Tomofumi Takaya

A Specific Role for eNOS-Derived Reactive Oxygen Species in Atherosclerosis Progression

Objective—When the availability of tetrahydrobiopterin (BH4) is deficient, endothelial nitric oxide synthase (eNOS) produces superoxide rather than NO (uncoupled eNOS). We have shown that the atherosclerotic lesion size was augmented in apolipoprotein E–deficient (ApoE-KO) mice overexpressing eNOS because of the enhanced superoxide production. In this study, we addressed the specific importance of uncoupled eNOS in atherosclerosis, and the potential mechanistic role for specific versus nonspecific antioxidant strategies in restoring eNOS coupling. Methods and Results—We crossed mice overexpressing eNOS in the endothelium (eNOS-Tg) with mice overexpressing GTP-cyclohydrolase I (GCH), the rate-limiting enzyme in BH4 synthesis, to generate ApoE-KO/eNOS-Tg/GCH-Tg mice. As a comparison, ApoE-KO/eNOS-Tg mice were treated with vitamin C. Atherosclerotic lesion formation was increased in ApoE-KO/eNOS-Tg mice compared with ApoE-KO mice. GCH overexpression in ApoE-KO/eNOS-Tg/GCH-Tg mice increased vascular BH4 levels and reduced plaque area. This reduction was associated with decreased superoxide production from uncoupled eNOS. Vitamin C treatment failed to reduce atherosclerotic lesion size in ApoE-KO/eNOS-Tg mice, despite reducing overall vascular superoxide production. Conclusion—In contrast to vitamin C treatment, augmenting BH4 levels in the endothelium by GCH overexpression reduced the accelerated atherosclerotic lesion formation in ApoE-KO/eNOS-Tg mice, associated with a reduction of superoxide production from uncoupled eNOS.

Local Overexpression of Toll-Like Receptors at the Vessel Wall Induces Atherosclerotic Lesion Formation Synergism of TLR2 and TLR4

Objective—Atherosclerosis is now considered as a chronic inflammatory disease, and inflammation is closely related to immune systems, which consist of innate-immunity and adaptive-immunity. Recently, toll-like receptors (TLRs) have been identified as key components of innate-immunity. We examined the role of local expressions of TLRs at the vessel wall in atherosclerosis. Methods and Results—We transfected cDNA encoding human TLR2 and TLR4 into the carotid arterial vessel wall of rabbits fed high-cholesterol diets with the use of HVJ-liposome. The rabbits were transfected with (1) pCMV-&bgr;-gal, (2) empty vector, (3) TLR2, (4) TLR4, (5) TLR2+4. X-gal staining and immunohistochemical analysis showed that the transfected plasmids were mainly expressed in the media. Neither TLR2 nor TLR4 transfection induced significant augmentation of atherosclerosis. Transfection of TLR2- and TLR4-containing HVJ synergistically accelerated atherosclerosis and increased expressions of vascular cell adhesion molecule 1, intercellular adhesion molecule 1, and MCP-1. Moreover, transfection of TLR2 and TLR4 resulted in synergistic activation of NF-&kgr;B at the vessel wall in vivo, and in vascular smooth muscle cells in vitro. Conclusions—Expressions of both TLR2 and TLR4 at the vessel wall synergistically accelerated atherosclerosis. The present study revealed the role of TLRs expressed locally at the vessel wall in the early stage of atherosclerosis.

Augmentation of Vascular Remodeling by Uncoupled Endothelial Nitric Oxide Synthase in a Mouse Model of Diabetes Mellitus

