Kenichiro Arakawa

Diagnostic Use of Serum Deoxyribonuclease I Activity as a Novel Early-Phase Marker in Acute Myocardial Infarction

Background—The delayed release of serum cardiac markers such as creatine kinase isoenzyme MB and equivocal early electrocardiographic changes have hampered a diagnosis of acute myocardial infarction (AMI) in the early phase after its onset. Therefore, a reliable serum biochemical marker for the diagnosis of AMI in the very early phase is desirable. Methods and Results—Serum samples were collected from the patients with AMI, unstable angina pectoris, stable angina pectoris, and other diseases. Levels of serum deoxyribonuclease I (DNase I) activity in the patients were determined. An abrupt elevation of serum DNase I activity was observed within approximately 3 hours of the onset of symptoms in patients with AMI, with significantly higher activity levels (21.7±5.10 U/L) in this group compared with the other groups with unstable angina pectoris (10.4±4.41 U/L), angina pectoris (10.8±3.70 U/L), and other diseases (9.22±4.16 U/L). Levels of the DNase I activity in serum then exhibited a marked time-dependent decline within 12 hours and had returned to basal levels within 24 hours. Conclusions—We suggest that serum DNase I activity could be used as a new diagnostic marker for the early detection of AMI.

PET imaging of redox and energy states in stroke-like episodes of MELAS

In stroke-like episodes of patients with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS), changes in oxidative stress and glucose metabolism and their sequence remain obscure. We developed a novel double imaging method using positron emission tomography (PET) with [(62)Cu]-diacetyl-bis(N4-methylthiosemicarbazone) ((62)Cu-ATSM) and [(18)F]-fluorodeoxyglucose ((18)FDG) to visualize the regional oxidative stress, glucose metabolism and blood flow in brain lesions of stroke-like episodes non-invasively and rapidly. These PET imagings were performed on a MELAS patient with stroke-like lesions, and clearly demonstrated that oxidative stress following hyperemia along with increased glucose metabolism plays crucial roles in the pathogenesis of MELAS stroke-like episodes.

A new-generation N/L-type calcium channel blocker leads to less activation of the renin-angiotensin system compared with conventional L type calcium channel blocker.

Objective Calcium channel blocker (CCB) is one of the most useful antihypertensive agents. However, the activation of the renin–angiotensin system (RAS) is an unfavorable characteristic. N-type calcium channel is thought to be involved in catecholamines release. Accordingly, N/L-type CCB has a probability of less activation of the RAS. We substantiated the hypothesis that N/L-type CCB, cilnidipine, leads to less activation of the RAS compared with conventional L-type CCB, amlodipine. Design Randomized, cross-over study. Setting Outpatient study. Participants Participants were 110 hypertensive patients [male/female 46/64, age 66.3 ± 10.8 years, systolic blood pressure (SBP)/diastolic blood pressure (DBP) 161.8 ± 16.9/92.9 ± 12.4 mmHg, s-Cr 0.77 ± 0.32 mg/dl, plasma renin activity (PRA) 0.65 ± 0.63 ng/ml per h, angiotensin I (AngI) 70.5 ± 77.3 pg/ml, angiotensin II (AngII) 5.2 ± 3.9 pg/ml, plasma aldosterone concentration (PAC) 76.3 ± 35.9 pg/ml, urinary albumin excretion (UAE) 108.1 ± 284.2 mg/gCr]. Amlodipine besilate or cilnidipine was administered for 12 weeks in a cross-over manner as a monotherapy with an intention-to-treat fashion by titrating doses. Final doses of amlodipine besilate and cilnidipine were 6.6 ± 2.7 and 13.7 ± 5.1 mg/day, respectively. Main outcome measures Changes in blood pressure, PRA, AngI, AngII, PAC, UAE of baseline and each end of amlodipine besilate and cilnidipine administration. Results Results were as follows (amlodipine vs. cilnidipine): SBP/DBP (mmHg): 135.2 ± 11.7/79.8 ± 9.6 vs. 136.7 ± 13.2/79.5 ± 10.9, P = 0.22/0.74; PRA (ng/ml per h): 1.16 ± 1.03 vs. 0.95 ± 0.78, P < 0.01; AngI (pg/ml): 155.0 ± 306.4 vs. 101.8 ± 92.0, P < 0.05; AngII (pg/ml): 12.0 ± 12.3 vs. 7.1 ± 4.5, P < 0.001; PAC (pg/ml): 81.6 ± 37.9 vs. 74.3 ± 36.2, P < 0.05; UAE (mg/gCr): 145.4 ± 424.5 vs. 58.8 ± 125.1, P < 0.05. Thus, in spite of the comparable blood pressure reductions, each level of components of the RAS at cilnidipine administration was significantly lower than those at amlodipine. Apart from this, UAE at cilnidipine administration was also significantly lower than that at amlodipine. Conclusion It is suggested that cilnidipine leads to less activation of the RAS compared with amlodipine for the first time in human clinical patients and therefore cilnidipine might be expected to be superior in organ protection in addition to the antialbuminuric effect.

