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PubMed1989

Effect of furosemide on transperitoneal passage of uric acid--experimental studies.

Application of furosemide (F) during peritoneal dialysis had been proposed for enlargement of peritoneal excretion of uric acid (UA), however, localization and mechanism of action of the drug remained obscure. To clarify the problem experimental studies on isolated peritoneum were performed with intention to establish whether and how transperitoneal flux of UA can be modified by F. Experiments were carried out in vitro on fragments of peritoneum taken from rabbits: parietal peritoneum and mesentery were isolated with single layer of mesothelium, and minimal amount of submesothelial tissue. Gradient of UA across the membranes was set up at 0.9-1.1 mmol/l, and flow estimated before and after addition of F (final conc. 10(-4) M) to the medium bathing either side of the membranes. Some differences in the flow between both types of the membranes as quantitative (greater flow in the parietal peritoneum), and qualitative (opposite succession of changes after F) were observed, however, the reaction for the diuretic was significant in both series of the experiments. The results confirm the suggestion that F can affect peritoneal excretion of UA during the dialysis, but at the same time they show that the mechanisms regulating the transperitoneal UA passage are complex.

Animals↗
PubMed2005

Relationships of C-reactive protein, uric acid, and glomerular filtration rate to arterial stiffness in Japanese subjects.

The relationships between C-reactive protein (CRP), uric acid (UA), glomerular filtration rate (GFR), and arterial stiffness have not been fully investigated. The aim of this study was to clarify whether CRP, UA, and estimated GFR are related to arterial stiffness estimated using brachial-ankle pulse wave velocity (baPWV). The subjects were local government employees (3412 men and 854 women). baPWV, CRP, UA, GFR, and conventional risk factors were evaluated. Multiple linear regression analyses revealed that CRP and UA were significantly related to an elevation of PWV in male and female subjects, and that the estimated GFR was significantly related to an elevation of PWV in male subjects. Significant progressive increases in baPWV were observed across the quartiles of CRP in male subjects and for UA in male and female subjects. In female subjects, the relationship of quartile CRP to baPWV had marginal significance (P = 0.055). But, in male and female subjects, quartile of estimated GFR had no significant association with PWV. These results suggest that CRP and UA are associated with an increase of arterial stiffness in male and female subjects, and that estimated GFR is possibly related to arterial stiffness in male subjects.

Adult↗
PubMed2000

The effect of mini-dose aspirin on renal function and uric acid handling in elderly patients.

OBJECTIVE: Aspirin is known to have a bimodal effect on the renal handling of uric acid (UA). High dosages (>3 gm/day) are uricosuric, while low dosages (1-2 gm/day) cause UA retention. Although very-low-dose (mini-dose) aspirin is used increasingly as a platelet aggregation inhibitor, no studies have been published on whether aspirin's renal effects occur at dosages of <0.5 gm/day. The aim of the present study was to evaluate the effects of commonly used mini-dosages of aspirin on renal function and UA handling in elderly patients. METHODS: The study included 49 elderly inpatients (age 61-94). Patients were excluded if they had renal failure, hyperuricemia, gout, or a history of bleeding, or if they were receiving anticoagulants, aspirin, or nonsteroidal antiinflammatory drugs. Previous medications and diet were kept unchanged. Aspirin was administered as follows: 75 mg/day (week 1), 150 mg/day (week 2), 325 mg/day (week 3), and 0 mg/day (week 4). Baseline and weekly samples of blood and urine were evaluated for UA, creatinine, blood urea nitrogen, creatinine clearance, UA excretion, UA clearance, and plasma levels of aspirin. RESULTS: At the lowest dosage, aspirin caused a 15% decrease in the rate of UA excretion (P = 0.045 by t-test), which was associated with a slight but significant increase in serum levels of UA (P = 0.009). These effects on UA levels were gradually reduced with increasing dosages of aspirin (multivariate analysis of variance with repeated measures showed no statistically significant difference in the rate of UA excretion between weeks 1-3 and week 0 [baseline], but the difference in serum UA levels for the same comparison was statistically significant [P = 0.038]). Generally, creatinine and UA clearance rates paralleled each other during aspirin treatment. However, 1 week after aspirin was discontinued, creatinine clearance remained decreased while UA clearance returned to baseline. Plasma aspirin concentrations were low and variable. However, patients with above-median aspirin levels had significantly greater changes in serum creatinine levels, urinary UA excretion rates, and UA clearance rates following the first week of aspirin treatment. Hypoalbuminemia and concomitant treatment with diuretics enhanced the effects of aspirin on renal function and UA retention. CONCLUSION: Mini-dose aspirin, even at a dosage of 75 mg/day, caused significant changes in renal function and UA handling within 1 week in a group of elderly inpatients, mainly in those with preexisting hypoalbuminemia. Given the widespread (and often unmonitored) use of mini-dose aspirin, especially among the elderly, these findings call for clinician alertness as well as for further studies to clarify the mechanisms underlying these phenomena.

