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A high-performance liquid chromatographic assay for uric acid in excreta and tissue samples has been developed. The method uses a reversed-phase system with a C18-bonded column, it is sensitive, reliable, and rapid, and it yields quantitative recovery of uric acid.
Cocks were fed a protein-free diet supplemented with methionine plus arginine or glutamic acid for 25 days to investigate the effect of these amino acids on fecal and urinary nitrogen excretion. Addition of either methionine plus arginine or glutamic acid did not change the fecal nitrogen excretion. Methionine plus arginine supplementation reduced the urniary nitrogen excretion compared to the protein-free diet, whereas glutamic acid supplementation increased it. The reduced urinary nitrogen excretion resulting from supplementation with methionine plus arginine was mostly accounted for by a reduction in uric acid excretion. In the methionine plus arginine group, free amino acid analysis showed that free glutamine and glutamic acid content significantly decreased in liver while no differences were found in plasma. Since glutamine may play an important role in the formation of uric acid for chickens, the reduced amount of free glutamine and glutamic acid in the liver of cocks fed the diet suplemented with methionine plus arginine might account for the reduced excretion of uric acid, and therefore for the nitrogen sparing action of methionine plus arginine in chickens fed a protein-free diet.
Nibbling has been reported to decrease serum cholesterol under fasting conditions, as well as the incidence of cardiovascular disease. It has been suggested that these effects are partly attributable to reduced concentrations of serum insulin, which are also observed. However, data on the effects of nibbling on serum lipids throughout the day are not available, nor is it known how nibbling affects serum uric acid as a further insulin-related risk factor for cardiovascular disease. We have attempted to address these issues. Seven healthy men consumed identical diets in a randomized crossover design either as three meals daily (control) or as 17 meals daily (nibbling) for 2 weeks. On day 13, serum lipid levels were measured over the course of the day (12 hours) together with the 24-hour urinary excretion of mevalonic acid as an indicator of hepatic cholesterol synthesis. Concentrations of uric acid in serum and 24-hour urinary excretion of uric acid were also determined. Mean (+/- SE) percent treatment differences in day-long total, low-density lipoprotein (LDL), and non-high-density lipoprotein (HDL) cholesterol, and apolipoprotein (apo) B were significant, with lower values on the nibbling diet as compared with the control diet (8.1% +/- 1.6%, P = .002; 12.2% +/- 2.6%, P = .005; 10.1% +/- 1.6%, P < .001; and 9.9% +/- 2.6%, P = .008, respectively). No significant difference was seen in the total to HDL cholesterol ratio or in urinary mevalonic acid excretion.(ABSTRACT TRUNCATED AT 250 WORDS)
Lowering of plasma Mg, P, Na, Cl, uric acid, cholesterol, and creatinine is required in renal failure and other diseases. In this preliminary report, we studied the ability of artificial cells microencapsulated genetically engineered E. coli DH5 cells in lower K, Mg, P, Na, Cl, uric acid, cholestrol, creatinine, and billirubin from plasma in-vitro. Result shows that this novel approach has the ability to significantly lower these metabolites from the plasma in-vitro.
The incidence of some risk factors of ischaemic heart disease (IHD) was investigated in a group of 91 type 2 diabetics. A group of 57 patients who had a myocardial infarction was compared with a control group of 34 diabetics without clinical and electrocardiographic signs of IHD. In the group of diabetics with IHD there was a significantly higher proportion of hypertonic patients (70%), as compared with the control group (47%). The diabetics with an infraction in the case-history had a significantly higher mean age and a longer mean duration of diabetes. There was not a significant difference between the two groups as regards mean values of cholesterol, triacylglycerols, blood sugar, urea, creatinine, proteinuria and cerebrovascular attacks. As to metabolic factors, there were significantly higher mean uric acid values in the whole group with a myocardial infarction in the case-history, whereby this increase was more marked in men with IHD. Regression analysis did not reveal a significant correlation between uric acid values and the serum cholesterol or triacylglycerol levels or the incidence of hypertension. A significant biserial correlation between the presence of myocardial infarction and uric acid serum levels persisted also after elimination of the effect of age and creatinine serum levels. Based on these results and analyses of data in the literature, the authors favour the view that uric acid is rather a marker than true risk factor of atherosclerosis in type 2 diabetics.
