Kazuhide Ogino

Uric Acid-Lowering Treatment With Benzbromarone in Patients With Heart Failure A Double-Blind Placebo-Controlled Crossover Preliminary Study

Background— Hyperuricemia is common in chronic heart failure (CHF), and it is a strong independent marker of prognosis. Upregulated xanthine oxidase (XO) activity and impaired renal excretion have been shown to account for increased serum uric acid (UA) levels in CHF. Therapeutic interventions with allopurinol to reduce UA levels by XO inhibition have been shown to be beneficial. Discussions are ongoing whether UA itself is actively involved or it is a mere marker of upregulated XO activity within CHF pathophysiology. Therefore, the aim of this study was to test the effect of lowering UA by uricosuric treatment without XO inhibition on hemodynamic and metabolic characteristics of CHF. Impaired renal excretion of UA was taken into account. Methods and Results— Serum UA (SUA), urinary UA (uUA) excretion, and renal clearance test for UA (ClUA) were measured in 82 patients with CHF. SUA was significantly increased compared with controls of similar age (control, 5.45±0.70 mg/dL; New York Heart Association I, 6.48±1.70 mg/dL; New York Heart Association II, 7.34±1.94 mg/dL; New York Heart Association III, 7.61±2.11 mg/dL; P <0.01). Patients with CHF showed lower uUA excretion and ClUA. On multivariate analysis, insulin, brain natriuretic peptide ( P <0.01), and creatinine levels ( P =0.05) showed independent correlation with SUA. The treatment effect of the uricosuric agent benzbromarone was tested in 14 patients with CHF with hyperuricemia in a double-blind, placebo-controlled, randomized crossover study design. Benzbromarone significantly decreased SUA ( P <0.01). Brain natriuretic peptide, left ventricular ejection fraction, and dimensions in echocardiographic assessment did not change after benzbromarone therapy. In contrast, fasting insulin (placebo, 18.8±8.9 μU/mL; benzbromarone, 11.0±6.2 μU/mL; P <0.05), homeostasis model assessment of insulin resistance index (placebo, 5.4±2.6; benzbromarone, 3.0±1.7; P <0.05), and tumor necrosis factor-α (placebo, 2.59±0.63 pg/mL; benzbromarone, 2.14±0.51 pg/mL; P <0.05) improved after benzbromarone, and the changes in tumor necrosis factor-α levels were correlated with reduction of SUA ( P <0.05). Conclusions— These results show that UA lowering without XO inhibition may not have an effect on hemodynamic impairment in CHF pathophysiology. To the extent that these data are correct, this finding suggests that upregulated XO activity rather than UA itself is actively involved in hemodynamic impairment in CHF. Clinical Trial Registration— clinical trials.gov. Identifier: [NCT00422318][1]. Received March 26, 2009; accepted November 3, 2009. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00422318&atom=%2Fcirchf%2F3%2F1%2F73.atomBackground—Hyperuricemia is common in chronic heart failure (CHF), and it is a strong independent marker of prognosis. Upregulated xanthine oxidase (XO) activity and impaired renal excretion have been shown to account for increased serum uric acid (UA) levels in CHF. Therapeutic interventions with allopurinol to reduce UA levels by XO inhibition have been shown to be beneficial. Discussions are ongoing whether UA itself is actively involved or it is a mere marker of upregulated XO activity within CHF pathophysiology. Therefore, the aim of this study was to test the effect of lowering UA by uricosuric treatment without XO inhibition on hemodynamic and metabolic characteristics of CHF. Impaired renal excretion of UA was taken into account. Methods and Results—Serum UA (SUA), urinary UA (uUA) excretion, and renal clearance test for UA (ClUA) were measured in 82 patients with CHF. SUA was significantly increased compared with controls of similar age (control, 5.45±0.70 mg/dL; New York Heart Association I, 6.48±1.70 mg/dL; New York Heart Association II, 7.34±1.94 mg/dL; New York Heart Association III, 7.61±2.11 mg/dL; P<0.01). Patients with CHF showed lower uUA excretion and ClUA. On multivariate analysis, insulin, brain natriuretic peptide (P<0.01), and creatinine levels (P=0.05) showed independent correlation with SUA. The treatment effect of the uricosuric agent benzbromarone was tested in 14 patients with CHF with hyperuricemia in a double-blind, placebo-controlled, randomized crossover study design. Benzbromarone significantly decreased SUA (P<0.01). Brain natriuretic peptide, left ventricular ejection fraction, and dimensions in echocardiographic assessment did not change after benzbromarone therapy. In contrast, fasting insulin (placebo, 18.8±8.9 &mgr;U/mL; benzbromarone, 11.0±6.2 &mgr;U/mL; P<0.05), homeostasis model assessment of insulin resistance index (placebo, 5.4±2.6; benzbromarone, 3.0±1.7; P<0.05), and tumor necrosis factor-&agr; (placebo, 2.59±0.63 pg/mL; benzbromarone, 2.14±0.51 pg/mL; P<0.05) improved after benzbromarone, and the changes in tumor necrosis factor-&agr; levels were correlated with reduction of SUA (P<0.05). Conclusions—These results show that UA lowering without XO inhibition may not have an effect on hemodynamic impairment in CHF pathophysiology. To the extent that these data are correct, this finding suggests that upregulated XO activity rather than UA itself is actively involved in hemodynamic impairment in CHF. Clinical Trial Registration—clinicaltrials.gov. Identifier: NCT00422318.

