in which serum was used. Although differences between the two methods were found, it is suggested that establishing the in vitro recovery using serum might be a simple approach for microdialysis.

Adult↗
PubMed1986

Reduced susceptibility to lipid peroxidation in cold ischemic rabbit kidneys after addition of desferrioxamine, mannitol, or uric acid to the flush solution.

Rabbit kidneys were stored for 24 hr at 0 degree C after single passage arterial flush with 30 ml of cold isotonic 0.9% sodium chloride (saline) solution alone or saline to which was added 12, 30, or 60 mM desferrioxamine, 1 or 3 mM uric acid, or 100 mM mannitol. They were then subjected to in vitro biochemical assay for evidence of free radical damage immediately after storage. Results were compared to those obtained with fresh, unstored kidneys. Levels of Schiff base fluorescence, diene conjugates, and thiobarbituric acid-reactive material were each significantly elevated in kidneys stored for 24 hr after flush with saline alone. These levels were in turn each significantly reduced by the addition of 60 mM desferrioxamine, 3 mM uric acid, and 100 mM mannitol to the flush solution. Likewise, glutathione redox activity fell in those flushed with saline alone, presumably in line with increased lipid peroxidation, but was restored to control levels by inclusion of the three scavenging agents.

Animals↗
PubMed1983

Preliminary results of glycosminoglycans excretion in normal and stone forming subjects: relationship with uric acid excretion.

In calcium lithiasis, pathogenesis inhibitors have a significant role to play which permits raising of the upper metastability limit in the urine, thus reducing the crystallization processes. The aim of this work is to evaluate glycosaminoglycans excretion and concentration in a group of patients with idiopathic calcium lithiasis, and in a control group for detecting possible differences between the 2 groups. Analysis of our results shows that no significant differences exist between the 24-hour average excretion of glycosaminoglycans in normal and stone forming subjects, but there was a significant difference in the mean concentration values between the 2 groups, either as whole or when separately considered with respect to normal or increased uric acid excretion. Particularly interesting was the correlation study between glycosaminoglycans and uric acid which shows a linear relationship with a positive slope in all groups but in stone formers with hyperuricosuria.

Adult↗
PubMed2004

Independent association of uric acid levels with peripheral arterial disease in Taiwanese patients with Type 2 diabetes.

AIMS: Hyperuricaemia may be a risk factor for atherosclerotic disease. Its association with peripheral arterial disease (PAD) has not been studied in Taiwanese patients with Type 2 diabetes. METHODS: Uric acid (UA) levels and PAD were evaluated in 508 Taiwanese outpatients with Type 2 diabetes (210 men, 298 women; mean age +/- sd, 63.8 +/- 10.6 years). PAD was diagnosed when the ankle-brachial index was < 0.9. Patients with an ankle-brachial index of > or = 1.3 were excluded because of possible medial arterial calcification. Potential confounding variables with P < 0.10 were adjusted for in multivariate analyses. RESULTS: In univariate analyses, UA levels were higher in patients with PAD than in those without PAD (345.0 +/- 95.2 vs. 309.3 +/- 89.2 micromol/l; P < 0.0005). Prevalences of PAD for quintiles of UA levels were 6.8, 8.9, 10.2, 13.1 and 16.5%, respectively (P-trend < 0.05). With UA level as a continuous variable, the multivariate-adjusted odds ratio (95% confidence interval) for PAD was 1.005 (1.001-1.008) (P < 0.01). The optimal cut-off point for UA as determined by the receiver operating characteristic curve was 264.7 micromol/l. The sensitivity and specificity at this cut-off point was 82.6 and 33.3%, respectively. The area under curve was 0.60 (95% confidence interval: 0.53-0.68). The multivariate-adjusted odds ratio for PAD for UA above this level was 2.736 (1.239-6.043) (P < 0.05). The results after excluding 56 cases using diuretics were similar. CONCLUSIONS: Elevated uric acid level is a significant and independent risk factor for PAD in Taiwanese patients with Type 2 diabetes.

