Eisaku Nakamura

Publications (10)11.59 Total impact

• Article: Insulin induces internalization of the plasma membrane 5-hydroxytryptamine2A (5-HT2A) receptor in the isolated human endothelium-denuded saphenous vein via the phosphatidylinositol 3-kinase pathway.

  Tasuku Kanai, Masachika Kuwabara, Naoko Tanaka-Totoribe, Eisaku Nakamura, Yasuko Matsuo, Shuji Gamoh, Akito Suzuki, Yujiro Asada, Hiroaki Hisa, Ryuichi Yamamoto
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  ABSTRACT: The aim of this study was to investigate the relaxant effect of insulin on the 5-hydroxytryptamine (5-HT)-induced constriction of the human endothelium-denuded saphenous vein (SV) and its signal transduction pathway. During the 5-HT-induced sustained constriction of vessels, insulin induced vasorelaxation in a concentration-dependent manner. This insulin-induced vasorelaxation was partially attenuated by L-NAME, a nitric oxide synthase (NOS) inhibitor, and was abolished by wortmannin, a phosphatidylinositol 3-kinase (PI3-K) inhibitor. Insulin increased the Ser(473) phosphorylation of Akt. Endothelial NOS and inducible NOS protein expressions were observed in SV smooth muscle when insulin induced relaxation of SV vessels preconstricted with 5-HT. Although insulin did not affect the total protein level of 5-HT(2A) receptors, it decreased the particulate protein level and reciprocally increased the soluble protein level of 5-HT(2A) receptors in a concentration-dependent manner. These results demonstrate that insulin can induce the internalization of 5-HT(2A) receptors from the plasma membrane to the cytoplasm. The insulin-induced internalization of 5-HT(2A) receptors was abolished by wortmannin but was not affected by L-NAME. These results suggest that the relaxant effect of insulin on 5-HT-induced vasoconstriction is mediated in part by the internalization of plasma membrane 5-HT(2A) receptors and the production of nitric oxide via the PI3-K/Akt pathway.
  Journal of Pharmacological Sciences 02/2012; 118(2):178-85. · 2.08 Impact Factor
• Article: The defective protein level of myosin light chain phosphatase (MLCP) in the isolated saphenous vein, as a vascular conduit in coronary artery bypass grafting (CABG), harvested from patients with diabetes mellitus (DM).

  Yasuko Matsuo, Masachika Kuwabara, Naoko Tanaka-Totoribe, Tasuku Kanai, Eisaku Nakamura, Shuji Gamoh, Akito Suzuki, Yujiro Asada, Hiroaki Hisa, Ryuichi Yamamoto
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  ABSTRACT: We examined the contractile reactivity to 5-hydroxytryptamine (5-HT) in isolated human saphenous vein (SV), as a vascular conduit in coronary artery bypass grafting (CABG), harvested from patients with diabetes mellitus (DM) and non-DM (NDM). Vascular rings of endothelium-denuded SV were used for functional and biochemical experiments. The vasoconstrictions caused by 5-HT were significantly greater (hyperreactivity) in the DM group than in the NDM group. RhoA/ROCK pathway is activated by various G-protein-coupled receptor agonists and consequently induces phosphorylation of myosin phosphatase target subunit 1 (MYPT1), a subunit of myosin light chain phosphatase (MLCP), which inhibits MLCP activity. In the resting state of the vessels, total tissue protein levels of 5-HT(2A) receptor, 5-HT(1B) receptor, RhoA, ROCK1, and ROCK2 did not differ between NDM and DM groups. However, the total protein level of MYPT1 was significantly lower in the DM group than in the NDM group. Furthermore, the ratio of P(Thr(696))-MYPT1 to total MYPT1 was significantly higher in the DM group than in the NDM group. These results suggest that the hyperreactivity to 5-HT in the SV smooth muscle of patients with DM is due to not only enhanced phosphorylation of MLCP but also defective protein level of MLCP. Thus, we reveal for the first time that the defective protein level of MLCP in the DM group can partially explain the poor patency of SV graft harvested from patients with DM.
  Biochemical and Biophysical Research Communications 07/2011; 412(2):323-7. · 2.48 Impact Factor
• Source

  Available from: Mitsuhiro Yano

  Article: Factors influencing permanent neurologic dysfunction and mortality after total arch replacement with separate arch vessel grafting using selective cerebral perfusion.

