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Featured researches published by Ryo Kameda.


Cardiovascular Diabetology | 2012

Postprandial hyperglycemia and endothelial function in type 2 diabetes: focus on mitiglinide

Lisa Kitasato; Taiki Tojo; Yuko Hatakeyama; Ryo Kameda; Takehiro Hashikata; Minako Yamaoka-Tojo

The risk of cardiovascular complication in a diabetes patient is similar to that in a nondiabetic patient with a history of myocardial infarction. Although intensive control of glycemia achieved by conventional antidiabetic agents decreases microvascular complications such as retinopathy and nephropathy, no marked effect has been reported on macrovascular complications or all-cause mortality. Evidence from VADT, ACCORD, and ADVANCE would suggest that glycemic control has little effect on macrovascular outcomes. Moreover, in the case of ACCORD, intensive glycemic control may be associated with an increased risk of mortality. There is sufficient evidence that suggests that postprandial hyperglycemia may be an independent risk factor for cardiovascular disease in diabetes patients. However, there are no prospective clinical trials supporting the recommendation that lowering postprandial blood glucose leads to lower risk of cardiovascular outcomes. Mitiglinide is a short-acting insulinotropic agent used in type 2 diabetes treatment. It has a rapid stimulatory effect on insulin secretion and reduces postprandial plasma glucose level in patients with type 2 diabetes. Because of its short action time, it is unlikely to exert adverse effects related to hypoglycemia early in the morning and between meals. Mitiglinide reduces excess oxidative stress and inflammation, plays a cardioprotective role, and improves postprandial metabolic disorders. Moreover, mitiglinide add-on therapy with pioglitazone favorably affects the vascular endothelial function in type 2 diabetes patients. These data suggest that mitiglinide plays a potentially beneficial role in the improvement of postprandial hyperglycemia in type 2 diabetes patients and can be used to prevent cardiovascular diseases. Although the results of long-term, randomized, placebo-controlled trials for determining the cardiovascular effects of mitiglinide on clinical outcomes are awaited, this review is aimed at summarizing substantial insights into this topic.


Nutrition & Metabolism | 2011

Circulating interleukin-18: A specific biomarker for atherosclerosis-prone patients with metabolic syndrome

Minako Yamaoka-Tojo; Taiki Tojo; Kazuki Wakaume; Ryo Kameda; Shinji Nemoto; Naonobu Takahira; Takashi Masuda; Tohru Izumi

BackgroundMetabolic syndrome (MetS) is associated with an increased risk of the development of atherosclerotic cardiovascular disease (CVD). Interleukin-18 (IL-18), which is a pleiotropic proinflammatory cytokine with important regulatory functions in the innate immune response system, plays a crucial role in vascular pathologies. IL-18 is also a predictor of cardiovascular death in patients with CVD and is involved in atherosclerotic plaque destabilization.ResultsIn order to determine if circulating levels of IL-18 can serve as a specific biomarker for distinguishing MetS patients from pre-MetS subjects, we studied 78 patients with visceral fat deposition and 14 age-matched control subjects. Increased levels of IL-18 were observed more frequently in patients with MetS than in pre-MetS subjects and were positively associated with waist circumference. Serum levels of IL-18 were significantly reduced by a change in weight caused by lifestyle modifications. There was a significant interaction between waist circumference and serum IL-18 concentration. Weight loss of at least 5% of the body weight caused by lifestyle modification decreased IL-18 circulating levels relative to the reduction in waist circumference and blood pressure, suggesting that this degree of weight loss benefits the cardiovascular system.ConclusionIL-18 may be a useful biomarker of the clinical manifestations of MetS and for the management of the risk factors of CVD.


Catheterization and Cardiovascular Interventions | 2013

Two-week interval optical coherence tomography: imaging evidence on neointimal coverage completion after implantation of the Endeavor zotarolimus-eluting stent.

Makoto Nishinari; Takao Shimohama; Taiki Tojo; Takaaki Shiono; Hisahito Shinagawa; Ryo Kameda; Naoyoshi Aoyama; Tohru Izumi

To obtain imaging evidence by 2‐week optical coherence tomography (OCT) on the completion of neointimal coverage (NIC; the percentage of stent strut coverage and thickness of the formed neointima) completion after implantation of the Endeavor zotarolimus‐eluting stent (E‐ZES).