Aged↗
PubMed1987

The association of the ratio of waist to hip girth with blood pressure, serum cholesterol and serum uric acid in children and youths aged 6-17 years.

To determine whether the association of the ratio of waist to hip girth with cardiovascular risk factors exists in prepubertal children and pubertal youths, the ratio was related to blood pressure, serum cholesterol and serum uric acid levels in children and youths aged 6-17 yr in the Health Examination Survey. In these samples drawn from the United States population, the ratio declined with increasing age. Boys had consistently higher ratios than girls. Black-white differences were inconsistent. The ratio was lower in girls whose menstrual periods had started at each age after 10. The ratio was significantly associated with systolic blood pressure in youths and with diastolic blood pressure in children independent of confounders. It was also significantly associated with serum uric acid but not serum cholesterol independent of confounders among youths. Longitudinal studies are needed of greater abdominal relative to lower body fat deposits in children and youths and risk of cardiovascular disease in adulthood.

Abdomen↗
PubMed2002

Manipulation of plasma uric acid in broiler chicks and its effect on leukocyte oxidative activity.

Birds have high metabolic rates, body temperatures, and plasma glucose concentrations yet physiologically age at a rate slower than comparably sized mammals. These studies were designed to test the hypothesis that the antioxidant uric acid protects birds against oxidative stress. Mixed sex broiler chicks (3 wk old) were fed diets supplemented or not with purines (0.6 mol hypoxanthine or inosine). Study 1 consisted of 18 female Cobb x Cobb broilers that were fed purines for 7 days, whereas study 2 consisted of 12 males in a 21-day trial. Study 3 involved 30 mixed sex broilers that were fed 40 or 50 mg allopurinol/kg body mass (BM) for 21 days, a drug that lowers plasma uric acid (PUA). PUA and leukocyte oxidative activity (LOA) were determined weekly for all studies. For study 2, pectoralis major shear force, relative kidney and liver sizes (RKS and RLS), and plasma glucose concentrations were also determined. In study 1, PUA concentration was increased three- and twofold (P < 0.001) in birds fed inosine or hypoxanthine, respectively, compared with control birds. LOA of birds supplemented with inosine was lower (P < 0.05) than that of control or hypoxanthine birds. In study 2, PUA concentrations were increased fivefold (P < 0.001) in birds fed inosine and twofold (P < 0.001) in birds fed hypoxanthine compared with control birds at day 21. RKS (g/kg BM) was greater (P < 0.001) for chicks fed purine diets compared with control chicks. Muscle shear value was lower (P < 0.05) in chicks fed purine diets. PUA concentration was decreased (P < 0.001) in birds consuming allopurinol diets, whereas LOA was increased (P < 0.01) in study 3. These studies show that PUA concentrations can be related to oxidative stress in birds, which can be linked to tissue aging.

Animals↗
PubMedDate not supplied

[A comparative study of the sodium, potassium, urea, creatinine, and uric acid concentrations in the human amniotic fluid between weeks 15-20 and 38-42].

UNLABELLED: The amniotic fluid physiology is a dynamic process involving maternal and fetal compartments and depends on gestational age. PURPOSE: To analyze the concentration of sodium, potassium, urea, creatinine, and uric acid in the amniotic fluid of normal pregnant women in the second and third trimester. Also, to evaluate the influence of maternal age, race, parity, and fetal sex on those elements. METHOD: Fifty samples obtained by genetic amniocentesis (15-20 weeks, group I) and fifty obtained by elective cesarean section (38-42 weeks, group II) were analyzed. According to the variables we used the following statistical tests: Analysis of variance; Test t Student: Chi-square test; Mann-Whitney test (a 0.05 pounds). RESULTS: In group II, urea, creatinine and uric acid levels were significantly higher than in group I. The sodium level was significantly lower in group II compared with group I. The potassium concentration did not show any significant difference in both groups. There was no significant interference of maternal age, race, parity and fetal sex in any of the five studied variables. CONCLUSION: These findings were emphasized for prenatal diagnosis purposes and analysis of renal function. The authors suggest future comparisons of obtained "normal" data with pathological situations.