  Kunihide Nakamura, Eisaku Nakamura, Mitsuhiro Yano, Katsuhiko Niina, Kazushi Kojima, Toshio Onitsuka
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  ABSTRACT: The present study was undertaken to identify risk factors for permanent neurological dysfunction (PND) and in-hospital mortality after total aortic arch replacement (TAR) with separate arch vessel grafting using selective cerebral perfusion (SCP) and hypothermic circulatory arrest. Between 1998 and 2008, we preformed a TAR on 143 consecutive patients in two centers by identical methods. Of these, 19 (13.3%) were emergency operations, and 46 (32.2%) were open stent-graft placements. Statistical analysis was performed to determine risk factors for PND and mortality, and furthermore, the survival rate was analyzed. The in-hospital mortality rate was 4.9%, with chronic renal failure (p = 0.0013, odds ratio 10.0) as a significant risk factor. Nine patients (6.3%) had PND, with significant risk factors identified as (1) the presence of an old cerebral or silent lacunar infarction on preoperative imaging methods (p = 0.0458, odds ratio 8.0) and (2) duration of SCP (p = 0.0026, odds ratio 1.036). Long-term survival was the same in patients with or without PND. The enhanced vulnerability of the brain in patients with a pre-existing old cerebral infarction or silent lacunar infarction is reflected by a high incidence of PND. Chronic renal failure had an impact on in-hospital mortality.
  Annals of thoracic and cardiovascular surgery : official journal of the Association of Thoracic and Cardiovascular Surgeons of Asia. 02/2011; 17(1):39-44.
• Article: Relative contributions of 5-hydroxytryptamine (5-HT) receptor subtypes in 5-HT-induced vasoconstriction of the distended human saphenous vein as a coronary artery bypass graft.

  Eisaku Nakamura, Naoko Tanaka, Masachika Kuwabara, Atsushi Yamashita, Yasuko Matsuo, Tasuku Kanai, Toshio Onitsuka, Yujiro Asada, Hiroaki Hisa, Ryuichi Yamamoto
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  ABSTRACT: It is established that the segment of saphenous vein (SV) that is widely used as a conduit vessel in coronary artery bypass graft (CABG) surgery is distended with high pressure to check for leaks and to increase the patency before implantation into coronary arterial circulation. The aim of the present study was to elucidate the relative contributions of 5-hydroxytryptamine (5-HT) receptor subtypes responsible for 5-HT-induced vasoconstriction of the distended human SV. Whereas about half of the 5-HT-induced vasoconstriction still remained in the presence of supramaximum concentration of sarpogrelate or of SB224289 (5-HT(2A) and 5-HT(1B) receptor antagonists, respectively), simultaneous treatment with sarpogrelate and SB224289 almost completely inhibited the 5-HT-induced vasoconstriction. Immunopositive staining for 5-HT(2A) and 5-HT(1B) receptors was detected in smooth muscle cells of the distended human SV and there was no significant difference between the immunopositive areas of 5-HT(2A) and 5-HT(1B) receptors. These results demonstrate that 5-HT(2A) and 5-HT(1B) receptors similarly contribute to 5-HT-induced vasoconstriction in human distended SV. Thus, when the SV is used as a CABG conduit, a combination of 5-HT(2A) and 5-HT(1B) receptor antagonists would appear to be most useful to prevent 5-HT-induced spasm.
  Biological & Pharmaceutical Bulletin 01/2011; 34(1):82-6. · 1.66 Impact Factor
• Article: Outcome after valve surgery in octogenarians and efficacy of early mobilization with early cardiac rehabilitation.

