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Biomedical subjects

Muneyasu Saito

Publications and source records attributed to Muneyasu Saito.

12 recordsLinked to original sources
PubMed2003

Src family kinases and nitric oxide production are required for hepatocyte growth factor-stimulated endothelial cell growth.

Hepatocyte growth factor (HGF) is a potent mitogen for vascular endothelial cells (EC); however, signal transduction pathways for HGF-stimulated EC growth remain unclear. In the present study we investigated the role of Src family kinases and nitric oxide (NO) in HGF-stimulated EC growth. Human umbilical vein endothelial cells (HUVEC) were stimulated with HGF and NO was measured by an NOx analyzing HPLC system. Activation of ERK1/2 and p38 MAPK was assessed by Western blot. NO production in HUVEC increased 1.8-fold by HGF. A Src family kinases inhibitor PP1 inhibited HGF-stimulated NO production by 71%. HUVEC growth increased 1.9-fold in cell number by HGF. PP1 and Nitro-L-arginine methylester (L-NAME) inhibited HGF-stimulated HUVEC growth by 51 and by 71%. ERK1/2 and p38 MAPK were phosphorylated by HGF and a MEK inhibitor PD98059 and a p38 MAPK inhibitor SB203580 inhibited HGF-stimulated HUVEC growth by 66% and by 58%; however, HGF-induced phosphorylation of ERK1/2 and p38 MAPK was not inhibited by L-NAME, indicating that NO is not an upstream activator of ERK1/2 and p38 MAPK. These findings demonstrated that Src family kinases regulate HGF-stimulated NO production in HUVEC and that HGF stimulates HUVEC growth through NO-dependent and NO-independent pathways.

Analysis of Variance↗
PubMed2003

Exercise training in patients with chronic heart failure improves endothelial function predominantly in the trained extremities.

The present study investigates whether lower-limb dominant exercise training in patients with chronic heart failure (CHF) improves endothelial function primarily in the trained lower extremities or equally in the upper and lower extremities. Twenty-eight patients with CHF were randomized to the exercise or control group. The exercise group underwent cycle ergometer training for 3 months while controls continued an inactive sedentary lifestyle. Exercise capacity (6-min walk test) and flow-mediated vasodilation in the brachial and posterior tibial arteries were evaluated. After 3 months, walking performance increased only in the exercise group (488+/-16 to 501+/-14 m [control]; 497+/-23 to 567+/-39 m [exercise, p<0.05]). The flow-mediated vasodilation in the brachial arteries did not change in either group (4.2+/-0.5 to 4.5+/-0.4% [control]; 4.3+/-0.5 to 4.6+/-0.4% [exercise]), but that in the posterior tibial arteries increased only in the exercise group (4.1+/-0.5 to 4.1+/-0.3% [control]; 3.6+/-0.3 to 6.4+/-0.6% [exercise, p<0.01]). Cycle ergometer training improved flow-mediated vasodilation in the trained lower limbs, but not in the untrained upper limbs. Exercise training appears to correct endothelial dysfunction predominantly by a local effect in the trained extremities.

Arm↗
PubMed2003

Influence of contrast ultrasonography with perflutren lipid microspheres on microvessel injury.

Microbubbles have been reported to enhance ultrasound (US)-related side effects in animal systems. The present study investigated the influence of contrast ultrasonography (US) with perflutren lipid microspheres, a recently developed second-generation contrast agent, on microvessels. Rat mesentery was exposed to 1.8-MHz pulsed US with intravenous injection of perflutren (0.1 or 1.0 ml/kg) or Levovist (300 mg/kg), and the microvessel bleeding and endothelial cell injury was examined. Impaired endothelial cells were identified by the fluorescence of propidium iodide. Microvessel bleeding was examined also in the rat myocardium. The interaction between 0.1 ml/kg of perflutren and US exposure did not cause microvessel bleeding, and did not increase endothelial cell injury compared with the sham operation, unless frequent, strong US exposure occurred. When the dose was increased to 1.0 ml/kg, the combination of perflutren and US exposure resulted in capillary bleeding and increased endothelial cell injury in capillaries and venules (p<0.01). However, the incidence of microvessel bleeding and endothelial cell injury did not exceed that with Levovist microbubbles. In the myocardium, microvessel bleeding was not observed under any conditions. In conclusion, perflutren lipid microspheres enhanced US-related microvessel injury as with other contrast agents at the dose of 1.0 ml/kg, but not with 0.1 ml/kg and the appropriate US setting.

Animals↗
PubMed2003

[Exercise testing].

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Electrocardiography↗
PubMed2003

[Transient retinopathy after acute myocardial infarction treated by reperfusion therapy: clinical background and manifestation].

