Effects of bovine milk ingestion on urinary excretion of oxypurinol and uric acid.

OBJECTIVE: Although allopurinol is a xanthine oxidase inhibitor, its overall effect may be due to the action of oxypurinol, a metabolite of allopurinol and another xanthine oxidase inhibitor, since the biological half-life of oxypurinol is longer than that of allopurinol. Oxypurinol shares a renal transport pathway with uric acid and ingestion of bovine milk increases the urinary excretion of uric acid. Therefore, we investigated whether its ingestion promotes the urinary excretion of oxypurinol. SUBJECTS/METHODS: Bovine milk (15 ml/kg body weight) was administered to 6 healthy subjects who took allopurinol (300 mg) 12 h prior to ingestion. In addition, a control experiment was performed with the same subjects using the same protocol, except for the ingestion of water instead of bovine milk. Blood and urine samples were collected before and after bovine and water ingestion. RESULTS: In the bovine milk ingestion experiment, the urinary excretion values of oxypurinol and uric acid were increased by 18% and 38%, respectively, and the fractional excretion values of oxypurinol and uric acid were increased by 20% and 40%, respectively, whereas those did not change in the control experiment. In addition, the concentration of alanine and sum of concentrations of amino acids were increased by 16% and 20%, respectively, in the bovine milk ingestion experiment. CONCLUSION: These results suggest that bovine milk ingestion promotes the urinary excretion of oxypurinol as well as uric acid by increasing amino acid concentration.

Serum CRP in patients with gout and effects of benzbromarone.

OBJECTIVE: C-reactive protein (CRP) is associated with increased risk for myocardial infarction, atherosclerosis, and peripheral artery diseases, while increased serum uric acid level is suggested to be independently associated with an increased risk of cardiovascular mortality. Accordingly, to investigate whether hyperuricemia is associated with serum CRP, we compared serum CRP levels between healthy subjects and patients with gout. In addition, we also examined whether benzbromarone has effects on serum CRP levels in patients with gout and the expression of CRP messenger RNA of CRP in the hepatoma cell line HuH7. METHODS: In the first experiment, 40 healthy males and 43 male patients with gout were enrolled, then blood samples were drawn from each after an overnight fast. In the second experiment, 42 male patients with gout were given uric acid-lowering therapy with benzbromarone. Blood samples were drawn after an overnight fast before and 1 year after beginning benzbromarone treatment. In the third experiment, the effects of benzbromarone on IL1beta-induced CRP expression were determined in HuH7 cells. RESULTS: Log serum CRP levels were not significantly different between the patients with gout and healthy subjects, while log serum CRP levels were decreased by 11% after benzbromarone treatment, as compared to the values before treatment (p < 0.01). In addition, log serum adiponectin levels were elevated by 2% after treatment (p < 0.01). Furthermore, our in vitro findings demonstrated that benzbromarone down-regulated IL1beta-stimulated CRP gene expression. CONCLUSIONS: These results suggest that hyperuricemia may not contribute to an increase in serum CRP level, while benzbromarone may have a favorable effect on CRP.

Reduction of whole PTH/intact PTH ratio as a predictor of bone metabolism in cinacalcet treatment of hemodialysis patients with secondary hyperparathyroidism.

UNLABELLED: In cinacalcet treatment of hemodialysis (HD) patients with secondary hyperparathyroidism (SHPT), not only intact parathyroid hormone (I-PTH), whole PTH (W-PTH), and bone markers, but also W-PTH/I-PTH ratio as proportion of active PTH(1-84) molecules were decreased. Changes in W-PTH/I-PTH ratio significantly correlated and predicted changes in bone marker. INTRODUCTION: Cinacalcet partly suppresses the secretion of PTH by enhancing PTH(1-84) degradation into N-truncated fragments. The objectives of this study is to investigate the significance of the N-truncated PTH/PTH(1-84) ratio for the prediction of the effect of cinacalcet in HD patients. METHODS: Serum parameters were measured during 12 weeks of oral cinacalcet administration at 25 mg daily in 39 HD patients with SHPT. RESULTS: Serum Ca, Pi, W-PTH, I-PTH, and W-PTH/I-PTH ratio all decreased significantly in a time-dependent manner during cinacalcet administration. Serum tartrate-resistant acid phosphatase (TRAP) 5b reflected these changes more precisely than serum N-telopeptide of type-I collagen. At 1 week, changes in I-PTH and W-PTH correlated significantly with those in serum Pi, but not Ca. Changes in serum Pi (but not Ca) and serum W-PTH also correlated significantly with changes in serum TRAP5b at both 4 and 12 weeks, while changes in serum I-PTH correlated significantly with those in serum TRAP5b only at 12 weeks. Changes in the serum W-PTH/I-PTH ratio correlated significantly with those in serum TRAP5b at both 4 and 12 weeks, and changes in serum W-PTH/I-PTH ratio at 4 weeks showed a tendency for a correlation with changes in serum TRAP5b at 12 weeks. HD patients with a reduced W-PTH/I-PTH ratio after 4 weeks had a significantly greater reduction of TRAP5b over 12 weeks. CONCLUSION: W-PTH and the W-PTH/I-PTH ratio allow estimation of the potency of cinacalcet in enhancement of PTH degradation, and thus no less reliable markers than I-PTH for reflecting cinacalcet-induced bone resorption.