Objective—Diabetes mellitus is associated with increased oxidative stress, which induces oxidation of tetrahydrobiopterin (BH4) in vessel wall. Without enough BH4, eNOS is uncoupled to L-arginine and produces superoxide rather than NO. We examined the role of uncoupled eNOS in vascular remodeling in diabetes. Methods and Results—Diabetes mellitus was produced by streptozotocin in C57BL/6J mice. Under stable hyperglycemia, the common carotid artery was ligated, and neointimal formation was examined 4 weeks later. In diabetic mice, the neointimal area was dramatically augmented. This augmentation was associated with increased aortic superoxide formation, reduced aortic BH4/dihydrobiopterin (BH2) ratio, and decreased plasma nitrite and nitrate (NOx) levels compared with nondiabetic mice. Chronic BH4 treatment (10 mg/kg/d) reduced the neointimal area in association with suppressed superoxide production and inflammatory changes in vessels. BH4/BH2 ratio in vessel wall was preserved, and plasma NOx levels increased. Furthermore, in the presence of diabetes, overexpression of bovine eNOS resulted in augmentation of neointimal area, accompanied by increased superoxide production in the endothelium. Conclusions—In diabetes, increased oxidative stress by uncoupled NOSs, particularly eNOS, causes augmentation of vascular remodeling. These findings indicate restoration of eNOS coupling has an atheroprotective benefit in diabetes.

Torsades de Pointes with QT prolongation related to donepezil use.

An 83-year-old female, who had a history of anterior myocardial infarction, was treated for Alzheimers disease with donepezil. She suffered from repeated diarrhea and vomiting, and experienced syncope. She was admitted to our hospital and was diagnosed with acute colitis and syncope. On admission, her heart rate was 54 beats/min with regular rhythm. Laboratory data showed a low plasma potassium level. Electrocardiogram (ECG) showed poor R progression, ST elevation, negative T in precordial leads, and marked QT prolongation. Transthoracic echocardiogram showed the enlargement of the left atrium and aneurysmal area at the apex. Torsades de Pointes (TdP) with syncope and convulsion were confirmed on ECG monitoring twice after admission. We treated her with potassium chloride and started magnesium sulfate and lidocaine, and then added isoprenaline injection. After these treatments, her heart rate increased and we did not detect TdP again. With the aging population in Japan, prescriptions for donepezil are increasing. We have to be vigilant for syncope in patients taking donepezil, which is possibly related to QT prolongation and TdP.

Effect of Daily Glucose Fluctuation on Coronary Plaque Vulnerability in Patients Pre-Treated With Lipid-Lowering Therapy: A Prospective Observational Study

OBJECTIVES This study sought to investigate the effect of daily glucose fluctuation on coronary plaque properties in patients with coronary artery disease (CAD) pre-treated with lipid-lowering therapy. BACKGROUND There is growing evidence that glucose fluctuation, as a residual risk apart from dyslipidemia, is an important factor contributing to the development of CAD. METHODS This prospective study enrolled 70 consecutive CAD patients who were referred for percutaneous coronary intervention and whose low-density lipoprotein cholesterol level was <120 mg/dl under statin treatment or <100 mg/dl without statins. Daily glucose fluctuation was analyzed by measuring the mean amplitude of glycemic excursion (MAGE). The plaque properties in the culprit and nonculprit lesions were assessed by virtual histology intravascular ultrasound, and the volume percentage of necrotic core within the plaque (%NC) and the presence of thin-cap fibroatheroma were evaluated. RESULTS In total, 165 lesions were evaluated in 70 patients (40 diabetic and 30 nondiabetic patients). %NC was well correlated with MAGE (r = 0.490, p <0.001). A linear mixed effect model showed that MAGE had the strongest effect on %NC (coefficient β = 0.080 ± 0.020 [standard error], p < 0.001). The generalized linear mixed effect model revealed that MAGE was the only independent predictor of the presence of thin-cap fibroatheroma (odds ratio: 1.037; 95% confidence interval: 1.010 to 1.065; p = 0.007). CONCLUSIONS Daily glucose fluctuation may have an effect on coronary plaque vulnerability in patients with CAD pre-treated with lipid-lowering therapy. Further investigations should address the rationale for the early detection and control of glucose fluctuation in the era of universal statin use for CAD patients.

