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Biomedical subjects

Hiroshi Iwao

Publications and source records attributed to Hiroshi Iwao.

At least 19 recordsLinked to original sources
PubMed2006

Coronary flow velocity reserve measurement in three major coronary arteries using transthoracic Doppler echocardiography.

BACKGROUND: Measurement of the coronary flow velocity reserve (CFVR) by transthoracic Doppler echocardiography (TTDE) has been reported to be useful for the noninvasive assessment of significant coronary artery stenosis or myocardial ischemia. The purpose of this study was to evaluate the value of this method in three major coronary arteries for detecting myocardial ischemia in the clinical setting. METHODS: We studied 89 consecutive patients who were referred to our outpatient clinic because of chest pain. We measured CFVR using TTDE in three major coronary arteries. We defined CFVR<2.0 in at least one vessel as being positive for myocardial ischemia. The accuracy of CFVR measurements for detecting myocardial ischemia was determined in comparison with exercise thallium-201 (Tl-201) single photon emission computed tomography (SPECT) as a reference standard. RESULTS: CFVR in at least one vessel was successfully measured in 87 of 89 patients (98%). The sensitivity and specificity of CFVR<2.0 in at least one coronary vessel, in any of the coronary territories, was 86% and 89%, respectively. In terms of assessing myocardial ischemia in each coronary artery territory, the agreement between CFVR<2.0 and Tl-201 SPECT for the left anterior descending coronary artery, the posterior descending coronary artery, and the left circumflex coronary artery territories was 95%, 81%, and 73%, respectively. CONCLUSION: Noninvasive CFVR measurement by TTDE may be useful for detecting myocardial ischemia, as well as for identifying ischemic territories in the clinical setting.

Adenosine Triphosphate↗
PubMed2006

Effects of erythropoietin on cardiac remodeling after myocardial infarction.

Erythropoietin (EPO) has been suggested to have a cardioprotective effect against ischemia. The purpose of this study was to examine the effects of EPO on cardiac remodeling after myocardial infarction (MI). MI was induced by ligation of the coronary artery in Wistar rats. The rats with MI were randomly divided into untreated MI and two EPO-treated MI groups. EPO was administered subcutaneously by injection once a day for 4 days after MI at 5000 U/kg or 3 times a week for 4 weeks at 1000 U/kg. Five days after MI, EPO prevented the increase in activated caspase 3, matrix metalloproteinase-2, and transcriptional activation of activator protein-1 in non-infarcted myocardium. Four weeks after MI, left ventricular weight, left ventricular end-diastolic pressure, and left ventricular dimension were increased, and ejection fraction and E wave deceleration time were decreased. EPO significantly attenuated this ventricular remodeling and systolic and diastolic dysfunction. In addition, EPO significantly attenuated the interstitial fibrosis and remodeling-related gene expression in non-infarcted myocardium. Furthermore, EPO significantly enhanced angiogenesis and reduced apoptotic cell death in peri-infarcted myocardium. In conclusion, when administered after MI, EPO prevents cardiac remodeling and improves ventricular function with enhanced angiogenesis and reduced apoptosis.

Animals↗
PubMed2006

Smoking history and prior surgical resection predict sensitivity to gefitinib in advanced non-small-cell lung cancer.

BACKGROUND: Gefitinib is an inhibitor of epidermal growth factor receptor tyrosine kinase, and induces radiographic regression and symptomatic improvement in patients with non-small cell lung cancer (NSCLC). Phase II trials suggested female sex and adenocarcinoma were associated with response, never smoking history and adenocarcinoma were associated with survival. We attempted to identify additional clinical features associated with response and survival. METHODS: We reviewed medical records and imaging studies of all 68 NSCLC patients treated by gefitinib monotherapy in our institution. We identified patients experiencing disease control and compared their clinical features with those of other patients. We considered partial response, stable disease or incomplete response and stable disease to be evidence of disease control. Univariate and multivariate analysis were performed to determine predictive and prognostic factors associated with disease control and survival. RESULTS: Of 68 patients, 20 (29.4%) experienced disease control. Variables identified as significant for disease control with gefitinib included never smoking history (p=0.0128) and history of curative surgical resection (p=0.0007) on multivariate analysis. Variables identified as significant for overall survival included never smoking history (p=0.0128), history of curative surgical resection (p=0.0007), and performance status (PS) of 0 and 1 (p=0.0001) on multivariate analysis. CONCLUSIONS: Our findings suggest that never smoking history and history of curative surgical resection are key factors for disease control and prognostic factors in patients with NSCLC treated with gefitinib.