  Kunihide Nakamura, Eisaku Nakamura, Katsuhiko Niina, Kazushi Kojima
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  ABSTRACT: This study aimed to compare postoperative complications and the surgical outcome in patients aged <80 years versus octogenarian patients. Another aim was to evaluate the safety and efficacy of early mobilization with early cardiac rehabilitation in octogenarians. A retrospective analysis was performed in 138 consecutive patients (group Y comprised 118 patients <80 years, and group O comprised 20 octogenarians) who had undergone valve surgery at the authors' institution between July 2007 and December 2009. Furthermore, the efficacy of early mobilization with early cardiac rehabilitation and long-term results were analyzed in 40 consecutive octogenarian patients undergoing valve surgery from 2000. The late survival follow-up was 100% complete. Redo cardiac operations were more frequent (O group 15.0% vs. Y group 3.4%, P = 0.011), and the preoperative EuroSCORE was significantly higher in group O than in group Y (group O 16.4 ± 18.3 vs. group Y 7.5 ± 9.1, P = 0.001). The incidence of delirium/confusion and worsening of renal function after surgery was higher in group O. The hospital mortality was 1.7% in group Y and no hospital death in group O (P > 0.99). Early mobilization with early cardiac rehabilitation significantly reduced the incidence of postoperative delirium/confusion and increased the number of patients who could return directly home. The actuarial 5-year survival rate was 77.7% for octogenarians. Although there were more high-risk patients among the octogenarians, valve surgery was a safe, low-risk procedure with excellent long-term results. Early mobilization with early cardiac rehabilitation was significantly effective and safe for postoperative recovery in octogenarians after cardiac valve surgery.
  General Thoracic and Cardiovascular Surgery 12/2010; 58(12):606-11.
• Source

  Available from: atcs.jp

  Article: Acute aortic regurgitation resulting from dehiscence of the aortic valve commissures.

  Eisaku Nakamura, Kunihide Nakamura, Katsuhiko Niina, Kojima Kazushi, Hirohito Ishii, Akira Ishihara Md, Hirohide Kubo, Imakiire Satoru
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  ABSTRACT: A 62-year-old man with a history of hypertension complained of cough and dyspnea and was admitted to a family doctor. He was transferred to our hospital for further investigation and therapy, a result of his doctor's suspicions of aortic regurgitation (AR) with infective endocarditis. During the operation, acute AR was found to be caused by dehiscence of the aortic valve commissures, and the valve was replaced with a mechanical valve. Postoperative course was uneventful. We reviewed reported cases of acute AR resulting from dehiscence of the aortic valve commissures.
  Annals of thoracic and cardiovascular surgery : official journal of the Association of Thoracic and Cardiovascular Surgeons of Asia. 08/2010; 16(4):294-6.
• Article: Spontaneous left subclavian artery dissection with concurrent thrombosis and embolic occlusion of the lower limbs: report of a case.

  Kunihide Nakamura, Eisaku Nakamura, Masakazu Matsuyama, Katsuhiko Niina, Hirohito Ishii
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  ABSTRACT: A subclavian artery dissection (SAD) is usually associated with coexisting aortic disease, and spontaneous SAD is extremely rare. This report presents the case of a spontaneous SAD patient who developed atypical clinical symptoms. A 41-year-old woman presented with bilateral ischemia of her lower limbs. An urgent bilateral femoral thrombo-embolectomy was performed using a balloon catheter. Postoperative enhanced computed tomography (CT) demonstrated a localized thrombus in the left subclavian artery extending toward the descending thoracic aorta, and a follow-up CT angiogram obtained 3 months later revealed left SAD and complete resolution of the thrombus. The patient was anticoagulated with warfarin in addition to antiplatelet drugs after the balloon catheter thromboembolectomy. This is the first report of lower limb ischemia caused by an embolism from a mural thrombus of the descending thoracic aorta extending from spontaneous SAD.
  Surgery Today 07/2010; 40(7):658-61. · 1.22 Impact Factor
• Article: Open surgery or stent repair for descending aortic diseases: Results and risk factor analysis.