During hypoxia ATP degradation to uric acid is increased in animal models and humans. To assess the reliability of an overnight increase in uric acid excretion as a marker of nocturnal hypoxemia, we selected 10 normal volunteers (7 males and 3 females), 29 COPD patients (26 males and 3 females), and 49 subjects with obstructive sleep apnea (OSA) (43 males and 6 females). The patients underwent standard polysomnography, which was repeated in 14 subjects with nasal continuous positive airway pressure (CPAP), and were subdivided into two groups: Group D included desaturating subjects who spent at least 1 h at SaO2 < 90% and 15 min below 85%, and Group ND were nondesaturating subjects. The overnight change in the uric acid:creatinine ratio (delta UA:Cr) was negative in normal subjects (-27.5 +/- 9.1 [mean +/- SD]) and ND groups: -19.7 +/- 14.3 in COPD, -16.1 +/- 13.0 in OSA. In both COPD and OSA Group D, the ratio was usually positive: delta UA:Cr was 17.9 +/- 31.4 in Group D COPD (p < 0.001 versus ND) and 10.1 +/- 30.7 in Group D OSA (p < 0.001 versus ND and versus normal subjects) despite 4 of 15 false negative results in COPD and 8 of 20 in OSA. CPAP effective treatment induced a marked reduction ((p = 0.0024) in delta UA:Cr, leading to a negative value. We conclude that delta UA:Cr seems to be a promising index of significant nocturnal tissue hypoxia, with good specificity but poor sensitivity (about 30% false negative), which might be useful for the long-term follow-up of outpatients on nasal CPAP with a positive ratio at baseline.
The effect of 9 nonsteroidal anti-inflammatory drugs on the renal excretion of uric acid was studied in patients with normal renal function. Diflunisal, Azapropazone and Indomethacin caused an increase and Piroxicam a decrease in the uric acid excretion. Other drugs studied had no significant influence.
A continuous flow method is described for the determination of uric acid in serum using uricase and peroxidase, with omicron-dianisidine as the chromogen. The method can be used with single channel systems and with the multichannel system SMA 12/60 (Technicon). The new method was compared with six other manual and mechanized methods for the dosage of uric acid, and the results were analyzed statistically. The results from all the enzymic methods showed a good correlation, whereas the "chemical oxidation" methods showed systematic deviations.
Adenine inhibited the de novo synthesis of purines in both normal and gouty man as shown by inhibition of the incorporation of glycine-(15)N into urinary uric acid without altering the incorporation of glycine-(15)N into urinary creatinine. The diminished purine synthesis did not result in a diminution in the 24 hr excretion of uric acid. This observation was explainable in part by the prompt conversion of adenine to uric acid. In addition to this direct conversion, adenine-8-(13)C provided a slow and prolonged contribution to urinary uric acid.A feedback inhibition of purine synthesis by nucleotides derived from adenine provides the best interpretation of these results.
Oxygen-derived free radicals have been implicated in ventricular arrhythmogenesis during coronary reperfusion following an acute ischemic event. We have investigated the possibility that uric acid, a potentially important physiological antioxidant (inhibits lipid peroxidation and scavenges various radical species during oxidation to allantoin), or oxonic acid (inhibitor of uricase enzyme), are able to prevent reperfusion-induced ventricular dysrhythmias in isolated buffer-perfused rat hearts. Rat hearts (n = 12/group) underwent 15 minutes occlusion; arrhythmias were monitored during ischemia and for 10 minutes of reperfusion. There was no difference in the incidence of ventricular fibrillation or ventricular tachycardia in either uric acid or oxonic acid treated hearts compared to untreated controls. Mean duration of ventricular fibrillation appeared to be reduced in hearts treated with 10(-3) and 10(-4) M oxonic acid compared to controls but these data did not achieve a level of statistical significance. These results demonstrate that uric acid and oxonic acid failed to prevent reperfusion-mediated ventricular dysrhythmias in this experimental preparation. Although oxygen-derived free radicals may contribute to the initiation of either ischemia- or reperfusion-induced arrhythmogenesis, our findings provide little support for this hypothesis.
We have evaluated the Technicon bound uricase method for the determination of uric acid in urine with the AutoAnalyzer II. The general analytical characteristics of the method, and the effect of urine on the immobilized uricase nylon tube reactor were investigated. The method was found to be a linear up to 7.0 mmol/l with aqueous standards and up to 5.0 mmol/l with urine samples. Between-days imprecision had a coefficient of variation (CV) of 1.6% for values of about 1.2 mmol/l, and 0.8% for values above 3.5 mmol/l. Within-run imprecision gave a CV of 0.7% for values of 1.07 and 2.95 mmol/l and a CV of 0.4% for a value of 4.77 mmol/l. The mean analytic recovery was 99.1% (range 93.8-103.0%). The sample interaction was 0.9%. The correlation with the phosphotungstate method and the manual Dutch standard method was good, but the enzymatic values were 20% lower than the phosphotungstate values. Storing the immobilized uricase nylon tube reactor at 4 degrees C, when not in use, prolonged the lifetime by nearly 50%. Urine samples were not different from aqueous uric acid standards in their effect on the stability of the uricase nylon tube reactor.
Hyperuricemia associated with cisplatin therapy is considered to be a consequence of cisplatin-induced nephrotoxic reactions. We correlated changes in serum uric acid levels in patients with malignant neoplasms with tissue levels of platinum and the total dose of cisplatin. In 15 patients, the serum uric acid level increased from 6.1 +/- 1.0 mg/dL to 8.3 +/- 1.3 mg/dL during the time they were receiving cisplatin therapy. The change in uric acid level from baseline to peak correlated with both the total dose of cisplatin and the liver platinum concentration. There was no correlation with platinum concentration in the renal cortex and medulla.
