Chiaki Shigemasa

Human organic cation transporter (OCT1 and OCT2) gene polymorphisms and therapeutic effects of metformin

AbstractOrganic cation transporters (OCTs) are responsible for the hepatic and renal transport of metformin. In this study we analyzed variants of OCT1 and OCT2 genes in 33 patients (24 responders and nine non-responders) based on the hypothesis that polymorphisms in both genes contribute to large inter-patient variability in the clinical efficacy of metformin. The sequences of the 5′-flanking and coding regions of the two genes of interest were screened by single-strand conformation polymorphism (SSCP) analysis. To compare the causative factors between responders and non-responders, we performed stepwise discriminant functional analysis. Age, body mass index (BMI) and treatment with lipid-lowering agents were demonstrated as positive predictors, and two mutations in the OCT1 gene, −43T > G in intron 1 and 408Met > Val (1222A > G) in exon 7, were negative and positive predictors, respectively, for the efficacy of metformin; the predictive accuracy was 55.5% (P < 0.05). Subsequent study indicated that OCT1 mRNA levels tended to be lower in human livers with the 408Met (1222A) variant, though the differences did not reach the level of significance. In this study it is suggested that OCT1 and OCT2 gene polymorphisms have little contribution to the clinical efficacy of metformin.

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.

Appropriate Use of Nasal Continuous Positive Airway Pressure Decreases Elevated C-Reactive Protein in Patients With Obstructive Sleep Apnea

BACKGROUND C-reactive protein (CRP) is an important risk factor for cardiovascular disease. Furthermore, it has been reported that levels of CRP are increased in patients with obstructive sleep apnea (OSA). The aim of this study was to examine the effects of long-term therapy with nasal continuous positive airway pressure (nCPAP) on CRP levels and to investigate whether compliance with nCPAP therapy more effectively attenuated markers of systemic inflammation in patients with OSA. METHODS AND RESULTS Fifty-five patients (mean [+/- SEM] age, 55 +/- 2 years; 44 male patients, 11 female patients) with newly diagnosed moderate-to-severe OSA (apnea-hypopnea index > 20 events/h) were studied before and after 6 months of nCPAP treatment. There was a significant reduction in CRP levels after nCPAP therapy (before nCPAP therapy, 0.23 +/- 0.03 mg/dL; after nCPAP therapy, 0.17 +/- 0.02 mg/dL; p < 0.01). Additionally, we divided these patients into two groups based on adherence to nCPAP therapy. A group of patients using nCPAP > 4 h/d and > 5 d/wk were designated as the good compliance group. The decrease in CRP concentration was significant (before nCPAP therapy, 0.23 +/- 0.04 mg/dL; after nCPAP therapy, 0.16 +/- 0.03 mg/dL; p < 0.05) in the good compliance group but not in the poor compliance group (before nCPAP therapy, 0.24 +/- 0.05 mg/dL; after nCPAP therapy, 0.20 +/- 0.05 mg/dL; p = 0.21). Furthermore, we divided those patients into a high CRP group (>/= 0.2 mg/dL) and a normal CRP group (< 0.2 mg/dL) before nCPAP therapy. The significant decrease in CRP levels in the good compliance group was evident only in those patients with an initially elevated CRP level (before nCPAP therapy, 0.48 +/- 0.08 mg/dL; after nCPAP therapy, 0.29 +/- 0.06 mg/dL; p < 0.05). CONCLUSION Appropriate use of nCPAP in patients with OSA may be required to decrease elevated CRP levels, with possible implications for cardiovascular morbidity and mortality.