Amniocentesis↗
PubMed2005

Serum uric acid levels and the risk of Parkinson disease.

In a prospective population-based cohort study among 4,695 participants aged 55 years and older, with repeated in-person examination and on average 9.4 years of follow-up, we observed that higher serum levels of uric acid were associated with a significantly decreased risk of Parkinson disease (adjusted hazard ratio per standard deviation increase 0.71 [95% confidence interval 0.51-0.98]), with evidence for a dose-effect relationship (p value for trend over quartiles 0.040). Our findings support the hypothesis that oxidative stress contributes to the risk of Parkinson disease and suggest a potential protective effect of the natural antioxidant and free radical scavenger uric acid.

Aged↗
PubMed1977

Uric acid calculi: results of conservative treatment.

A total of 140 patients with uric acid diathesis have been treated for the last five years with a standardized mixture of sodium and potassium citrate and citric acid (Uralyt U) together with forced fluid intake and, if necessary, the addition of allopurinol. The results have been encouraging; 80 per cent of the patients showed complete dissolution of the stones and relief of symptoms.

Citrates↗
PubMed1979

Investigation of the enzymic and electrochemical oxidation of uric acid derivatives.

The electrochemical oxidation of a number of N-methylated uric acids at the pyrolytic graphite and gold electrodes has been compared to their enzymic oxidation with type VIII peroxidase and H2O2. Spectral, electroanalytical and kinetic evidence supports the conclusion that for all compounds the electrochemical and enzymic reactions proceed by identical mechanisms.

Electrochemistry↗
PubMed1996

Allopurinol, an inhibitor of xanthine oxidase, reduces uric acid levels and modifies the signs associated with copper deficiency in rats fed fructose.

This study was designed to focus on the potential stress that xanthine oxidase could produce in copper-deficient rats fed fructose. Fructose consumption results in an excess production of uric acid due to an increased degradation of nucleotides. The enzyme xanthine oxidase catalyzes the oxidation of both hypoxanthine and xanthine. During the oxidation process free radicals are generated, which in turn, induce lipid peroxidation and premature death. Allopurinol -- a competitive inhibitor of xanthine oxidase -- could alleviate the combined effects of fructose feeding and copper deficiency. Twenty-five male rats were fed for 4 weeks from weaning a copper-deficient or adequate diet containing fructose. Twelve rats were given a daily oral dose of 5 mg allopurinol/100 g b.wt. Two copper-deficient rats that were not treated with allopurinol died prematurely during the fourth week of the study. No mortality occurred in the group of copper-deficient rats that had been treated with allopurinol. Anemia was alleviated by allopurinol, which in turn, could be responsible for improved growth rate. Allopurinol was effective in inhibiting xanthine oxidase activity in vivo as measured by the dramatic reduction of uric acid production. Lipid peroxidation, however, was not affected by allopurinol. It is concluded that the beneficial effects of allopurinol in copper deficiency do not appear to be related to prevention of oxygen radicals, but rather, to the protection against the catabolic destruction of purines, which in turn, increases nucleotide pool.

Allopurinol↗
PubMed1986

Frequent administration of uric acid extends survival of fasting analbuminemic rats under cold environment.

Analbuminemic rats died within 18 h after a rapid decrease of body temperature whereas control Charles River, Wistar, and Sprague Dawley rats survived for 40 h, when the animals were kept at 5 degrees C without food. Five low molecular weight fractions obtained from Sprague Dawley rat sera were administered to analbuminemic rats kept under these conditions. The duration of survival was extended by the administration of two of the fractions. Several characteristics of one of these fractions coincided with those of uric acid, and body temperature of analbuminemic and Sprague Dawley rats increased within 5 min after uric acid administration.