Uric Acid-Lowering Treatment With Benzbromarone in Patients With Heart FailureCLINICAL PERSPECTIVE

Background— Hyperuricemia is common in chronic heart failure (CHF), and it is a strong independent marker of prognosis. Upregulated xanthine oxidase (XO) activity and impaired renal excretion have been shown to account for increased serum uric acid (UA) levels in CHF. Therapeutic interventions with allopurinol to reduce UA levels by XO inhibition have been shown to be beneficial. Discussions are ongoing whether UA itself is actively involved or it is a mere marker of upregulated XO activity within CHF pathophysiology. Therefore, the aim of this study was to test the effect of lowering UA by uricosuric treatment without XO inhibition on hemodynamic and metabolic characteristics of CHF. Impaired renal excretion of UA was taken into account. Methods and Results— Serum UA (SUA), urinary UA (uUA) excretion, and renal clearance test for UA (ClUA) were measured in 82 patients with CHF. SUA was significantly increased compared with controls of similar age (control, 5.45±0.70 mg/dL; New York Heart Association I, 6.48±1.70 mg/dL; New York Heart Association II, 7.34±1.94 mg/dL; New York Heart Association III, 7.61±2.11 mg/dL; P <0.01). Patients with CHF showed lower uUA excretion and ClUA. On multivariate analysis, insulin, brain natriuretic peptide ( P <0.01), and creatinine levels ( P =0.05) showed independent correlation with SUA. The treatment effect of the uricosuric agent benzbromarone was tested in 14 patients with CHF with hyperuricemia in a double-blind, placebo-controlled, randomized crossover study design. Benzbromarone significantly decreased SUA ( P <0.01). Brain natriuretic peptide, left ventricular ejection fraction, and dimensions in echocardiographic assessment did not change after benzbromarone therapy. In contrast, fasting insulin (placebo, 18.8±8.9 μU/mL; benzbromarone, 11.0±6.2 μU/mL; P <0.05), homeostasis model assessment of insulin resistance index (placebo, 5.4±2.6; benzbromarone, 3.0±1.7; P <0.05), and tumor necrosis factor-α (placebo, 2.59±0.63 pg/mL; benzbromarone, 2.14±0.51 pg/mL; P <0.05) improved after benzbromarone, and the changes in tumor necrosis factor-α levels were correlated with reduction of SUA ( P <0.05). Conclusions— These results show that UA lowering without XO inhibition may not have an effect on hemodynamic impairment in CHF pathophysiology. To the extent that these data are correct, this finding suggests that upregulated XO activity rather than UA itself is actively involved in hemodynamic impairment in CHF. Clinical Trial Registration— clinical trials.gov. Identifier: [NCT00422318][1]. Received March 26, 2009; accepted November 3, 2009. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00422318&atom=%2Fcirchf%2F3%2F1%2F73.atomBackground—Hyperuricemia is common in chronic heart failure (CHF), and it is a strong independent marker of prognosis. Upregulated xanthine oxidase (XO) activity and impaired renal excretion have been shown to account for increased serum uric acid (UA) levels in CHF. Therapeutic interventions with allopurinol to reduce UA levels by XO inhibition have been shown to be beneficial. Discussions are ongoing whether UA itself is actively involved or it is a mere marker of upregulated XO activity within CHF pathophysiology. Therefore, the aim of this study was to test the effect of lowering UA by uricosuric treatment without XO inhibition on hemodynamic and metabolic characteristics of CHF. Impaired renal excretion of UA was taken into account. Methods and Results—Serum UA (SUA), urinary UA (uUA) excretion, and renal clearance test for UA (ClUA) were measured in 82 patients with CHF. SUA was significantly increased compared with controls of similar age (control, 5.45±0.70 mg/dL; New York Heart Association I, 6.48±1.70 mg/dL; New York Heart Association II, 7.34±1.94 mg/dL; New York Heart Association III, 7.61±2.11 mg/dL; P<0.01). Patients with CHF showed lower uUA excretion and ClUA. On multivariate analysis, insulin, brain natriuretic peptide (P<0.01), and creatinine levels (P=0.05) showed independent correlation with SUA. The treatment effect of the uricosuric agent benzbromarone was tested in 14 patients with CHF with hyperuricemia in a double-blind, placebo-controlled, randomized crossover study design. Benzbromarone significantly decreased SUA (P<0.01). Brain natriuretic peptide, left ventricular ejection fraction, and dimensions in echocardiographic assessment did not change after benzbromarone therapy. In contrast, fasting insulin (placebo, 18.8±8.9 &mgr;U/mL; benzbromarone, 11.0±6.2 &mgr;U/mL; P<0.05), homeostasis model assessment of insulin resistance index (placebo, 5.4±2.6; benzbromarone, 3.0±1.7; P<0.05), and tumor necrosis factor-&agr; (placebo, 2.59±0.63 pg/mL; benzbromarone, 2.14±0.51 pg/mL; P<0.05) improved after benzbromarone, and the changes in tumor necrosis factor-&agr; levels were correlated with reduction of SUA (P<0.05). Conclusions—These results show that UA lowering without XO inhibition may not have an effect on hemodynamic impairment in CHF pathophysiology. To the extent that these data are correct, this finding suggests that upregulated XO activity rather than UA itself is actively involved in hemodynamic impairment in CHF. Clinical Trial Registration—clinicaltrials.gov. Identifier: NCT00422318.