Synergy of aldosterone and high salt induces vascular smooth muscle hypertrophy through up-regulation of NOX1.

Aldosterone and excessive salt intake are obviously implicated in human arteriosclerosis. Aldosterone activates NADPH oxidase that induces superoxide production and cardiovascular cell hypertrophy. The activity of NADPH oxidase is influenced by the expression of its subunit, through which, vasoactive agents activate in the enzyme. Here, we show that aldosterone elicited overexpression of the NOX1 catalytic subunit of NADPH oxidase in the presence of high salt in A7r5 vascular smooth muscle cells. We also showed that NOX1 is a key subunit involved in physiological aldosterone-induced NADPH oxidase activation. Aldosterone dose-dependently increased NOX1 expression and NADPH activity, which subsequently caused superoxide over-production and A7r5 cell hypertrophy. However, aldosterone had little effect on any of NOX1, superoxide over-production and cell hypertrophy in NOX1 knock-down A7r5 cells. These results suggest that the aldosterone-induced effects are mainly generated through NOX1. Aldosterone-induced NOX1 over-expression was augmented by 145 mM sodium chloride, as compared with control medium containing 135 mM NaCl. However, NOX1 over-expression was not induced in the absence of aldosterone, even in the presence of 185 mM NaCl. The mineralocorticoid receptor antagonist, eplerenone, completely abolished NOX1 over-expression, indicating that aldosterone is essential for this process.

In vivo functional brain imaging and a therapeutic trial of L-arginine in MELAS patients.

BACKGROUND Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is the most common type of mitochondrial disease and is characterized by stroke-like episodes (SEs), myopathy, lactic acidosis, diabetes mellitus, hearing-loss and cardiomyopathy. The causal hypotheses for SEs in MELAS presented to date are angiopathy, cytopathy and neuronal hyperexcitability. L-arginine (Arg) has been applied for the therapy in MELAS patients. SCOPE OF REVIEW We will introduce novel in vivo functional brain imaging techniques such as MRI and PET, and discuss the pathogenesis of SEs in MELAS patients. We will further describe here our clinical experience with L-arg therapy and discuss the dual pharmaceutical effects of this drug on MELAS. MAJOR CONCLUSIONS Administration of L-arg to MELAS patients has been successful in reducing neurological symptoms due to acute strokes and preventing recurrences of SEs in the chronic phase. L-Arg has dual pharmaceutical effects on both angiopathy and cytopathy in MELAS. GENERAL SIGNIFICANCE In vivo functional brain imaging promotes a better understanding of the pathogenesis and potential therapies for MELAS patients. This article is part of a Special Issue entitled Biochemistry of Mitochondria, Life and Intervention 2010.