The impact of in-stent neoatherosclerosis on long-term clinical outcomes: an observational study from the Kobe University Hospital optical coherence tomography registry

AIMS Although pathological studies have indicated the development of neoatherosclerosis (NA) after stenting, its risk factors and impact on future clinical events remain unclear. We aimed to clarify the possible risk factors for NA development and to evaluate the impact of NA in a large Japanese observational OCT database of patients with coronary heart disease. METHODS AND RESULTS One hundred and seventy-five consecutive patients (314 lesions) who underwent OCT examination >1 year after bare metal or drug-eluting stent implantation were enrolled. We assessed the presence of NA by follow-up OCT and compared adverse clinical events between NA+ and NA- patients. Forty-six patients had NA at the follow-up OCT. These patients had higher low-density lipoprotein (LDL) cholesterol and C-reactive protein (CRP) levels at follow-up. In multivariate logistic analysis, LDL cholesterol and CRP levels at follow-up were independently associated with the presence of NA (odds ratio [OR]: 1.022, p=0.008, OR 1.022, p=0.001, respectively). Moreover, patients with NA had a higher incidence of major adverse cardiac events (MACE) at follow-up. Multivariate Cox hazard analysis showed that the presence of NA was an independent risk factor for MACE (hazard ratio: 2.909, p=0.012). CONCLUSIONS High LDL cholesterol and CRP levels may be risk factors for NA development in patients treated with coronary stents. Moreover, the presence of NA was independently associated with MACE, suggesting the need for careful clinical follow-up of these patients.

Serial Optical Coherence Tomography Evaluation at 6, 12, and 24 Months After Biolimus A9-Eluting Biodegradable Polymer-Coated Stent Implantation

BACKGROUND The Nobori (Terumo Corporation, Tokyo, Japan) is a biolimus A9-eluting stent (BES) featured with a biodegradable polymer coated on the abluminal side only. We previously reported that favourable vessel healing was achieved at 6-12 months after BES implantation. However, detailed long-term vessel reaction after BES deployment is unclear. METHODS Twenty-two BESs were serially evaluated using optical coherence tomography (OCT) at 6, 12, and 24 months after stenting. Average neointimal thickness, uncovered struts, and neointimal unevenness score (each cross-section as maximum neointimal thickness in 1 cross section divided by the average neointimal thickness of the same cross-section) were manually measured. In addition, we evaluated the percentage of struts with peri-strut low-intensity area (a region around stent struts that homogenously showed less intensity than the surrounding tissue, which suggests fibrin deposition or impaired neointima maturation), thrombi, and atherogenic neointimas (neointimas containing a diffuse border and poor-signal region with invisible struts due to marked signal attenuation). RESULTS Serial OCT observation revealed a small gradual increase in neointimal thickness from 6 to 24 months (73 ± 24 μm; 81 ± 26 μm; and 108 ± 35 μm, respectively, P = 0.001) with a nonsignificant decrease in the lumen area (6.36 ± 1.98 mm(2); 6.18 ± 2.04 mm(2); and 5.87 ± 2.06 mm(2); P = 0.72). Frequency of uncovered struts (3.89 ± 3.91%; 1.55 ± 1.63%; and 0.23 ± 0.67%; P = 0.001), neointimal unevenness score (1.95 ± 0.18% to 1.86 ± 0.19% to 1.78 ± 0.17; P = 0.012), percentage of thrombi (5%, 0%, and 0%; P = 0.37) and peri-strut low-intensity area (6.8%, 5.1%, and 1.6%; P = 0.017) decreased from 6 to 12 and 24 months. Atherogenic neointima was not observed in the event-free OCT cohort. CONCLUSIONS The Nobori stent achieved acceptable long-term vessel healing, mostly without adverse vessel reactions.