Adult↗
PubMed2005

Granulocyte-colony stimulating factor augments neovascularization induced by bone marrow transplantation in rat hindlimb ischemia.

Because granulocyte-colony stimulating factor (G-CSF) mobilizes bone marrow cells including endothelial progenitor cells, we examined whether G-CSF augments angiogenesis and collateral vessel formation induced by bone marrow-mononuclear cells transplantation (BMT). Unilateral hindlimb ischemia was surgically induced in Lewis rats. One week after surgery, administration of 100 mg/kg per day G-CSF significantly increased the laser Doppler blood perfusion index (LDBPI), number of angiographically detectable collateral vessels (angiographic score), and capillary density determined by alkaline phosphatase staining. In the BMT group (1 x 10(7) cells/rat) and the group with combined G-CSF treatment and BMT, LDBPI was significantly increased compared with that in the vehicle-treated group. In the BMT group, neovascularization was significantly increased as evidenced by the angiographic score and capillary density compared with the vehicle-treated group. Furthermore, the combination of G-CSF treatment and BMT augmented neovascularization compared with BMT alone, as evidenced by the angiographic score and capillary density. Moreover, G-CSF significantly increased vascular endothelial growth factor mRNA and fibroblast growth factor-2 mRNA in hindlimb muscle. In conclusion, G-CSF was found to augment neovascularization in rat hindlimb ischemia. Combined use of G-CSF treatment and BMT may be a useful strategy for therapeutic neovascularization in ischemic tissues.

Alkaline Phosphatase↗
PubMed2005

Beneficial effect of candesartan on rat diastolic heart failure.

In this study, we examined whether an angiotensin II type 1 (AT1)-receptor blocker improves diastolic heart failure (DHF) in Dahl salt-sensitive (DS) rats. DHF was prepared by feeding DS rats on 8% NaCl diet from 7 weeks of age. DHF was estimated with echocardiography by measuring E velocity / A velocity (E/A) of left ventricular inflow. DS rats with established DHF were orally given candesartan (1 mg/kg per day) or vehicle. After 13 days of treatment, candesartan significantly improved DHF, as shown by the reduction of E/A from 4.49 +/- 1.04 to 1.98 +/- 0.54 (P<0.05) and prolonged survival rate more than the vehicle. Cardiac fibrosis, apoptosis, and gene expression were estimated by Sirius Red-staining, TUNEL-staining, and Northern blot analysis, respectively. The improvement of DHF by candesartan was accompanied by the decrease in cardiac hypertrophy, fibrosis, and apoptosis, and the reduction of gene expression of brain natriuretic peptide, collagen I, and monocyte chemoattractant protein-1. Moreover, candesartan decreased cardiac inflammatory cells and reactive oxygen species, estimated by counting ED-1-positive cells and the measurement of 4-hydroxy-2-nonenal staining, respectively. These results indicate that candesartan can improve diastolic dysfunction and may slow the progression of cardiac remodelling in DS rats with established DHF.

Aldehydes↗
PubMed2005

Angiotensin blockade inhibits osteopontin expression in non-infarcted myocardium after myocardial infarction.

Osteopontin has been reported to have an important role in cardiac fibrosis. However, little is known about the effects of angiotensin-converting enzyme inhibitor (ACEI) and angiotensin type 1 receptor blockers (ARB) on osteopontin expression in infarcted myocardium. The purpose of this study was to elucidate the effects of an ACEI (perindpril) and an ARB (candesartan cilexitil) on cardiac function as assessed by Doppler echocardiography and cardiac osteopontin expression associated with cardiac remodeling in myocardial infarcted rats. ACEI or ARB was administered after myocardial infarction (MI). At 4 weeks after MI, cardiac function, and mRNAs in non-infarcted myocardium were analyzed. ACEI and ARB equally prevented left ventricular dilatation, reduction of ejection fraction, and the increase in E/A wave velocity ratio and the rate of E wave deceleration by MI. ACEI and ARB significantly suppressed increased mRNA expression of atrial natriuretic peptide, brain natriuretic peptide, osteopontin, and collagen I and III in the non-infarcted ventricle at 4 weeks. Immunohistochemically stained osteopontin was increased in interstitial fibrosis of non-infarcted myocardium. Both ACEI and ARB significantly prevented cardiac fibrosis and osteopontin expression. In conclusion, angiotensin blockade inhibits osteopontin expression in non-infarcted myocardium and prevents cardiac remodeling after MI.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2005

Important role of apoptosis signal-regulating kinase 1 in ischemia-induced angiogenesis.