Aldosterone inhibits endothelial morphogenesis and angiogenesis through the downregulation of vascular endothelial growth factor receptor-2 expression subsequent to peroxisome proliferator-activated receptor gamma

Angiogenesis plays a pivotal role in cardiovascular diseases such as ischemic heart disease, limb ischemia and heart failure, and has recently been shown to mediate various biological activities related to the pathogenesis of these diseases. In the present study, we evaluated the role of aldosterone in angiogenesis. Tube formation assay on Matrigel using human umbilical vein endothelial cells (HUVEC) revealed that aldosterone inhibited endothelial morphogenesis in a manner sensitive to eplerenone, a selective mineralocorticoid receptor antagonist. The anti-angiogenic effect of aldosterone was further confirmed by an in vivo angiogenesis assay using a Matrigel plug model in mice. Reverse transcription-mediated polymerase chain reaction and immunoblotting demonstrated that aldosterone downregulated the expression levels of vascular endothelial growth factor receptor-2 (VEGFR-2) and peroxisome proliferators-activated receptor gamma (PPAR gamma). VEGFR-2 expression was found to be enhanced in response to PPAR gamma activation by troglitazone, and attenuated by GW9662, a specific antagonist of PPAR gamma. In the tube formation assay, endothelial morphogenesis was stimulated by troglitazone, and inhibited by GW9662, indicating that PPAR gamma activation mediates positive regulation of angiogenesis through enhancement of VEGFR-2 expression. These data suggest that aldosterone inhibits angiogenesis through VEGFR-2 downregulation, subsequent to, at least in part, attenuation of PPAR gamma expression. The present findings provide a new insight into the possible therapeutic application of mineralocorticoid receptor blockade to various cardiovascular diseases.

Effects of Combination Therapy With Olmesartan and Azelnidipine on Serum Osteoprotegerin in Patients With Hypertension

Background: Vascular calcification is a potent predictor of plaque instability and cardiac events. Osteoprotegerin (OPG), well-known vascular calcification mediator, is a signaling molecule involved in bone remodeling, which has been implicated in the regulation of vascular calcification and atherogenesis. The purpose of this study was to compare the combination treatments of olmesartan/azelnidipine and olmesartan/diuretics on serum bone-related markers in patients with essential hypertension. Methods and Results: A total of 48 patients with hypertension treated with 20 mg olmesartan were randomized to receive combination treatment with 16 mg azelnidipine (O/A group) or diuretics (1 mg indapamide; O/D group) for 12 months. Osteoprotegerin, matrix metalloproteinase 2 (MMP-2), and high-sensitive CRP (hs-CRP) were measured after 3 and 12 months of treatment. Cardio-ankle vascular index (CAVI) was measured as the arterial stiffness using a VaSera CAVI instrument at the same time points. In both groups, the systolic and diastolic blood pressure reduction is similar. Serum OPG, MMP-2, and hs-CRP were significantly decreased at 12 months in the O/A group (P < .05), while there were no significant reductions in the O/D group. CAVI was significantly improved at 12 months in both the treatment groups. The improvement in CAVI was significantly greater in the O/A group than in the O/D group. Conclusion: Azelnidipine, but not indapamide, combined with olmesartan, improved arterial stiffness and were associated with significant decrease in OPG, MMP-2, and hs-CRP concentrations. These results suggest that the beneficial effects of the combination treatments of olmesartan/azelnidipine on arterial stiffness are mediated by alteration in bone-remodeling and inflammatory markers.

Evaluation of Systemic Redox States in Patients Carrying the MELAS A3243G Mutation in Mitochondrial DNA

Background/Aims: To clarify the change of systemic redox states in patients carrying the A3243G mutation in mitochondrial DNA (A3243G), we evaluated oxidative stress and antioxidant activity in the serum of patients. Methods: Oxidative stress and antioxidant activity in the serum samples obtained from 14 patients carrying A3243G and from 34 healthy controls were analyzed using the diacron-reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP) tests, respectively. Results: The mean d-ROMs level of all patients was significantly greater than that of the controls (p < 0.005), and the mean BAP/d-ROMs ratio of all patients was significantly lower than that of the controls (p < 0.02). In the patients with a history of stroke-like episodes (n = 10), both mean d-ROMs and BAP levels were increased compared with those of the controls (both p < 0.01). The mean BAP level of the patients without a history of stroke-like episodes (n = 4) was significantly decreased compared with that of the controls (p < 0.001), but the mean d-ROMs levels were not significantly different. Conclusion: d-ROMs and BAP tests indicated that patients carrying A3243G are always exposed to underlying oxidative stress, even at a remission state of stroke-like episodes.