International Heart Journal | 2015

Rivaroxaban Inhibits Angiotensin II-Induced Activation in Cultured Mouse Cardiac Fibroblasts Through the Modulation of NF-κB Pathway

Takehiro Hashikata; Minako Yamaoka-Tojo; Sayaka Namba; Lisa Kitasato; Ryo Kameda; Masami Murakami; Hiroe Niwano; Takao Shimohama; Taiki Tojo; Junya Ako

Cell migration, proliferation, and differentiation of cardiac fibroblasts (CFs) play a central role in cardiac fibrosis. Factor Xa (FXa)-dependent protease-activated receptor (PAR)-1 and PAR-2 have been reported as important targets in proinflammatory and fibroproliferative diseases. From this viewpoint, we aimed to investigate whether treatment of rivaroxaban, an approved oral direct FXa inhibitor, attenuates functional changes in angiotensin (Ang) II-induced mouse CFs.Confluent cultured mouse CFs were pretreated with or without rivaroxaban. Ang II-induced cell migration was decreased by 73% in rivaroxaban induced cells. Rivaroxaban inhibited Ang II-induced cell proliferation by 27% at 0.01 μg/ mL, 69% at 0.1 μg/mL, 71% at 1 μg/mL, and 69% at 5 μg/mL. In mouse cytokine array measuring 40 cytokines, the productions of interleukin-16, TIMP-1, and tumor necrosis factor-α (TNF-α) were significantly reduced with 0.1 μg/mL of rivaroxaban pretreatment (all P < 0.05). TIMP-1 levels in the culture supernatant measured by ELISA were also decreased by rivaroxaban pretreatment in Ang II-induced CFs (35% decrease at 0.01 μg/mL, 47% at 0.1 μg/mL, 47% at 1 μg/mL, and 57% at 5 μg/mL). In the dual reporter assay analysis, rivaroxaban inhibited various inflammatory signal pathways, including the nuclear factor-kappa B (NF-κB), active protein-1 (AP-1), and mitogen-activated protein kinase (MAPK) pathways (decreases of 82%, 78%, and 75%, respectively).These data suggest that rivaroxaban inhibits Ang II-induced functional activation in cultured mouse CFs via inhibiting NF-κB and MAPK/AP-1 signaling pathways, which may be a possible target of heart failure, through the antifibrotic and anti-inflammatory efficacy of rivaroxaban in Ang II-stimulated cardiac fibroblasts.


Biomedicine & Pharmacotherapy | 2015

Clinical outcomes of chronic kidney disease patients treated with everolimus-eluting stents (EES) and paclitaxel-eluting stents (PES).

Lisa Kitasato; Takao Shimohama; Yuki Ikeda; Sayaka Namba; Takehiro Hashikata; Ryo Kameda; Nobuhiro Sato; Ichiro Takeuchi; Minako Yamaoka-Tojo; Taiki Tojo; Junya Ako

BACKGROUND The target lesion revascularization of paclitaxel-eluting stents (PES) has been reported to be lower than that of sirolimus-eluting stents in patients on hemodialysis (HD). However, the comparison of PES and second generation drug-eluting stents in CKD patients has not been fully investigated. We compared clinical outcomes of everolimus-eluting stents (EES) and PES in CKD patients. METHODS Hundred and forty seven CKD patients (eGFR<60mLmin(-1)1.73m(-2)) treated with PES (n=74, from May 2007 to December 2009) and EES (n=73, from January 2010 to January 2013) were enrolled in the study. Major adverse cardiac events (MACEs) were defined as death, non-fatal myocardial infarction, and ischemia driven target lesion revascularization. RESULTS The incidence of 36-month MACE was significantly lower in EES, non-HD group compared to PES, non HD group (0% in EES group and 13.5% in PES group, respectively, P<0.01). There was no significant difference in MACE between EES and PES in HD patients (5.4% in PES group and 5.5% in EES group, P=0.98). In multivariate analysis, PES group and PES ISR were independent factors for worse incidence of MACE. CONCLUSIONS In CKD patients, PES was associated with worse clinical outcomes in non-HD patients as compared with EES.