Poor muscle quality rather than reduced lean body mass is responsible for the lower serum creatinine level in hemodialysis patients with diabetes mellitus.

BACKGROUND: The serum creatinine level is significantly lower in well-nourished hemodialysis patients with diabetes mellitus (DM) than in their non-DM counterparts, despite the presence of anuria in these patients. The factors associated with this finding have not been determined. PATIENTS AND METHODS: We evaluated the association of serum creatinine with handgrip strength (HGS) and lean body mass index (LMI) in a cross-sectional study of 102 DM and 208 non-DM hemodialysis patients to determine if poorer muscle quality in DM patients could explain the reduced level of serum creatinine. All the DM patients were well-nourished. Grip dynamometry and dual-energy X-ray absorptiometry (DXA) were used to measure HGS and LMI, respectively. RESULTS: The DM patients had a significantly lower serum creatinine level and HGS compared to the non-DM patients, but whole-body LMI and LMI of the upper limbs did not differ between the two groups of patients. The DM patients had significantly lower serum creatinine/whole-body LMI, serum creatinine/arm LMI, HGS/whole-body LMI, and HGS/arm LMI ratios. The serum creatinine level was significantly correlated with HGS and with whole-body and upper limb LMI in both groups of patients. However, regression analyses of LMI with serum creatinine and HGS gave significantly shallower slopes for the DM patients compared to the non-DM patients. CONCLUSION: This suggests that the muscle strength generated per unit of muscle mass, which is reflected well by the serum creatinine level, is significantly reduced in DM hemodialysis patients. Therefore, our results show that the significantly lower serum creatinine levels in DM hemodialysis patients compared to non-DM hemodialysis patients may be explained by poor muscle quality rather than by reduced muscle mass or malnutrition.

Association of increased active PTH(1-84) fraction with decreased GFR and serum Ca in predialysis CRF patients: modulation by serum 25-OH-D.

UNLABELLED: As the serum calcium and glomerular filtration rate decreased, the proportion of active PTH(1-84) molecules in PTH immunoreactivity increased in serum from predialysis uremic patients, particularly those with vitamin D insufficiency. INTRODUCTION: The PTH(1-84) fraction was altered in predialysis patients with chronic renal failure (CRF). METHODS: Serum PTH in predialysis CRF patients without any medication was measured by PTH(1-84)-specific whole PTH assay and intact PTH assay cross-reacting with N-truncated PTH. RESULTS: In CRF patients, the glomerular filtration rate (GFR) correlated positively with serum Ca and 1,25-dihydroxyvitamin D (1,25(OH)(2)D), and inversely with serum Pi, log intact PTH, and log whole PTH. In multiple regression analysis, including age, gender, body mass index, GFR, Ca, and Pi and 1,25(OH)(2)D as independent variables, serum Ca and GFR associated significantly with serum log whole PTH and intact PTH. Serum log whole PTH/intact PTH ratio, which increased as serum Ca and GFR decreased, retained a negative correlation in those with serum 25-hydroxyvitamin D levels below 20 ng/ml, but not in those above 20 ng/ml. The ratio also correlated positively with serum log tartrate-resistant acid-phosphatase-5b, log cross-linked N-telopeptide of type-I collagen, and log bone alkaline-phosphatase. CONCLUSION: As GFR declined with suppression of serum Ca, the proportion of active PTH molecules increased in predialysis CRF patients, particularly those with vitamin D insufficiency.