Evaluation of changes in sympathetic nerve activity and heart rate in essential hypertensive patients induced by amlodipine and nifedipine

Objective To compare the effects of amlodipine and nifedipine on heart rate and parameters of sympathetic nerve activity during the acute and chronic treatment periods in order to elucidate their influence on cardiovascular outcome. Design A randomized and single-blind study. Methods We performed 24 h ambulatory electrocardiography and blood pressure monitoring of 45 essential hypertensive inpatients. Plasma and urinary catecholamine levels were measured during the control (pretreatment) period, on the first day (acute period) and after 4 weeks (chronic period) of administration of amlodipine and of short-acting nifedipine or its slow-releasing formulation. The low-frequency and high-frequency power spectral densities and low-frequency: high-frequency ratio were obtained by heart rate power spectral analysis. Results Blood pressure was significantly and similarly reduced by administrations of amlodipine, short-acting nifedipine and slow-releasing nifedipine during the chronic period. The total QRS count per 24 h, which remained constant during the chronic period of administration of slow-releasing nifedipine and was increased by administration of nifedipine, was decreased by 2.8% by administration of amlodipine. Administration of amlodipine decreased the plasma and urinary norepinephrine levels during the chronic period, whereas the levels were significantly increased by administration of short-acting nifedipine and not changed by administration of slow-release nifedipine. Although low-frequency: high-frequency ratio was increased significantly by administration of short-acting nifedipine and slightly by administration of slow-releasing nifedipine, administration of amlodipine reduced it during the acute and chronic periods. Conclusions Administration of amlodipine did not induce an increase in sympathetic nerve activity in essential hypertensive patients during the chronic period, suggesting that beneficial effects on essential hypertension can be expected after its long-term administration. Administration of slow-releasing nifedipine induces milder reflex sympathetic activation than does that of short-acting nifedipine.

Pharmacogenetic determinants of variability in lipid-lowering response to pravastatin therapy

AbstractPravastatin is mainly taken up from the circulation into the liver via organic anion-transporting polypeptide 1B1 (SLCO1B1 gene product). We examined the contribution of genetic variants in the SLCO1B1 gene and other candidate genes to the variability of pravastatin efficacy in 33 hypercholesterolemic patients. In the initial phase of pravastatin treatment (8 weeks), heterozygous carriers of the SLCO1B1*15 allele had poor low-density lipoprotein cholesterol (LDL-C) reduction relative to non-carriers (percent reduction: −14.1 vs −28.9%); however, the genotype-dependent difference in the cholesterol-lowering effect disappeared after 1 year of treatment. Cholesterol 7α-hydroxylase (CYP7A1) and apolipoprotein E (APOE) are known to contribute to lipid metabolism. Homozygous carriers of the CYP7A1 -204C allele or heterozygotes for both CYP7A1 -204C and APOE ε4 alleles showed significantly poorer LDL-C reduction compared to that in other genotypic groups after 1 year of treatment (−24.3 vs −33.1%). These results suggest that the SLCO1B1*15 allele is associated with a slow response to pravastatin therapy, and the combined genotyping of CYP7A1 and APOE genes is a useful index of the lipid-lowering effect of pravastatin.

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.

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.

Age-related BM-MNC dysfunction hampers neovascularization.

Although ischemia-induced neovascularization is reportedly impaired with aging, the effect of aged-bone marrow mononuclear cells (BM-MNCs) on neovascularization has not been investigated. The neovascularization capacity of BM-MNCs obtained from 8-week-old mice (young) was compared to those obtained from 18-month-old mice (old), both in vivo and in vitro. Neovascularization in ischemic limbs was significantly impaired in old mice. Whereas transplantation of young BM-MNCs significantly improved blood perfusion, tissue capillary density, and vascular endothelial growth factor (VEGF) production in transplanted ischemic limbs, no such effects were observed with old BM-MNCs. Old BM-MNCs also showed a significant impairment of in vitro VEGF production and migratory capacity in response to VEGF. The number of Dil/lectin-positive cells was significantly lower in old mice, but there was no difference in the number of AC133(+)/CD34(+) and CD34(+)/VEGF-R2(+) positive cells between young and old BM-MNCs. Transplantation of young BM-MNCs improved neovascularization and VEGF production in the ischemic limbs of old recipients, with results that were similar to those obtained in young recipients. These results indicate that the neovascularization capacity of transplanted BM-MNCs is impaired with aging. However, aging does not hamper the revitalization of neovascularization in the murine host in response to transplantation of young BM-MNCs.