Cause of Persistent Hypouricemia in Outpatients

We measured serum urate in 3,258 Japanese outpatients. Five of them had persistent hypouricemia. Three also had microhematuria. Four of the five patients were proven to have renal uricosuria with hypouricemia, but otherwise normal tubular function. When tested with both pyrazinamide and benzbromarone, 1 patient had a presecretory reabsorption defect, 2 had postabsorption defects, and 1 an enhanced renal tubular secretion of urate. These results suggest that persistent hypouricemia in outpatients is of very low incidence, is usually caused by an isolated metabolic error of urate transport, and is not related to drug ingestion or systemic disease.

Interleukin-6 and tumor necrosis factor-α levels increase in response to maximal exercise in patients with chronic heart failure

Abstract Chronic heart failure (CHF) is characterized by the activation of neurohormones and cytokines. Strenuous exercise causes activation of both systems but the effect of acute bouts of exercise on cytokines is not known in patients with CHF. This study determined whether maximal exercise induces activation of cytokines in CHF. Plasma interleukin-6 (IL-6), tumor necrosis factor (TNF)-α, epinephrine, norepinephrine, and atrial and brain natriuretic peptides (ANP and BNP) were determined before and after symptom-limited cardiopulmonary exercise testing in 80 patients with CHF (LVEF=38±1%, peak V O 2 =18.8±0.5 ml/min/kg) and age-matched 33 controls. Resting IL-6 (Controls vs. CHF: 1.3±0.2 vs. 2.5±0.3 pg/ml, P P r =0.34 and r =0.35, respectively) with logplasma norepinephrine, and were negatively correlated ( r =−0.39 and r =−0.32, respectively) with peak V O 2 . Maximal exercise increased IL-6 and TNF-α both in controls and CHF (all P r =0.63, P r =0.57, P =0.0006) in controls, but not in CHF. ΔTNF-α correlated with ΔANP ( r =0.28, P =0.01) only in CHF. In summary, cytokine activation at rest was associated with high plasma norepinephrine and exercise intolerance. Maximal exercise caused increases in IL-6 and TNF-α concentrations. Sympathetic activation seems to be important for the IL-6 increase during exercise in controls. In CHF, changes in ANP during exercise were associated with the exercise-induced increase in TNF-α, but still unknown mechanisms are involved for the cytokine activation during exercise.

