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At least 1,117 records · Page 62Linked to original sources
PubMed1996

[Level of uric acid in aqueous humor of patients with cataract].

Aqueous humor was taken from 32 patients with senile and presenile cataract at the operation by means of anterior chamber puncture. Uric acid was marked by indirect method with uricase. The mean content of uric acid in aqueous humor of patients with cataract was 187.13 mumol/l and in the control group 309.34 mumol/l. The difference between the groups is statistically significant. The results suggest that uric acid as strong endogenous antioxidant may play an important role in pathogenesis of cataract.

Adult↗
PubMed1977

Uptake of uric acid by separated renal tubules of the rabbit. II. Effects of drugs.

The effect of various drugs on the rate of uptake of uric acid by separated renal tubules of the rabbit was investigated. Determinations were made of 150 values and slopes of the inhibition curves. The most potent inhibitor of uric acid uptake was sulfinpyrazone, with an 150 of 0.02 mM. Calcium ipodate and benzbromarone were also potent inhibitors. Uricosuric drugs, with the exception of benzbromarone, had shallow inhibition slopes. Diuretic drugs had steep inhibition slopes. More than one mechanism of action is probably involved in the inhibition of uric acid uptake in separated renal tubules by drugs.

Animals↗
PubMed1993

A study of uric acid metabolism and gouty arthritis in patients with polycystic kidney.

It has been found that polycystic kidney (ADPKD) is often associated with gout. On the other hand, there are reports describing that the hyperuricemia (HU) seen in ADPKD corresponds to a reduction in renal function. We investigated the uric acid metabolism in 44 patients with ADPKD (age, 50 +/- 12.8 years; CCR, 50.5 +/- 41.1 ml/min) at our hospital. From among these 44 patients, 14 with a CCR of 80 ml/min were selected. Their data for uric acid metabolism were compared against those from the previous year's studies on various disease types (114 normal subjects, 70 with membranous nephropathy, 175 with IgA nephritis, 122 with gout, 137 with asymptomatic hyperuricemia, and 42 with diabetes mellitus). Among the 44 patients with ADPKD, the serum uric acid (SUA) was 7.7 +/- 1.9 mg/dl and HU affected 28 (63.6%). The incidence of gouty arthritis was also high (6 patients, 13.6%), revealing a positive correlation between SUA and CCR. Compared with membranous nephropathy and IgA nephritis, ADPKD exhibited an accentuated increase in SUA associated with a reduction in CCR. It is believed that this represents a factor for a high incidence of complications of hyperuricemia and gouty arthritis in ADPKD in contrast to other diseases. However, no increase in the production of uric acid was noted in ADPKD.

Adult↗
PubMed2005

Cetyltrimethylammonium bromide-enhanced chemiluminescence determination of uric acid using a luminol-hexacyanoferrate(III)-hexacyanoferrate(II) system.

A chemiluminescence (CL) method using flow injection (FI) was developed for the determination of uric acid based on the enhancement chemiluminescence intensity of luminol-hexacyanoferrate(III)-hexacyanoferrate(II) in the presence of cetyltrimethylammonium bromide and the uric acid species. The linear range was 7.0 x 10(-10) - 9.0 x 10(-7) M with a detection limit (3sigma) of 2.58 x 10(-10) M, which was about two orders of magnitude lower than those reported. The proposed method was used for the determination of uric acid in real samples.

Cetrimonium↗
PubMed1996

[Level of uric acid in aqueous and vitreous humor of man].

Uric acid-a potent endogenous antioxidant-may play a certain role in some eye diseases. However, its content in intraocular humors has not been examined so far. Samples of aqueous and vitreous humor were collected from 32 dead persons for examination. Uric acid was marked by indirect method with uricase. Uric acid level in aqueous humor ranges from 166.67 to 446.4 mumol/l (mean 309.34), whereas in vitreous humor from 77.38 to 452.00 mumol/l (mean 220.80).

Aqueous Humor↗
PubMed1991

Anomalously high concentrations of brain extracellular uric acid detected with chronically implanted probes: implications for in vivo sampling techniques.