Clinical Structural Anatomy of the Inferior Pyramidal Space Reconstructed Within the Cardiac Contour Using Multidetector‐Row Computed Tomography

Although many studies have described the detailed anatomy of the inferior pyramidal space, it may not be easy for cardiologists who have few chances to study cadaveric hearts to understand the correct morphology of the structure. The inferior pyramidal space is the part of extracardiac fibro‐adipose tissue wedging between the 4 cardiac chambers from the diaphragmatic surface of the heart. Many cardiologists have interests in pericardial adipose tissue, but the inferior pyramidal space seems to have been neglected. A number of important structures, including the coronary sinus, atrioventricular node, atrioventricular nodal artery, membranous septum, muscular atrioventricular sandwich (previously called the “muscular atrioventricular septum”), atrial septum, ventricular septum, aortic valvar complex, mitral valvar attachment, and tricuspid valvar attachment are associated with the inferior pyramidal space. We previously revealed its 3‐dimensional live anatomy using multidetector‐row computed tomography. Moreover, the 3‐dimensional understanding of the anatomy in association with the cardiac contour is important from the viewpoints of clinical cardiac electrophysiology. The purpose of this article is to demonstrate extended findings regarding the clinical structural anatomy of the inferior pyramidal space, which was reconstructed in combination with the cardiac contour using multidetector‐row computed tomography, and discuss the clinical implications of the findings.

Optimal angulations for obtaining an en face view of each coronary aortic sinus and the interventricular septum: Correlative anatomy around the left ventricular outflow tract

An optimal image intensifier angulation used for obtaining an en face view of a target structure is important in electrophysiologic procedures performed around each coronary aortic sinus (CAS). However, few studies have revealed the fluoroscopic anatomy of the target area. This study investigated the optimal angulation for each CAS and the interventricular septum (IVS). The study included 102 consecutive patients who underwent computed tomography coronary angiography. The optimal angle for each CAS was determined by rotating the volume‐rendered image around the vertical axis. The angle formed between the anteroposterior axis and IVS was measured using the horizontal section. The frontal direction was defined as zero, positive, or negative if the en face view of the target CAS was obtained in the frontal view, left anterior oblique (LAO) direction, or right anterior oblique (RAO) direction, respectively. The optimal angles for the left, right, and non‐CASs were 120.3 ± 10.5°, 4.8 ± 16.3°, and −110.0 ± 13.8°, respectively. The IVS angle was 42.6 ± 8.5°. Accordingly, the optimal image intensifier angulations for the left, right, and non‐CASs and the IVS were estimated to be RAO 60°, LAO 5°, LAO 70°, and RAO 50°, respectively. The IVS angle was the most common independent predictor of the optimal angle for each CAS. Differences in the optimal angulations for each CAS and the IVS are demonstrated. The biplane angulation needs to be tailored according to the individual patients and target structures for electrophysiologic procedures. Clin. Anat. 28:494–505, 2015.

Early Phase Arterial Reaction Following Drug-Eluting and Bare-Metal Stent Implantation in Patients With ST-Segment Elevation Myocardial Infarction.

The early phase arterial reaction after implantation of second-generation drug-eluting stents (2nd DES) and baremetal stents (BMS) in patients with ST-segment elevation myocardial infarction (STEMI) remains unclear.The MECHANISM pilot study is a multi-center prospective registry that enrolled 24 STEMI patients (from 11 centers) who had undergone implantation of everolimus-eluting (n = 6), biolimus A9-eluting (n = 6) or zotarolimus-eluting stents (n = 6), or BMS (n = 6). Scheduled optical coherence tomography (OCT) was performed 2 weeks after implantation, and images were independently analyzed at a core laboratory in a blinded fashion. Intra-stent thrombus was quantitatively analyzed in terms of the maximal area and the percentage of cross-sections with thrombus (the numbers of cross-section with thrombus × 100 divided by total number of cross-sections within the stented segment). More than 90% of struts were already covered 2 weeks after the index procedure, regardless of the stent type. There were no differences in stent diameter, minimal lumen diameter, minimal lumen area, neointimal thickness, or the frequencies of malapposed and uncovered struts among the 4 groups. The quantity of intra-stent thrombus also did not differ among the 4 groups.The results of this pilot study suggest that the 2-week vascular responses seem to be similar among 2nd DES and BMS in STEMI patients. Considering the possible advantage of 2nd DES in the prevention of restenosis, 2nd DES are a feasible option for the treatment of patients with STEMI.