Age Factors↗
PubMed2006

Kinetics of ozone reaction with uric acid, ascorbic acid, and glutathione at physiologically relevant conditions.

This study quantified the reaction kinetics of O3 with three low molecular weight antioxidants-uric acid (UA), ascorbic acid (AH2), and glutathione (GSH)-found in respiratory mucous. Using a semi-batch reactor in which a 500 ml/min flow of air containing 1-5 parts per million of O3 contacted 3 ml of well-stirred physiological saline solution containing 100-200 microM antioxidant, we found that: (1) mass transfer resistances in the gas and liquid phases were successfully eliminated by the reactor design; (2) the reaction of O3 with UA, AH2 and GSH had stoichiometries of 1:1, 1:1, and 1:2.5, respectively; (3) the reactivity between O3 and antioxidants was in the order UA approximately AH2>GSH. Simulating the measured amounts of O3 absorbed and antioxidant consumed with a mathematical model, reaction rate constants of O(3) with UA, AH2, and GSH were found to be 5.83 x 10(4) M(-1) s(-1), 5.5 x 10(4) M(-1) s(-1), and 57.5 M(-0.75) s(-1), respectively.

Antioxidants↗
PubMed1989

Germination of Clostridium cylindrosporum Spores on Medium Containing Uric Acid.

Clostridium cylindrosporum spores germinated rapidly under reducing conditions when bicarbonate, uric acid, and calcium were present. Germination rates on 10 mM urate increased with increasing Ca (maximum rate at 5 mM Ca or greater). Germination rates on urate (limiting Ca) increased with increasing urate concentrations to 10 mM urate. At 10 mM Ca, germination rates reached a maximum at 1 mM urate and remained constant thereafter. Cations (Na, K, Li, and Mg), purines, purine analogs, and EDTA inhibited germination at limiting calcium concentrations but not (except for 10 mM adenine) at 10 mM Ca. Methyl viologen or formate did not inhibit germination. Germination was not observed in solutions containing xanthine, hypoxanthine, caffeine, theophylline, 6,8-dihydroxypurine, adenine, allopurinol, formate, glycine, or acetate, even though some of the purines are growth substrates.

Journal Article↗
PubMed1992

Population based data on urinary excretion of calcium, magnesium, oxalate, phosphate and uric acid in children from Cimitile (southern Italy).

Population based data on 24-h urinary excretion of calcium, oxalate, magnesium, phosphate, uric acid and creatinine were collected from 220 children (aged 3-16 years) living in Cimitile, Campania, southern Italy. Mean excretion rates for 7 days were correlated with age, body weight, body mass index and height. The prevalence of hypercalciuria (greater than 4 mg/kg body weight) and of hyperoxaluria (greater than 60 mg/day) were 9.1% and 1.8%, respectively. The same 20 children were also identified as hypercalciuric when a calcium/creatinine ratio of greater than 0.15 was considered. No significant differences between boys and girls were found in the urinary excretion of the five constituents implicated in urolithiasis. The study data provide additional childhood reference values for urinary excretion of compounds related to stone formation.

Adolescent↗
PubMed2003

Fructose and its effect on turkey plasma uric acid levels and productive performance.