The height of peak 2, h2, recorded using linear sweep voltammetry with 350-micron-diameter carbon paste electrodes in rat striatum was measured from the day of implantation (day 0) to 4 months after surgery. The value of h2 was at a minimum on day 0 (0.6 +/- 0.2 nA; n = 20), rose sharply to a maximum on day 2 (6.3 +/- 0.9 nA; n = 12), and decreased to a stable level by day 7 (3.3 +/- 0.7 nA; n = 16), which lasted for 4 months (3.2 +/- 0.6 nA; n = 9). These changes were shown by microinfusion of uricase to be due to variations in the concentrations of extracellular uric acid, although h2 appears to have a small baseline contribution of approximately 0.3 nA from 5-hydroxyindoleacetic acid. The stable value of h2 recorded under chronic conditions was estimated to correspond to a minimal uric acid concentration of 50 mumol/L, which represents a 10-fold increase in the extracellular level of this purine metabolite compared with the initial (acute) value. Very similar results were obtained using a microdialysis technique that detected uric acid directly. These estimates of striatal uric acid concentration are in marked contrast to those obtained using 40-micron diameter carbon fiber electrodes, which showed a decrease from the acute preparation to less than 1 mumol/L under chronic conditions. Large values of h2 were also recorded with chronically implanted paste electrodes in the hippocampus and frontal cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

Serum cholesterol, uric acid and cholinesterase in victims of the Tokyo subway sarin poisoning: a relation with post-traumatic stress disorder.

Cholesterol and uric acid, which might correlate with steroidogenesis and monoamine functions, may change under emotionally stressful conditions and in mental disturbances. Among anxiety disorders, an increase of serum cholesterol has been observed in panic disorder. However, the issue has not been adequately investigated in other anxiety disorders, including post-traumatic stress disorder (PTSD). The present study investigated serum cholesterols, uric acid and cholinesterase in victims of the Tokyo subway sarin poisoning, 1995, in a series of 5-year follow-ups. Cholinesterase was studied, in relevance with serum lipid changes and symptoms of PTSD, and also in light of a biological effect of sarin. Out of 34 victims, eight developed PTSD and two were currently diagnosed with PTSD using the Clinician-Administered PTSD Scale (CAPS). No significant relationship was observed between PTSD and serum cholesterols or uric acid. Several factors including co-occurrence of other mental disturbances with PTSD, in addition to the limited sample size, might have affected the result. In contrast, serum cholinesterase level was significantly reduced in the victims with the development of PTSD, compared with the matched controls (P<0.02, t-test). This might partly reflect a long-term remnant effect of sarin intoxication, although an effect of the psychological experience could not be totally excluded.

Adult↗
PubMed1989

Inactivation of alpha 1-antiproteinase by hydroxyl radicals. The effect of uric acid.

The elastase-inhibitory activity of alpha 1-antiproteinase is inactivated by hydroxyl radicals (.OH) generated by pulse radiolysis or by reaction of iron ions with H2O2 in the presence of superoxide or ascorbate. Uric acid did not protect alpha 1-antiproteinase against inactivation by .OH in pulse radiolysis experiments or in the superoxide/iron/H2O2 system, whereas it did in systems containing ascorbic acid. We propose that radicals formed by attack of .OH on uric acid are themselves able to inactivate alpha 1-antiproteinase, but that these uric acid radicals can be 'repaired' by ascorbic acid.

Ascorbic Acid↗
PubMedDate not supplied

Renal handling of uric acid in man.

The uricosuric response to 80 mg of micronized Benzbromarone was employed to assess the renal tubular secretory site for uric acid in patients with primary gout. Since Benzbromarone selectively inhibits tubular reabsorption of secreted urate, the maximum uricosuria induced by this drug can be equated with the minimal secretory rate. Furthermore, a significant relationship was noted in normal controls between urate secretion and the plasma urate concentration (r = 0.956, p less than 0.005). Using the Benzbromarone response as a measure of tubular secretion, gouty patients with normal production hyperuricemia had a significantly lower secretory rate by comparison to patients with overproduction of uric acid. These data indicate that in patients with primary normal production hyperuricemia, the renal tubular defect is related to a decreased secretory response for a given plasma concentration of uric acid.

Adult↗
PubMed1983

[Modification of serum uric acid concentration under long-term therapy with the lipid-regulating drug Duolip].

During an 8-months treatment period the effect of Duolip on serum uric acid in 112 patients with hyperlipidemia was studied. In this open clinical trial a long-lasting hypouricemic effect could be shown for Duolip. This response was more pronounced with higher initial serum uric acid concentrations and could only be observed in patients with serum uric acid levels above 6.4 mg%. Thus, in one patient both risk factors of atherosclerosis--hyperlipidemia and hyperuricemia--can be treated by a single drug.

