Separation of urea, uric acid, creatine, and creatinine by micellar electrokinetic capillary chromatography with sodium cholate.
(1/2112)
The capillary electrophoretic separation of the four nonprotein nitrogenous compounds (NPNs; urea, uric acid, creatine, and creatinine) typically employed in clinical and medical settings for the monitoring of renal function is described. Successful resolution of these compounds is achieved with the use of a bile salt micelle system composed of sodium cholate at phosphate buffer pH 7.4. The elution patterns of four NPNs are obtained within 30 min with a voltage of 30 kV. The effect of varying the applied voltage, temperature, and the mole ratio of phosphate buffer with bile salt surfactant on the migration behavior is also examined. (+info)
Five caffeine metabolite ratios to measure tobacco-induced CYP1A2 activity and their relationships with urinary mutagenicity and urine flow.
(2/2112)
To choose a sensitive protocol to discriminate populations exposed and not exposed to inducers, five urinary metabolite ratios (MRs) [MR1 (17X + 17U)/137X, MR2 (5-acetylamino-6-formylamino-3-methyluracil [AFMU] + 1X + 1U)/17U, MR3 (17X/137X), MR4 (AFMU + 1X + 1U + 17X + 17U)/137X, and MR5 (AFMU + 1X + 1U)/17X] were calculated in 4-5 h and 0-24 h urine samples after caffeine intake. One hundred twenty-five healthy volunteers (59 nonsmokers and 66 smokers) were included in the study. All ratios showed a log-normal distribution. MR2 in the two time intervals was the only ratio nondependent on the urine flow. Differences between nonsmokers and smokers could be detected with all ratios at 4-5 h. However, only MR2 and, to a lesser extent, MR5 allowed the discrimination of higher cytochrome P450 1A2 (CYP1A2) activity in smokers in the 0-24 h sample. Although smokers had increased urinary mutagenicity in relation to nonsmokers, a significant association between MRs and urine mutagenicity was observed only with MR2 in the 4-5 h interval; this ratio/time schedule being that of higher association with tobacco consumption. The most flow-dependent ratios, MR1, MR3, and MR4, were closely correlated with each other at the two intervals. The flow dependency profile of each ratio may explain their different power to indicate both tobacco exposure and tobacco-derived mutagenicity. In conclusion, MR2 in the period of 4-5 h after caffeine intake seems preferable, especially at high urine flow rates. (+info)
Gout and hyperuricemia.
(3/2112)
Gout is a condition characterized by the deposition of monosodium urate crystals in the joints or soft tissue. The four phases of gout include asymptomatic hyperuricemia, acute gouty arthritis, intercritical gout and chronic tophaceous gout. The peak incidence occurs in patients 30 to 50 years old, and the condition is much more common in men than in women. Patients with asymptomatic hyperuricemia do not require treatment, but efforts should be made to lower their urate levels by encouraging them to make changes in diet or lifestyle. Acute gout most commonly affects the first metatarsal joint of the foot, but other joints are also commonly involved. Definitive diagnosis requires joint aspiration with demonstration of birefringent crystals in the synovial fluid under a polarized light microscope. Treatment includes nonsteroidal anti-inflammatory drugs (NSAIDs), colchicine, corticosteroids and analgesics. In patients without complications, NSAID therapy is preferred. (+info)
Sparing effect of hemiplegia on tophaceous gout.
(4/2112)
The sparing effect of hemiplegia on the development of tophaceous gout is described. The useless upper limb had no tophaceous deposits and the partially paralysed lower limb had only limited urate deposits. Disuse was presumably the major contributor to the limited deposition of urates on the paralysed side. (+info)
Soccer players under regular training show oxidative stress but an improved plasma antioxidant status.
(5/2112)
Physical activity is known to induce oxidative stress in individuals subjected to intense exercise. In this study, we investigated the lipoprotein profile and the plasma antioxidant status in a group of soccer players engaged in a regular training programme. As was expected for aerobic exercise, high-density lipoprotein-cholesterol (HDL-C) and HDL3-C levels were significantly increased in the sportsmen (P<0.05). Total plasma antioxidant capacity was 25% higher in sportsmen than in controls (P<0.005). Accordingly, plasma hydrosoluble antioxidant levels (ascorbic acid and uric acid) were found to be significantly elevated in the soccer players (P<0.005). In addition, these subjects showed high concentrations of alpha-tocopherol in plasma compared with controls (P<0.005). Furthermore, an increase in plasma superoxide dismutase activity was also observed in relation to exercise (P<0.01). The elevation in plasma activities of antioxidant enzymes and the higher levels of free radical scavengers of low molecular mass may compensate the oxidative stress caused by physical activity. High levels of high-density lipoprotein in plasma may offer additional protection by inhibiting low-density lipoprotein oxidation and thus liposoluble antioxidant consumption. Therefore, soccer players under regular training show an improved plasma antioxidant status in comparison to sedentary controls. (+info)
Urate synthesis in the blood-sucking insect rhodnius prolixus. Stimulation by hemin is mediated by protein kinase C.