OBJECTIVE: We first examined the role of apoptosis signal-regulating kinase 1 (ASK1), one of mitogen-activated protein kinase kinase kinases, in ischemia-induced angiogenesis. METHODS AND RESULTS: Unilateral hindlimb ischemia was induced surgically in C57BL/6J wild-type (WT) mice or mice deficient in ASK1 (ASK1(-/-)). ASK1 activity in WT mouse hindlimb was increased dramatically after ischemia. By laser Doppler analysis, well-developed collateral vessels and angiogenesis were observed in WT mice in response to hindlimb ischemia, whereas these responses were reduced in ASK1(-/-) mice. Immunostaining revealed that infiltration of macrophages and T lymphocytes was suppressed in the ischemic tissues of ASK1(-/-) mice compared with WT mice. The expression of vascular endothelial growth factor (VEGF) and monocyte chemoattractant protein-1 (MCP-1) proteins in ischemic tissues was weaker in ASK1(-/-) mice compared with WT mice. In vitro study on endothelial cells indicated that dominant-negative ASK1 significantly attenuated hydrogen peroxide-induced VEGF and MCP-1 production. Furthermore, in vivo blockade of MCP-1 by its neutralizing antibody suppressed the recovery of the blood flow and capillary formation after ischemia. CONCLUSIONS: ASK1 pathway promotes early angiogenesis by inducing inflammatory cell infiltration and VEGF and MCP-1 expression. ASK1 may provide the basis for the development of new therapeutic strategy for angiogenesis.

Animals↗
PubMed2005

Critical role of angiotensin II in excess salt-induced brain oxidative stress of stroke-prone spontaneously hypertensive rats.

BACKGROUND AND PURPOSE: The detailed role of angiotensin II in salt-exacerbated stroke is unclear. We examined the role of angiotensin II in salt-accelerated stroke of stroke-prone spontaneously hypertensive rats (SHRSP). METHODS: Salt-loaded SHRSP were orally given the angiotensin II type 1 (AT1) receptor blocker candesartan (0.3 to 3 mg/kg per day) and calcium channel blocker amlodipine (1 mg/kg per day), and the effects on stroke (n=61) and brain superoxide were compared between them. We also examined the effect of angiotensin II infusion (200 ng/kg per min) on brain superoxide production and blood-brain barrier. RESULTS: Despite the comparable hypotensive effect between candesartan and amlodipine, candesartan prolonged survival of salt-loaded SHRSP much more than amlodipine (P<0.01), being associated with more improvement of cerebral arteriolar thickening, cerebral arteriolar cell proliferation, and hippocampal CA1 neuronal cell reduction (1024.9+/-20.6 versus 724.9+/-22.8 cells/mm2; P<0.01; n=7 to 10 in each group) in SHRSP by candesartan (P<0.05) than amlodipine. Salt loading increased superoxide and NADPH oxidase activity in brain cortex and hippocampus of SHRSP, and this increase was prevented by candesartan (P<0.01) but not amlodipine. Angiotensin II infusion, via AT1 receptor, directly increased brain superoxide by 1.8-fold (P<0.05; n=6 to 7 in each group) and impaired blood-brain barrier in salt-loaded SHRSP by 1.7-fold (P<0.05), and this increase in brain superoxide and blood-brain barrier impairment was prevented by tempol as well as candesartan. CONCLUSIONS: Excess salt, via oxidative stress, accelerates stroke, and angiotensin II, via AT1 receptor, plays a pivotal role in brain superoxide production of SHRSP by excess salt.

Amlodipine↗
PubMed2005

Role of c-Jun NH2-terminal kinase in G-protein-coupled receptor agonist-induced cardiac plasminogen activator inhibitor-1 expression.