Hyperuricemia-associated renal injury is closely linked to oxidative stress and inflammation, highlighting the need for safe dietary intervention. This study evaluated the protective effects of a black rice anthocyanin (ATC)-hyaluronic acid complex (HAA) against uric acid (UA)-induced injury. In UA-induced human renal proximal tubular epithelial (HK-2) cells, black rice ATCs, HA, and HAA improved cell viability and antioxidant defenses, as shown by increased glutathione (GSH) levels and catalase (CAT) and superoxide dismutase (SOD) activities. They also reduced malondialdehyde (MDA), reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β). HAA produced a greater reduction in TLR4/NF-κB-related inflammatory gene expression, suggesting that its cytoprotective and anti-inflammatory effects may be associated with modulation of this inflammatory axis. In hyperuricemic mice, HAA lowered serum UA, creatinine, and blood urea nitrogen levels, inhibited hepatic xanthine oxidase and adenosine deaminase activities, and attenuated renal histopathological injury. HAA also reduced the mRNA expression of urate reabsorption-related genes, including GLUT9, OAT4, and OAT10, while increasing that of urate excretion-related genes, including OAT1 and ABCG2, which may contribute to improved urate homeostasis. These findings support the potential of HAA as a functional dietary ingredient for the management of hyperuricemia-associated metabolic disturbances and renal injury.
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The diabetogenic activity of a range of alloxan-like compounds derived from uric acid has been investigated. The classes of derivatives were: 5-substituted-isouric acids; 4,5-disubstituted-4, 5-dihydrouric acids; 5-substituted-pseudouric acids; salts of dehydro-uramil hydrate; salts of dehydro-isouramil hydrate; alloxan derivatives. Compounds were tested by intravenous injection into rats and diabetogenic activity assessed by production of persistent hyperglycaemia and glycosuria. The only essential structural feature common to all active compounds was the presence of a quinonoid pyrimidine system or its hydrated equivalent. The presence of the five-membered ring of uric acid (or an opened form thereof) did not abolish and in some compounds enhanced diabetogenic activity.
Chickens aged five to six weeks were inoculated with three strains of Newcastle disease virus of differing pathogenicity. The serum level of the metabolites: total protein, albumin, globulin, uric acid, total lipids, cholesterol and electrolytes: calcium, magnesium, sodium and potassium were determined. The changes in serum levels of metabolites were as follows: velogenic infection was accompanied by decrease in total protein and albumin, reduction of lipids and cholesterol and increase in uric acid. No significant changes were found in the values of these metabolites in the serum of chickens infected with mesogenic strain. Lentogenic strain caused elevation of uric acid and cholesterol. All three strains caused decrease of the level of potassium in serum.
The concentration of hypoxanthine, xanthine and uric acid in the first 24-h urine of 105 newborn infants was measured densitometrically by thin-layer chromatography. 45 of them had moderate or severe perinatal complications. Among these newborns, 26 infants with perinatal complications (58%) and 4 infants without perinatal complications (7%) had an elevated urinary excretion rate of hypoxanthine. Urinary xanthine was not increased, uric acid was slightly higher in the group of infants with perinatal complication. It seems that a crucial mark is involved, if the rate of hypoxanthine exceed 15% of the total urinary oxypurine excretion, or, if related to urinary creatinine, more than 0.075 mumol hypoxanthine/mumol creatinine. Apparently, with hypoxic newborns increased values of urinary hypoxanthine excretion can be used to quantify the lack of oxygen retrospectively.
BACKGROUND: Non-alcoholic fatty liver disease is a common reason for hepatological consultation and may herald severe hepatic and extra-hepatic disease. The aetiopathogenesis of this condition is an area of increasing interest. AIM: To evaluate anthropometric and biochemical factors associated to non-alcoholic fatty liver disease in a case-control study. Methods. Demographic and biochemical data of 60 consecutive patients with bright liver absent-to-low alcohol consumption, no evidence of viral, genetic and autoimmune diseases, were compared to those of 60 age- and gender-matched historical controls without fatty liver by univariate and multiple logistic regression analysis. RESULTS: Patients were more often hypertriglyceridaemic, obese and diabetic than controls (p<.01). Mean values of alanine transaminase, gammaglutamyltranspeptidase, triglycerides, uric acid, fasting and log insulin, transferrin percent saturation and ferritin were significantly higher in the patients, while transferrin and quantitative insulin sensitivity check index, a quantitative insulin sensitivity index, were lower. No iron storage was found in those who underwent liver biopsy At univariate analysis the relative risk for non-alcoholic fatty liver disease significantly increased (p<0. 05) with increasing body mass index, fasting insulin, alanine transaminase, uric acid, triglycerides and gammaglutamyltranspeptidase; it decreased with increasing transferrin and quantitative insulin sensitivity check index. Multiple logistic regression analysis disclosed only fasting insulin and uric acid to be independent predictors of non-alcoholic fatty liver disease (p<0.05). CONCLUSIONS: Fasting insulin and serum uric acid levels indicating insulin resistance, but not indices of iron overload, are independent predictors of non-alcoholic fatty liver disease.