(6/2112)
Hemin is a catalyst of the formation of reactive oxygen species. We proposed that hematophagous insects are exposed to intense oxidative stress because of hemoglobin hydrolysis in their midgut (Petretsky, M. D., Ribeiro, J. M. C., Atella, G. C., Masuda, H., and Oliveira, P. L. (1995) J. Biol. Chem. 270, 10893-10896). We have shown that hemin stimulates urate synthesis in the blood-sucking insect Rhodnius prolixus (Graca-Souza, A. V., Petretsky, J. H., Demasi, M., Bechara, E. J. H., and Oliveira, P. L. (1997) Free Radical Biol. Med. 22, 209-214). Once released by fat body cells, urate accumulates in the hemolymph, where this radical scavenger constitutes an important defense against blood-feeding derived oxidative stress. Incubation of Rhodnius fat bodies with okadaic acid raises the level of urate synthesis, suggesting that urate production can be controlled by protein phosphorylation/dephosphorylation. Urate synthesis is stimulated by dibutyryl cAMP and inhibited by N(2((p-bromocinnamil)amino)ethyl)-5-isoquinolinesulfonamide (H-89), an inhibitor of protein kinase A, as well as activated by the protein kinase C activator phorbol 12-myristate 13-acetate. In the presence of hemin, however, inhibition of urate synthesis by H-89 does not occur, suggesting that the hemin stimulatory effect is not mediated by protein kinase A. Calphostin C completely inhibits the hemin-induced urate production, suggesting that the triggering of urate antioxidant response depends on protein kinase C activation. This conclusion is reinforced by the observation that in fat bodies exposed to hemin, both protein kinase C activity and phosphorylation of specific endogenous polypeptides are significantly increased. (+info)
Ascorbate prevents prooxidant effects of urate in oxidation of human low density lipoprotein.
(7/2112)
Uric acid and ascorbic acid are important low molecular weight antioxidants in plasma. Their interactions and combined effect on Cu(2+)-catalysed oxidation of human low density lipoprotein were studied in vitro. It was found that uric acid alone becomes strongly prooxidant whenever it is added to low density lipoprotein shortly after the start of oxidation (conditional prooxidant). Ascorbic acid, which is present in human plasma at much lower concentrations (20-60 microM) than urate (300-400 microM), is in itself not a conditional prooxidant. Moreover, ascorbate prevents prooxidant effects of urate, when added to oxidising low density lipoprotein simultaneously with urate, even at a 60-fold molar excess of urate over ascorbate. Ascorbate appears to have the same anti-prooxidant effect with other aqueous reductants, which, besides their antioxidant properties, were reported to be conditionally prooxidant. Such interactions between ascorbate and urate may be important in preventing oxidative modification of lipoproteins in the circulation and in other biological fluids. (+info)
Favorable life-style modification and attenuation of cardiovascular risk factors.
(8/2112)
In order to develop an effective counseling system for prevention of cardiovascular diseases, the association of a favorably changed life-style with improved risk factors was examined. Participants were 7,321 office workers aged 30-69 years from in and around Nagoya city. The age-adjusted odds ratio (OR) and its 95% confidence interval (CI) were calculated to assess the likelihood of risk factor improvement by favorable life-style modifications during a 3-year period. Those who began to eat breakfast and increased their vegetable intake normalized their previously abnormal diastolic blood pressure with more than twice the likelihood (adjusted OR [95% CI] 2.89 [1.29-6.46] and 2.60 [1.18-5.75], respectively). 'Began to eat breakfast' was also significantly associated with normalized total cholesterol (TC) (1.84, [1.05-3.21]). 'Stopped eating till full' significantly normalized the body mass index (2.03; [1.25-3.28]), uric acid (1.65; [1.07-2.52]) and TC (1.43; [1.04-1.97]). Those who started regular exercise significantly normalized their high-density lipoprotein-cholesterol (HDL-C) abnormality with 1.69-times the likelihood (1.69; [1.24-2.29]) and those who began to walk briskly also improved their TC abnormality (1.85; [1.19-2.89]). HDL-C was normalized with 2.55-times the likelihood in those who quit smoking (2.55; [1.68-3.86]). Because favorable life-style modifications can attenuate abnormal cardiovascular risk factors, then proper advice on specific risk factors should be routinely given at each health check-up in order to prevent the onset of cardiovascular diseases in subsequent years. (+info)