Previous studies have shown that addition of fructose to the diet of broilers raises plasma uric acid (PUA) concentration and improves productive performance. The purpose of this experiment was to establish the effect of feeding fructose on turkey PUA concentration and productive performance. Turkey poults (n = 64) were weighed and randomly assigned to diets containing 0 (control), 5, 10, and 15% fructose with four replicates of four poults each per treatment. All diets were isocaloric and isonitrogenous. Feed and water were offered ad libitum for 14 wk. Body weights were measured biweekly throughout the study, and blood samples were drawn from wk 8 to 10 for determination of PUA concentration, leukocyte oxidative activity (LOA), and differential leukocyte counts. Relative liver size (g/kg BW) was also determined. The heaviest body weights were recorded from turkeys fed 10% fructose diet (P < 0.05). Supplemental fructose had no effect on the feed to gain ratio, relative liver size, or PUA concentrations. LOA increased in poults fed the 15% fructose diet. Turkeys fed 10 and 15% fructose diets had higher monocyte and lower polymorphonuclear lymphocyte counts (P < 0.05) compared to those fed control and 5% fructose diets. Feeding fructose to turkeys at 10% of the diet improved productive performance. However, dietary fructose had no effect on PUA or, consequently, LOA.

Animal Nutritional Physiological Phenomena↗
PubMed1995

Effect of insulin on uric acid excretion in humans.

Although hyperuricemia is a frequent finding in insulin-resistant states, insulin's effect on renal uric acid (UA) handling is not known. In 20 healthy volunteers, diastolic blood pressure, body weight, and fasting plasma insulin were positively (and age was negatively) related to fasting plasma UA concentrations, together accounting for 53% of their variability. During an insulin clamp, urine flow was lower than during fasting conditions (1.01 +/- 0.12 vs. 1.56 +/- 0.32 ml/min, P = 0.04), whereas creatinine clearance was unchanged (129 +/- 7 and 131 +/- 9 ml/min, P = not significant). Hyperinsulinemia did not alter serum UA concentrations (303 +/- 13 vs. 304 +/- 12 microM) but caused a significant decrease in urinary UA excretion [whether expressed as absolute excretion rate (1.66 +/- 0.21 vs. 2.12 +/- 0.23 mumol/min, P = 0.03), clearance rate (5.6 +/- 0.8 vs. 7.3 +/- 0.8 ml/min, P = 0.03), or fractional excretion (4.48 +/- 0.80 ml/min vs. 6.06 +/- 0.64%, P < 0.03)]. Hyperinsulinemia was also associated with a 30% (P < 0.001) fall in urine Na excretion. Fractional UA excretion was related to Na fractional excretion under basal conditions (r = 0.59, P < 0.01) and during the insulin period (r = 0.53, P < 0.02). Furthermore, the insulin-induced changes in fractional UA and Na excretion correlated with one another (r = 0.66, P < 0.001). Physiological hyperinsulinemia acutely reduces urinary UA and Na excretion in a coupled fashion.

Adult↗
PubMed1975

Localization of renal tubular uric acid transport defect in gouty chickens.

Chickens genetically selected for high incidence of articular gout and hyperuricemia were used to determine the site of defective uric acid (UA) transport in gout. The Sperber technique was used to compare the tubular secretion of preformed UA with the tubular secretion of UA formed within the tubular cells in gouty and nongouty chickens of the same strain. In gouty chickens, the tubular excretion ratio of preformed [14C]UA was 36% of the value obtained in nongouty chickens of the same strain, whereas the tubular excretion ratios of [14C]UA formed within the tubular cells from [14C]guanine were equal in the two types of chickens. This suggests that a UA transport is located at the peritubular membrane and that this mechanism is defective in gouty chickens. In addition, the transport of p-aminohippurate (PAH) was normal in gouty chickens, which suggests that the transport mechanism for UA is distinct from that for PAH.

Aminohippuric Acids↗
PubMed1984

Problems associated with the measurement of uric acid using two enzyme-mediated reaction systems.

We describe the problems encountered with the adaptation of two enzymatic assays for uric acid to a centrifugal analyser. A method employing the uricase/catalase/aldehyde dehydrogenase enzyme system sometimes suffered from interference due to light-scattering species in samples and reagents. The second method employing the uricase/peroxidase system gave results that were lower than the comparison method.

Acetates↗
PubMed1979

[Automatic determination of triglyceride, cholesterol, glucose and serum uric acid in the screening for preventive medicine (author's transl)].

A centrifuge speed analyzer, used for triglyceride, cholesterol, glucose and serum uric acid determinations, was tested as to linearity, precision, steadiness and accuracy requirements. The results were compared to those obtained by other techniques. Automatic techniques were proved to comply with reliability and practicability requirements, necessary during the screenings for preventive medicine. The centrifuge speed analyzer seems to be particularly fit for the primary prevention trials of coronary heart disease, since the follow-up studies require repeated laboratory examinations.