Augmented response in plasma brain natriuretic peptide to dynamic exercise in patients with left ventricular dysfunction and congestive heart failure

Abstract. Kato M, Kinugawa T, Ogino K, Endo A, Osaki S, Igawa O, Hisatome I, Shigemasa C (Tottori University Faculty of Medicine, Yonago, Japan). Augmented response in plasma brain natriuretic peptide to dynamic exercise in patients with left ventricular dysfunction and congestive heart failure. J Intern Med 2000; 248: 309–315.

Mitochondrial DNA deletion associated with the reduction of adenine nucleotides in human atrium and atrial fibrillation

Background Structural changes in the number, size, and shape of mitochondria (mt) have been observed in the atrial muscles of patients with atrial fibrillation (AF) and of animals with rapid atrial pacing, however, it is not known whether the mitochondrial function is impaired in human atrium with AF.

Protective effect of edaravone against hypoxia-reoxygenation injury in rabbit cardiomyocytes.

We examined whether edaravone (Eda), a clinically available radical scavenger, directly protects cardiomyocytes from ischemia/reperfusion (I/R) injury, and whether the timing of its application is critical for protection. Cardioprotective effects of edaravone were tested in the modified cell‐pelleting model of ischemia and under exogenous oxidative stress (hydrogen peroxide: H2O2) in isolated adult rabbit ventricular cells. Cell death and reactive oxygen species (ROS) generation were detected using propidium iodide (PI) and DCFH‐DA, respectively. These parameters were evaluated objectively using flow cytometory. Hypoxia and reoxygenation aggravated the proportion of dead cells from 32.2±1.8% (Baseline) to 51.3±2.7% (Control). When 15 μM edaravone was applied either throughout the entire experiment (Through) or only at reoxygenation (Reox), cell death was significantly reduced to 39.9±1.8% (P<0.01 vs Control) and 43.3±2.5% (P<0.05 vs Control), respectively. In contrast, when edaravone was applied 10 min after reoxygenation, its protective effect disappeared. Cardioprotection by edaravone was more remarkable than that afforded by other free radical scavengers, such as ascorbate and superoxide dismutase (SOD). There is a positive correlation between the cardioprotective effect of edaravone and the extent of ROS reduction. Edaravone blunted the H2O2‐induced changes in electrical properties, and significantly prolonged the time to contracture induced by H2O2 in single ventricular myocytes. Taken together, edaravone directly protects cardiomyocytes from I/R injury by attenuating ROS production, even when applied at the time of reoxygenation, suggesting that edaravone could be a potent cardioprotective therapeutic agent against hypoxia–reoxygenation injury.

Allopurinol Reduces Neointimal Hyperplasia in the Carotid Artery Ligation Model in Spontaneously Hypertensive Rats

Uric acid and oxidative stress promote cardiovascular diseases, including atherosclerosis and hypertension. Xanthine oxidase, through which uric acid is generated, is a free-radical generating enzyme. The aim of the current study was to investigate whether allopurinol, an inhibitor of xanthine oxidase activity, affects vascular remodeling and vascular smooth muscle cell (VSMC) proliferation. In the carotid artery ligation model using spontaneously hypertensive rats (SHR), treatment with allopurinol induced a reduction in the neointima/media ratio by 27% (38.5±34.3% in the control group and 28.1±20.8% in the allopurinol-treated group, respectively, p<0.01) without alterations in vascular circumference at 3 weeks after ligation when compared to the control. Allopurinol lowered the serum uric acid concentration (147.0±3.6 μmol/l in the control group and 16.1±3.6 μmol/l in the allopurinol-treated group, respectively p<0.01) and xanthine oxidase activity, but not the blood pressure. In an in vitro study, high concentrations of uric acid (100 and 200 μmol/l) stimulated VSMC growth, but there was no stimulation of these cells by a low concentration of uric acid (50 μmol/l) or by any of three concentrations of xanthine (50, 100 and 200 μmol/l). In addition, allopurinol (5 μmol/l) had no effect on the cell growth. In conclusion, uric acid is a potent stimulator of VSMC proliferation, and allopurinol prevented vascular remodeling in SHR at least in part by inhibiting uric acid concentration.