A CROSS-OVER COMPARISON OF ANTI-ALBUMINURIC EFFECTS AMONG 4 TYPES CALCIUM CHANNEL BLOCKERS ON CHRONIC KIDNEY DISEASE: PP.33.310

Background and Objectives: At the intervention for hypertension with chronic kidney disease (CKD), albuminuria is one of the pivotal targets as well as strict blood pressure (BP) control for organ protection. Calcium channel blocker (CCB) is one of the most expected agents for CKD. Currently CCBs have been classified by half-life, drug delivery system and channel types. We tested anti-albuminuric effect and humoral factors level of 4 types of CCBs in CKD. Methods: Subjects were 50 hypertensives with CKD (male/female 22/28, age 69.8±10.8yrs, SBP/DBP 164.7±17.1/92.3±12.2 mmHg, s-Cr 0.81±0.37 mg/dl, urinary albumin excretion (UAE) 69.4 (33.5–142.6) mg/gCr). CCBs were administered for 12 weeks in a crossover manner. Tested agents were nifedipine CR, a long biological half-life L type CCB with controlled release system, cilnidipine, an N/L type CCB, efonidipine, a T/L type CCB and amlodipine, a long biological half-life L type CCB with trans-membrane approach. Results: Comparable BP reductions were obtained. UAE at endpoints ware as follow (mg/gCr, *P < 0.05): nifedipine CR 30.8 (17.3–81.1),* cilnidipine 33.9 (18.0–67.7),* efonidipine 51.0 (21.2–129.8), amlodipine 40.6 (18.7–94.7). By all agents, significant augmentations were observed in PRA, angiotensin I and angiotensin II (AngII). AngII at cilnidipine was significantly lower than that at amlodipine. PAC at cilnidipine and efonidipine was significantly lower than that at amlodipine. Nifedipine CR significantly reduced ANP concentration. Conclusions: It is revealed for the first time that, although all tested drugs reduced UAE, only nifedipine CR and cilnidipine could reach statistical difference. Thus, it is suggested that, in respect of albuminuria reduction, the 2 CCBs might be favorable for organ protection in CKD.

Levels of serum deoxyribonuclease I activity on admission in patients with acute myocardial infarction can be useful in predicting left ventricular enlargement due to remodeling

OBJECTIVES Serum deoxyribonuclease I (DNase I) activity has recently been highlighted as a potential diagnostic marker for the early detection of an acute myocardial infarction (AMI). We evaluated whether the serum DNase I activity was associated with the parameters of the left ventricular (LV) remodeling after an AMI. METHODS We measured the serum DNase I activity in 45 patients with an AMI who were admitted to our hospital within approximately 4 h of the onset of their chest pain. We also evaluated the LV ejection fraction (LVEF), LV end-diastolic volume (LVEDV), and LV end-systolic volume (LVESV) of each patient by echocardiography at the time of admission and at 6 months after the onset of the AMI. RESULTS The serum DNase I activity peaked at 3.5+/-2.0 h after the onset of the symptoms in the patients with an AMI, thereafter exhibiting a time-dependent decline within 12 h, and a return to the basal level within 24 h in almost all cases. Neither the LVEF, LVEDV, nor LVESV in each patient on admission exhibited a significant correlation to the peak levels of the serum DNase I activity. Although there was no correlation between the peak DNase I activity and LVEF at 6 months after the onset, a significant positive correlation of the peak DNase I activity with LVEDV and LVESV (r=0.48, p<0.001 and r=0.34, p=0.02, respectively) was found. Furthermore, the LVEDV at 6 months after the onset in the high DNase I activity group (> 17.9 U/L) were significantly higher than those in the low DNase I activity group (< or = 17.9 U/L) (118.0+/-28.2 ml vs 89.3+/-25.4 ml, p=0.026). CONCLUSIONS The serum DNase I activity level may predict LV enlargement associated with remodeling after an AMI.