Adult↗
PubMed2004

Altered circadian relationship between serum nitric oxide, carbon dioxide, and uric acid in multiple sclerosis.

The free radical nitric oxide (NO*) is involved in a variety of diverse biological processes from acting as a vasodilator in the cardiovascular system to being the rate-limiting component in the production of peroxynitrite (ONOO-), a contributor to neurodegenerative disorders such as multiple sclerosis (MS). Uric acid (UA), the end product of purine metabolism in humans and a selective inhibitor of toxic reactions attributed to radicals formed by the interaction of ONOO- and CO2, is generally low in MS patients. We investigated the relationship between serum ONOO-, CO2, and UA in MS patients and normal controls by comparing the circadian characteristics of the NO* metabolites nitrite/ nitrate (NO), CO2, and UA. In this preliminary study, we found the functional relationship ascribed to the circadian timing of the peak and trough levels of NO, CO2, and UA in healthy subjects to be clearly altered in MS patients. These findings suggest that alterations in the temporal relationship between the 24h pattern in serum ONOO- formation and UA may either contribute to or reflect the disease processes in MS.

Adult↗
PubMed2005

Uric acid may inhibit glucose-induced insulin secretion via binding to an essential arginine residue in rat pancreatic beta-cells.

Uric acid (1a) suppresses basal insulin release in isolated rat pancreatic islets and inhibition of glucose-stimulated insulin secretion (GSIS) occurs right at hyperuricaemic levels (0.4 mM). Conversely, 1 mM guanidinium urate (2a) was completely ineffective, strongly suggesting that binding to an essential arginine residue triggers the inhibitory effect. A specific recognition of 1a molecule at the crucial beta-cell receptor is probably involved in the blocking glucose signal transduction.

Animals↗
PubMed1987

In vivo electrochemical detection of 5-hydroxyindoles in the dorsal horn of the spinal cord: the contribution of uric acid to the voltammograms.

Treated carbon fiber electrodes were used with differential normal pulse voltammetry (DNPV) for in vivo determination of the relative participation of uric acid (UA) to peak 3 derived between 250-300 mV in the dorsal horn of the spinal cord of anesthetized rats. In vitro, treated carbon fiber electrodes respond linearly over a large range of concentrations of UA (oxidation potential around 250 mV) and 5-hydroxyindoleacetic acid (5-HIAA, oxidation potential around 280-290 mV), but are 3 to 4 times more sensitive to 5-HIAA than to UA. In vivo the question remains as to the exact nature of peak 3 because the difference between oxidation potentials of UA and 5-HIAA is not great enough to permit a separate monitoring of the two compounds. In normal rats, administration of the xanthine oxidase inhibitor allopurinol, produced a progressive decrease of the signal, which reached 64.3% of controls at 120 min (35.6% diminution) after injection, and then plateaued around this value for up to 2 h. The administration of the monoamine oxidase inhibitor (MAOI) clorgyline, produced a classical decay in the voltammograms due to a diminution of endogenous 5-HIAA; however, allopurinol injected 3 h after MAOI gave an additional decrease of peak 3 of about 28%. Finally, in rats pretreated with parachlorophenylalanine (pCPA), the residual peak (32.48% as compared to peak 3 of normal rats taken as 100%), the potential of which is shifted to near that of UA, could be decreased by allopurinol to a level of 9.6% of the peak in control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Allopurinol↗
PubMed1986

[Dissolution of obstructive uric acid calculi by percutaneous nephrostomy and in situ alkalinization].

Following the introduction of one or two percutaneous nephrostomy drains, 16 obstructive uric acid calculi were treated by perfusion of excretory cavities with 14% sodium bicarbonate solution. Twelve calculi had dissolved within an average of 5 days, 1 required percutaneous lithotripsy because of incomplete dissolution and 3 were unaltered. Success of this treatment appears to be dependent on the total radiotransparency of calculi, a feature difficult to demonstrate. There were no reports of major complications. The only weakly invasive nature of alkalinization in situ makes it a method of choice to be reserved for obstructive calculi, and a therapeutic strategy is proposed.

Aged↗