  Kunihide Nakamura, Masakazu Matsuyama, Mitsuhiro Yano, Yoshikazu Yano, Hiroyuki Nagahama, Eisaku Nakamura, Toshio Onitsuka
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  ABSTRACT: Less invasive stent graft (SG) repair was compared with open surgery for patients with descending thoracic aortic diseases. Thirty six patients undergoing SG repair (SG group) were matched for age, sex, location and pathology of aortic disease with a 36-patient surgical cohort (OS group), and retrospective matched case-control study was performed with respect to outcomes and risk factors for adverse outcomes. Mortality rate was 5.6% in OS group and none in SG group (p=0.4930), and there was no significant difference in stroke and paraplegia rates between two groups. A higher prevalence of secondary procedures due to endoleak was seen in the patients of SG group (p=0.0113). Perioperative hypotension was an independent risk factor for in-hospital mortality (p=0.0071, odds ratio=34) and preoperative renal dysfunction was independent risk factor for paraplegia (p=0.0076, odds ratio=17.6). Although the importance of patient selection is emphasized to prevent endoleak, mortality rate was low in patients who underwent SG repair. SG repair is a promising alternative technique to open surgery for thoracic aortic diseases.
  Scandinavian cardiovascular journal: SCJ 11/2008; 43(3):201-7. · 1.07 Impact Factor
• Article: Both 5-hydroxytryptamine 5-HT2A and 5-HT1B receptors are involved in the vasoconstrictor response to 5-HT in the human isolated internal thoracic artery.

  Naoko Tanaka, Eisaku Nakamura, Masamichi Ohkura, Masachika Kuwabara, Atsushi Yamashita, Toshio Onitsuka, Yujiro Asada, Hiroaki Hisa, Ryuichi Yamamoto
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  ABSTRACT: 1. The 5-hydroxytryptamine (5-HT, serotonin) receptor subtypes that mediate vasoconstriction in the human internal thoracic artery (ITA), which is frequently used as an arterial graft, remain unclear. The aim of the present study was to elucidate the 5-HT receptor subtypes responsible for 5-HT-induced contraction of the human ITA. 2. The contractile responses to 5-HT of endothelium-denuded human ITA obtained from patients undergoing coronary bypass surgery were examined. In addition, we investigated the effects of sarpogrelate and SB224289, antagonists of 5-HT(2A) and 5-HT(1B) receptors, respectively, on the 5-HT-induced vasoconstriction. Finally, 5-HT(2A) and 5-HT(1B) receptors in the human ITA were immunolabelled. 3. 5-Hydroxytryptamine (1 nmol/L-10 micromol/L) caused vasoconstriction in a concentration-dependent manner. Both sarpogrelate (1 micromol/L) and SB224289 (1 micromol/L) significantly, but not completely, inhibited 5-HT-induced vasoconstriction. 4. Conversely, simultaneous pretreatment with supramaximum concentrations (1 micromol/L for both) of sarpogrelate and SB224289 almost completely inhibited the 5-HT-induced vasoconstriction. 5. Immunopositive staining for 5-HT(2A) and 5-HT(1B) receptors was detected in smooth muscle cells of the human ITA. 6. These results demonstrate that, in human ITA, 5-HT-induced vasoconstriction is mediated by activation of both 5-HT(2A) and 5-HT(1B) receptors. Thus, when the human ITA is used as an arterial graft, a combination of 5-HT(2A) and 5-HT(1B) receptor antagonists would appear to be most useful to prevent 5-HT-induced vasospasm.
  Clinical and Experimental Pharmacology and Physiology 08/2008; 35(7):836-40. · 1.85 Impact Factor
• Article: Protruding thrombus in the left atrium found 7 years after percutaneous transvenous mitral commissurotomy: report of a case.

  Kouji Furukawa, Masachika Kuwabara, Eisaku Nakamura, Hironori Ninomiya, Toshio Onitsuka
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  ABSTRACT: A 50-year-old man was transferred to our hospital for investigation of cerebellar infarction, thought to have been caused by cardiac thromboembolism. We assumed that the cardiac thromboembolism had occurred as a late complication of a percutaneous transvenous mitral commissurotomy (PTMC) performed 7 years earlier. An echocardiogram and thoracic computed tomography revealed a protruding thrombus in the left atrium and an emergency operation was performed. The protruding thrombus was found to originate from the scar that penetrated into the intra-atrial muscular septum caused by the PTMC. After removing the thrombus, the scar was covered with normal endothelium and the mitral valve was replaced with a 27-mm St. Jude Medical prosthetic valve. We think that the thromboembolism was caused by mitral valve restenosis, atrial fibrillation, and endothelial injury in the interatrial septum during PTMC. Therefore, long-term follow-up and appropriate medication is recommended after PTMC, since restenosis and thrombosis are likely to occur.
  Surgery Today 02/2003; 33(1):55-7. · 1.22 Impact Factor