Journal of the American College of Cardiology | 2018

BIORESORBABLE SCAFFOLD FOR TREATMENT OF CORONARY ARTERY LESIONS: FINAL INTRAVASCULAR ULTRASOUND RESULTS FROM THE ABSORB JAPAN TRIAL

Kozo Okada; Yasuhiro Honda; Hideki Kitahara; Masayasu Ikutomi; Ryo Kameda; M. Brooke Hollak; Paul G. Yock; Hajime Kusano; Wai-Fung Cheong; Sudhir K; Peter J. Fitzgerald; Takeshi Kimura

Scaffold under-expansion is associated with late adverse outcomes after polymeric scaffold (BVS) implantation, while underlying mechanism of this association remains unknown. The IVUS cohort of ABSORB JAPAN trial was designed to characterize detailed device performance and long-term vessel response


Journal of Atherosclerosis and Thrombosis | 2017

Lower Level of Low Density Lipoprotein Cholesterol is Associated with a Higher Increase in the Fractional Flow Reserve in Patients with Fixed-dose Rosuvastatin

Takehiro Hashikata; Taiki Tojo; Yusuke Muramatsu; Toshimitsu Sato; Ryota Kakizaki; Teruyoshi Nemoto; Kazuhiro Fujiyoshi; Sayaka Namba; Lisa Kitasato; Takuya Hashimoto; Ryo Kameda; Takao Shimohama; Minako Yamaoka-Tojo; Junya Ako

Aim: Fractional flow reserve (FFR) reflects on the diffuse atherosclerosis per coronary artery. It is unknown whether the statin therapy affects long term FFR after stenting. The aim of this study was to evaluate the long term FFR after stent implantation in patients who are intaking fixed-dose rosuvastatin. Methods: A total of 22 patients with stable angina pectoris were enrolled. The values of FFR were measured before, immediately after, and 18 months after (follow-up day) the implantation of everolimus eluting stent (EES; Promus Element™ or Promus Element Plus™). A fixed dose of rosuvastatin at 5 mg/day was administrated to all patients. Results: Of the 22 patients, 2 were excluded because of adverse effect of rosuvastatin and in-stent total occlusion after EES implantation. Overall, the values of FFR immediately after and 18 months after EES implantation did not show significant change (from 0.90 ± 0.05 to 0.88 ± 0.06, p = 0.16). However, there was a significant negative correlation between low density lipoprotein (LDL) cholesterol level at follow-up day and changes in the value of FFR (p = 0.01, r = −0.74). There was an increase in the FFR value after stenting in 8 out of 9 patients with LDL cholesterol level below 75 mg/dl (area under the curve 0.92, p = 0.0005). Conclusions: LDL cholesterol level was associated with the change in the FFR value in patients following stent implantation. Lower LDL cholesterol tended to improve in the long-term FFR, underscoring the importance of lowering LDL cholesterol to prevent the progression of coronary atherosclerosis.


Heart and Vessels | 2016

Teneligliptin improves left ventricular diastolic function and endothelial function in patients with diabetes

Takehiro Hashikata; Minako Yamaoka-Tojo; Ryota Kakizaki; Teruyoshi Nemoto; Kazuhiro Fujiyoshi; Sayaka Namba; Lisa Kitasato; Takuya Hashimoto; Ryo Kameda; Emi Maekawa; Takao Shimohama; Taiki Tojo; Junya Ako


International Heart Journal | 2014

Factor Xa in Mouse Fibroblasts May Induce Fibrosis More Than Thrombin

Lisa Kitasato; Minako Yamaoka-Tojo; Takehiro Hashikata; Sayaka Ishii; Ryo Kameda; Takao Shimohama; Taiki Tojo; Junya Ako


Heart and Vessels | 2016

Neointimal coverage of zotarolimus-eluting stent at 1, 2, and 3 months’ follow-up: an optical coherence tomography study

Takehiro Hashikata; Taiki Tojo; Sayaka Namba; Lisa Kitasato; Takuya Hashimoto; Ryo Kameda; Takao Shimohama; Minako Yamaoka-Tojo; Junya Ako

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