OBJECTIVES: The severe inflammatory reaction caused by acute myocardial infarction and reperfusion affects both the heart and other remote organs. The occurrence of retinopathy was evaluated in patients with acute myocardial infarction who underwent reperfusion therapy. METHODS: We investigated 29 patients with first acute myocardial infarction who underwent successful reperfusion therapy within 24 hr of the onset. Ophthalmic examinations including visual acuity test and ocular fundoscopy were performed within 3 days, 2 weeks, and then monthly up to 3 months after the onset of acute myocardial infarction. Plasma levels of intercellular adhesion molecule-1(ICAM-1), interleukin-6 and high sensitivity C-reactive protein were measured on admission. RESULTS: Soft exudates around the optic disc appeared in 17(58.6%) of the 29 patients, among whom 5 also developed superficial hemorrhages(17.2%). The retinopathy became most remarkable between 1 to 2 months after the onset of acute myocardial infarction and then faded away without any specific treatment. None of the patients had impairment of visual acuity, although 4 of the 17 patients with retinopathy complained of either blurred vision or metamorphopsia. Hypertension and/or diabetes mellitus tended to be more common in the retinopathy group than in the non-retinopathy group(59% vs 33%, p = 0.096). Plasma ICAM-1 levels were significantly higher than in the non-retinopathy group than in the retinopathy group(p = 0.017). There was no significant difference in plasma levels of interleukin-6 and high sensitivity C-reactive protein between the two groups. CONCLUSIONS: Retinopathy may occur after reperfusion for acute myocardial infarction. The dominant manifestation is transient soft exudates reflecting spotty retinal ischemia, probably due to microvascular obstruction.

Adult↗
PubMed2002

Endothelial cell injury in venule and capillary induced by contrast ultrasonography.

The aim of the present study was to test the hypothesis that microvascular endothelial cells (EC) are subject to the bioeffects induced by contrast ultrasound (US) because of their proximity to the circulating microbubbles. We examined EC injury in each microvessel section (arteriole, capillary or venule) in rat mesenteries among the following five groups: three controls (sham operation, microbubble injection alone, US exposure with saline injection), and two contrast-US groups (US exposure at a 1-Hz or 30-Hz frame rate with microbubble injection). Propidium iodide (PI), a fluorescent indicator of cell injury, was employed to visualize impaired EC. PI-positive nuclei were equally few among the three controls. Contrast-US increased PI-positive cells in capillaries (1-Hz frame rate, 2.4 +/- 2.2 cells per 0.1-mm vessel length, p = 0.09; 30-Hz frame rate, 4.3 +/- 1.8 cells, p < 0.01) and in venules (1-Hz frame rate, 4.1 +/- 2.5 cells, p < 0.05; 30-Hz frame rate, 13.8 +/- 3.6 cells, p < 0.01) compared with sham operation (0.10 +/- 0.22 cells). The finding indicates that diagnostic contrast US potentially causes EC injury, particularly in venules and capillaries.

Analysis of Variance↗
PubMed2002

Nicorandil and leukocyte activation.

Nicorandil, a hybrid compound of an ATP-sensitive potassium (KATP ) channel opener and a nitric oxide donor, has been reported to preserve microvascular integrity in patients with reperfused myocardial infarction. The aim of the current study was to test the hypothesis that nicorandil suppresses activation of polymorphonuclear leukocytes (PMNLs), resulting in reduction of PMNL migration into tissue upon ischemia/reperfusion. Nicorandil, along with the mitochondrial KATP channel opener diazoxide and the nitric oxide donors nitroglycerin and isosorbide dinitrate, suppressed pseudopod projection in human PMNLs treated with 10(-9)-formyl-methionyl-leucyl-phenylalanine (FMLP) and subjected to shear stress (5 dyn/cm(2)) with a cone-and-plate shear device. Suppression by nicorandil and diazoxide was reversed by KATP channel blockers, 5 hydroxydecanoate and glibenclamide. FMLP-induced increase of [Ca2+] in PMNLs was suppressed by nicorandil and diazoxide, and 5 hydroxy-decanoate and glibenclamide reversed this suppression. Results of reverse transcription polymerase chain reaction with rat PMNL mRNA indicated the presence of mRNAs of Kir6.2 and Kir6.1 but not mRNAs of sulfonylurea receptor 1 or 2. Isosorbide dinitrate, diazoxide, and nicorandil reduced leukocyte migration and microvascular obstruction in reperfused ischemic tissue of rat mesenteric microcirculation. In conclusion, nicorandil attenuates ischemia/reperfusion-induced PMNL activation via donation of nitric oxide and K channel-related cascade.

Animals↗
PubMed2002

Rupture of the anterolateral papillary muscle caused by a single diagonal branch obstruction.

This report presents the first case of anterolateral papillary muscle rupture caused by a diagonal branch occlusion only. Although the patient was in shock on admission, he was successfully treated by emergency surgery after hemodynamic stabilization by a percutaneous cardiopulmonary support system. This case implies that the anterolateral papillary muscle has a single blood supply and that it can rupture by an occlusion of only one diagonal branch even after balloon angioplasty.

Aged↗
PubMed2002

[Serotonin receptor blockade effective for postprandial vasospastic angina associated with dumping syndrome after esophagectomy: a case report].

A 49-year-old woman was admitted to our hospital because of frequent postprandial esophageal angina. After successful pyloric plasty, chest oppression lasting 5 to 15 min developed postprandially as well as symptoms of dumping syndrome. Electrocardiography showed ST-segment elevation in the II, III, aVf and precordial leads (V2 to V6). Finally, giant positive T waves and U waves were uniquely noted in the V1 to V5 leads. Intracoronary administration of acetylcholine (20 micrograms) provoked severe diffuse spasm in both right and left coronary arteries, chest pain and ST elevation. The conventional treatment for vasospastic angina, such as Ca2+ antagonists, nitrates and K channel opener, achieved no response. However, the combination with serotonergic receptor blockade reduced anginal attack. These findings suggest that the spastic angina in this case was partly caused by serotonin.

Angina Pectoris↗