Animals↗
PubMed1991

The effect of diclofenac sodium on urinary concentration of calcium, uric acid and glycosaminoglycans in traumatic paraplegics.

Non-steroidal anti-inflammatory drugs (NSAID) have been shown to decrease calcium excretion in the experimental animal, in human volunteers and in calcium stone formers. Paraplegics tend to be hypercalciuric during the first 2 years after their injury and this is said to be a predisposing factor for stone formation in these patients. The effect of the NSAID diclofenac sodium was studied in 12 traumatic paraplegics who had sustained their injury 1 to 6 months previously; 24-h urine samples collected before and 2 weeks and 4 weeks after oral diclofenac sodium 50 mg tds were analysed for calcium, uric acid, glycosaminoglycans (GAGs) and volume. There were no significant changes in urinary volume, uric acid and GAGs excretion. However, urinary calcium concentration and 24-h calcium excretion decreased significantly following 2 weeks' and 4 weeks' treatment with diclofenac sodium.

Adult↗
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↗
PubMedDate not supplied

Urea, creatinine, uric acid, and phosphate spaces and their relationship to total body water during chronic hemodialysis.

The authors determined total body water (TBW) with tritium in 11 patients on chronic hemodialysis and compared this space to that estimated by 60% of body weight, and removal spaces of urea, creatinine, uric acid, and phosphate (PO4). The latter spaces were determined by dividing the total amount of substance (measured in total dialysate) by pre- minus post-dialysis concentrations. Body water X 0.6 was more than 10% less than the tritium space, and showed a maximal variation of 10 liters, or 24%. The removal space of urea was 80% of the tritium space, but correlated closely with it. The difference between total body water and urea removal space was variable and dependent on fluid excess (edema) in the patients. Creatinine, uric acid, and phosphate removal spaces were highly variable and not correlated to total body water. The authors suggest that actual measured TBW should be used, rather than estimations using BW X 0.6, for V in K X T/V, where K = clearance, T = duration of dialysis, and V = the removal space of urea. Furthermore, one may need to introduce a correction factor for urea removal space over TBW in the equation to allow better quantification of dialysis in edematous patients and during very fast dialyses.

Adult↗
PubMed1990

[Effect of purine-rich nutrients on weight gain, catabolites in blood plasma and the uric acid transport of erythrocytes--a model study in dogs].

In a nutritional tolerance study 36 young dogs were fed over 52 weeks high or low purine diets at an average paired feeding intake of 0.6 and 80 mg purine-N/MJ per day. The high purine diet resulted in a significant decrease of growth rate by -23% (Beagles) and -38% (Dalmatians) and of feed efficiency (-29 and -42%). The fasting levels of allantoin, uric acid and uracil in blood plasma were significantly increased. During the experiment a metabolic adaptation to the high purine diet decreased the plasma concentrations of uric acid, uracil and in part of allantoin. The high purine diet effected a significant increase of Km (2.5-fold) and of Vmax (1.6-fold) of uric transport through the erythrocyte membrane. The results documented disadvantageous effects of high purine nutrition during juvenile development.

Allantoin↗
PubMedDate not supplied

Analytical methods for measuring uric acid in biological samples and food products.

During the last 7 decades, uric acid methodology has kept pace with the introduction of state-of-the-art technology (e.g., spectroscopy, electrochemistry, chromatography) or the discovery of unique chemical processes (e.g., redox, enzymatic). We envision this practice will continue in the future. There never will be a single analytical method applicable for biofluids or foodstuffs. Therefore, it is imperative that the analyst not only understand the advantages and disadvantages of a procedure, but also thoroughly understand its underlying chemical and technological principles. Since many procedures available for analysis of biofluids and foodstuffs rely on identical chemical or technological principles, this report shall review both sample types and the available spectroscopic, electroanalytical, and chromatographic methods.

Animals↗