Clofibrate↗
PubMed1986

Depression of glutamine-stimulated uric acid production and blood glutamine accumulation by insulin in chickens.

This experiment was conducted to examine effects of insulin on glutamine accumulation in blood and uric acid production in the chicken infused with glutamine. Insulin pretreatment eliminated the stimulatory effect of glutamine infusion on urinary uric acid excretion in the chicken fed a 5% protein diet, which resulted in no increase in urinary total nitrogen excretion by the infusion. In the chicken fed a 20% protein diet the pretreatment with insulin did not have such clear depressive effects on the increases in urinary uric acid and total nitrogen excretion caused by the glutamine infusion. Insulin tended to depress the increases in plasma glutamine concentration caused by the infusion of glutamine at both levels of dietary protein intake.

Animals↗
PubMed1996

[Uric acid level in aqueous humor of patients with cataract].

Aqueous humor was taken from 32 patients with senile and presenile cataract at the operation by means of anterior chamber puncture. Uric acid was marked by indirect method with uricase. The mean content of uric acid in aqueous humor of patients with cataract was 187.13 mumol/l and in the control group 309.34 mumol/l. The difference between the groups is statistically significant. The results suggest that uric acid as strong endogenous antioxidant may play an important role in pathogenesis of cataract.

Adult↗
PubMed1986

Serum creatinine and uric acid levels in pregnant urban African and Caucasian women.

Serum creatinine and uric acid concentrations were determined for 117 pregnant urban African women and 109 pregnant Caucasian women covering the three trimesters of pregnancy. The creatinine levels for Caucasians rose as pregnancy progressed, exceeding the normal adult level, while that for Africans rose only slightly and only during the last trimester of pregnancy. A similar observation was made for uric acid levels except that the rise in Africans commenced earlier than it did for creatinine, commencing from about the second trimester. Also, the levels in both groups of people remained within the normal adult range. The increased levels of these non-protein nitrogen compounds during pregnancy was attributable to increased metabolism associated with the condition. The difference observed between the Caucasians and Africans was attributed to the better protein nutritional status of the former. It is suggested that the creatinine "curve" especially for the Caucasians could be utilized in the monitoring of foetal well-being.

Adult↗
PubMed1992

Racial variation in serum uric acid concentration in pregnancy: a comparison between European, New Zealand Maori and Polynesian women.

A prospective study was undertaken to measure serum uric acid levels in normal pregnant women of different races, to ascertain if there was any significant interracial variation. A total of 48 women were studied of which 13 were European, 11 New Zealand Maori, 22 Pacific Islanders and 2 Indian. In the second trimester, European, Maori and Cook Island women had similar uric acid levels and other Polynesian groups showed significantly higher levels. In the third trimester, both Maori and Cook Island women showed a marked rise so that their levels came to equal those of other Polynesian groups, all 3 having significantly higher levels than European women. The importance of these observations relates to the use of uric acid levels in the management of patients with gestational proteinuric hypertension. It is possible that in these cases unusually high results may alarm the clinician into hasty intervention.

Adolescent↗
PubMed1995

A method for the simultaneous determination of creatinine and uric acid in serum by high-performance-liquid-chromatography evaluated versus reference methods.

A high performance liquid chromatography (HPLC) with isocratic ion-pair-reversed-phase separation and simultaneous UV-detection at 232 nm and 292 nm is proposed as a method for the simultaneous determination of uric acid and creatinine in serum. The only sample preparation required is an appropriate dilution with the eluent and membrane filtration on non-adsorbent 0.2 micron membrane-filtration-devices. The inaccuracy of the method has been determined for NIST-SRM-909 (n = 10) and was + 0.5% for creatinine as well as for uric acid. The imprecision in this case was 0.8% for both analytes. The within-run imprecision for creatinine/uric acid was 0.4-0.5%/0.2-0.4% in the case of standards and 0.6-0.8%/0.4-0.7% in the case of serum-pools. The between-run imprecision for creatinine/uric acid obtained from serum pools was 0.8-1.1%/0.7-1.0%. The results for creatinine have been compared to those from an isotope dilution-gas chromatography-mass spectrometry using [13C, 15N2]creatinine as internal standard and selected mass detection at m/e = 329 and m/e = 332. The results for uric acid have been compared to an HPLC-method published previously (Kock R et al. J Clin Chem Clin Biochem 1989; 27:157-62). The method comparisons (n = 55) for the new combined method presented versus the reference method for creatinine and the candidate reference method for uric acid resulted in coefficients of correlation of r = 1.000 for both analytes. The new combined method presented is useful for the analysis of patient samples where the classical photometric procedures do not give reliable results, as often observed in monitoring after transplantation surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, High Pressure Liquid↗
PubMed2002

Studies on the pathophysiology of the low urine pH in patients with uric acid stones.