Depletion of Uric Acid Due to SLC22A12 (URAT1) Loss-of-Function Mutation Causes Endothelial Dysfunction in Hypouricemia

BACKGROUND Uric acid (UA) serves as an antioxidant in vascular endothelial cells. UA transporter 1 (URAT1) encoded by SLC22A12 is expressed in the kidney and vessels and its loss of function causes hypouricemia. The purpose of this study was to examine whether there is any endothelial dysfunction in patients with hypouricemia. METHODS AND RESULTS Twenty-six patients with hypouricemia (<2.5 mg/dl) and 13 healthy control subjects were enrolled. Endothelial function was evaluated using flow-mediated dilation (FMD). mRNA of UA transporters expressed in cultured human umbilical endothelial cells (HUVEC) was detected on RT-PCR. There was a positive correlation between FMD and serum UA in the hypouricemia group. URAT1 loss-of-function mutations were found in the genome of 21 of 26 patients with hypouricemia, and not in the other 5. In the hypouricemia groups, serum UA in homozygous and compound heterozygous patients was significantly lower than in other groups, suggesting that severity of URAT1 dysfunction may influence the severity of hypouricemia. Thirteen of 16 hypouricemia subjects with homozygous and compound heterozygote mutations had SUA <0.8 mg/dl and their FMD was lower than in other groups. HUVEC do not express mRNA of URAT1, suggesting the null role of URAT1 in endothelial function. CONCLUSIONS Depletion of UA due to SLC22A12/URAT1 loss-of-function mutations causes endothelial dysfunction in hypouricemia patients.

Catecholamines, Renin-Angiotensin-Aldosterone System, and Atrial Natriuretic Peptide at Rest and During Submaximal Exercise in Patients With Congestive Heart Failure

The aim of this study was to determine the responses of plasma catecholamines, renin-angiotensin-aldosterone (RAA) activity, and plasma atrial natriuretic peptide (ANP) to exercise in patients with congestive heart failure (CHF). Cardiac and neurohormonal responses were assessed during submaximal treadmill exercise testing in 23 patients with CHF (New York Heart Association classes I-III) and 13 control subjects (without CHF). Plasma norepinephrine, epinephrine, renin activity (PRA), angiotensin II (ATII), aldosterone, and ANP were measured at rest and immediately after exercise. Exercise duration was shorter in patients with CHF (control, 10.4 +/- 0.9 minute; CHF, 6.2 +/- 0.7 minute; P < 0.01). Heart rate and blood pressure responses were similar except for the smaller peak heart rate (control, 145 +/- 5 beats per minute; CHF, 129 +/- 4 beats per minute; P < 0.05) and higher systolic blood pressure at recovery stage (control, 122 +/- 4 mm Hg; CHF, 142 +/- 4 mm Hg; P < 0.01) in patients with CHF. At rest, plasma norepinephrine levels were insignificantly higher in patients with CHF (control, 110 +/- 10 pg/mL; CHF, 170 +/- 26 pg/mL; P = 0.09), and ANP levels (control, 40 +/- 5 pg/mL; CHF, 94 +/- 17 pg/mL; P < 0.05) and PRA levels (control, 0.77 +/- 0.11 ng/mL/hr; CHF, 4.33 +/- 1.25 ng/mL/hr; P < 0.05) were significantly higher. There were no differences in peak norepinephrine, epinephrine, or ANP between the two groups. Angiotensin II and aldosterone levels were similar between the two groups, although, in patients with CHF, there was a trend toward higher levels of ATII while at rest (control, 12.4 +/- 1.4 pg/mL; CHF, 20.3 +/- 3.3 pg/mL; P = 0.08) and at peak (control, 20.5 +/- 1.8 pg/mL; CHF, 41.0 +/- 9.4 pg/mL; P = 0.10). Peak values of PRA, ATII, and aldosterone positively correlated with respective resting values of PRA (r = 0.88 ng/mL/hr, P < 0.01), ATII (r = 0.63 pg/mL, P < 0.01), and aldosterone (r = 0.99, P < 0.01). Peak norepinephrine and peak ANP also positively correlated with respective resting values of norepinephrine (r = 0.58 pg/mL, P < 0.05) and ANP (r = 0.94, P < 0.01). Analysis of these results showed that patients with CHF had significantly higher levels of PRA and ANP at rest, and a trend toward augmentation in RAA system activity during exercise with less exercise workload. Basal level of neurohormones seemed to be an important determinant for the degree of exercise-induced neurohormonal activation in patients with CHF.