BACKGROUND: A very low urine pH is the major risk factor for uric acid stone formation. METHODS: A subgroup of patients with a history of uric acid stones and a persistently low urine pH (<5.5 for at least 12 h/day) were selected for detailed study. Based on their relative ammonium (NH(+)(4)) and sulfate (SO(2-)(4)) excretions, patients were divided into two groups. RESULTS: The first group (N = 2) excreted 173 and 139% more NH(+)(4) than SO(2-)(4). Their daily urinary unmeasured anion excretion was higher than their calculated net diet alkali input (38 and 61 vs. 24 and 49 mEq, respectively). In the second group (N = 12), NH(+)(4) excretion was 69 +/- 5% that of SO(2-)(4). In 2 of 12, decreased renal ammoniagenesis was suspected due to a plasma potassium of 5.3 mmol/L and/or a lower GFR (65 and 59 L/day); these patients had an extremely low citrate excretion (3 and 1 mEq/day). In contrast, citrate excretion was not low in the remaining 10 patients (10.4 +/- 1.3 mEq/day). CONCLUSIONS: Patients in group 1 needed a higher NH(+)(4) excretion possibly because of a H+ load from excessive renal excretion of organic anions. We speculate that an alkaline proximal tubular cell pH could be the basis for the low NH(+)(4) and high citrate excretions in 10 of 12 patients in group 2. Dietary factors and/or a molecular lesion may contribute to their pathophysiology.

Adult↗
PubMed2004

Uric acid and allantoin levels in Down syndrome: antioxidant and oxidative stress mechanisms?

BACKGROUND: Down syndrome (DS) is a chromosomal abnormality (trisomy 21) leading to mental retardation, to the characteristic change of individual's phenotype and to the pathological features of Alzheimer disease. Patients with DS have elevated ratio of superoxide dismutase to (catalase plus glutathione peroxidase) with respect to controls in all age categories suggesting that oxidative imbalance contributes to the clinical manifestation of accelerated aging. RESULTS: We report that persons with DS have elevated uric acid levels compared with controls, 348.56+/-22.78 versus 284.00+/-20.86 micromol/l (p=0.018). The levels of hypoxanthine and xanthine in DS children (6.35+/-0.31 and 1.02+/-0.23 micromol/l) were significantly lower than in controls (7.83+/-0.59 and 2.43+/-0.66 micromol/l). This result suggests increased conversion of hypoxanthine and xanthine to uric acid with subsequent free radical-dependent oxidation of uric acid to allantoin, mechanisms potentiated by the oxidative stress in DS. Allantoin is a nonenzymatic oxidative product of uric acid in human. In DS individuals, the levels of allantoin were significantly higher than those in healthy controls (18.58+/-2.27 and 14.07+/-1.07 micromol/l, respectively, p=0.03). CONCLUSIONS: Our data supported the presumption of increased oxidative stress in DS.

Adolescent↗
PubMed1987

Deproteinizing methods evaluated for determination of uric acid in serum by reversed-phase liquid chromatography with ultraviolet detection.

We evaluated six deproteinizing methods for determination of uric acid in serum by "high-performance" liquid chromatography with ultraviolet detection: those involving zinc hydroxide, sodium tungstate, trichloroacetic acid, perchloric acid, acetonitrile, and centrifugal ultrafiltration (with Amicon MPS-1 devices). We used a Toyosoda ODS-120A reversed-phase column. The mobile phase was sodium phosphate buffer (40 mmol/L, pH 2.2) containing 20 mL of methanol per liter. Absorbance of the eluate was monitored at 284 nm. The precipitation method with perchloric acid gave high recoveries of uric acid and good precision, and results agreed with those by the uricase-catalase method of Kageyama (Clin Chim Acta 1971;31:421-6).

Chemical Precipitation↗