Plasminogen activator inhibitor-1 (PAI-1) has been implicated as a contributing risk factor for cardiovascular disease. However, little is known about molecular mechanisms of cardiac PAI-1 gene expression. To elucidate these mechanisms, dominant negative mutants of c-Jun NH(2)-terminal kinase (JNK), p38MAPK, apoptosis signal-regulating kinase-1 (ASK-1) and c-Jun were overexpressed in rat neonatal ventricular cardiac myocytes and fibroblasts by adenovirus vector to abrogate the activation of the corresponding endogenous proteins. One hundred nmol/l of angiotensin II significantly enhanced the JNK and p38MAPK activities of cardiomyocytes (2.3-fold and 1.9-fold, P < 0.05) and fibroblasts (3.2-fold and 2.5-fold, P < 0.05). At 3 h after stimulation, angiotensin II was found to have significantly increased PAI-1 mRNA, by 5.2-fold in cardiomyocytes and by 9.7-fold in fibroblasts. Dominant negative mutants of JNK, ASK-1 and c-Jun significantly inhibited PAI-1 mRNA expression and protein synthesis in both cardiomyocytes and fibroblasts, whereas a dominant negative mutant of p38MAPK did not change this expression. Moreover, a dominant negative mutant of JNK also significantly prevented the induction of PAI-1 mRNA expression by 100 nmol/l endothelin-1 and 10 micromol/l phenylephrine. In conclusion, G-protein-coupled receptor agonist-induced PAI-1 expression is partially mediated through JNK activation.

Angiotensin II↗
PubMed2005

Involvement of c-Jun NH2 terminal kinase and p38MAPK in rapamycin-mediated inhibition of neointimal formation in rat carotid arteries.

OBJECTIVE: Rapamycin-coated stents in coronary artery lesions have recently been shown to be effective in inhibiting neointimal formation. However, little is known about the effects of rapamycin on mitogen-activated protein kinase (MAPK), which is an important signal for neointimal formation. Therefore, we examined the effects of rapamycin on MAPK and transcriptional factors in cultured human coronary artery smooth muscle cells (CASMC) and in balloon-injured rat carotid arteries. METHODS AND RESULTS: Activation of ERK, JNK, p38MAPK, AP-1, and NF-kB in coronary artery smooth muscle cells was increased by 2% fetal bovine serum. Ten nmol/L of rapamycin prevented the activation of JNK, p38MAPK, AP-1, and NF-kB (65%, 65%, 67%, and 26% respectively, P<0.01). In an in vivo study, remarkable neointimal formation was observed 14 days after injury. Coating Pluronic gel with 20 and 50 mug rapamycin around the injured artery significantly decreased the intimal area/medial area ratio, compared with vehicle (0.75 vs. 1.2, P<0.01). Rapamycin prevented the increase in activation of JNK, p38MAPK, AP-1, and NF-kB in injured artery (42%, 70%, 75%, and 60% respectively, P<0.05). CONCLUSIONS: Neointimal formation after balloon injury is inhibited by rapamycin, which is partially mediated by inhibition of JNK and p38MAPK, followed by AP-1 and NF-kB.

Animals↗
PubMed2005

AP-1 and colorectal cancer.

Activator protein-1 (AP-1) is a transcription factor that consists of either a Jun-Jun homodimer or a Jun-Fos heterodimer. AP-1 regulates the expression of multiple genes essential for cell proliferation, differentiation and apoptosis. Numerous reports suggest that AP-1 plays an important role in various human diseases. Among them, the roles relating to human cancers have been strongly suggested for a long time. In human cancers, colorectal cancer is still a leading cause of morbidity and mortality in the world. Since there are some reports about the role of AP-1 in colorectal cancer response to a number of stimuli, such as cytokines and growth factors, and oncogenictransformation, therapeutic inhibition of AP-1 activity has attracted considerable interest. Here, we demonstrate the biological properties of AP-1 and its role in colorectal cancer, and discuss a possibility of an AP-1 inhibitor, an adenovirus dominant-negative mutant of c-Jun, as a therapeutic agent for gene therapy.

Animals↗
PubMed2005

Excess aldosterone under normal salt diet induces cardiac hypertrophy and infiltration via oxidative stress.

Aldosterone is known to play a role in the pathophysiology of some cardiovascular diseases. However, previous studies on aldosterone infusion have been mostly performed in animals receiving sodium loading and uninephrectomy, and thus the cardiac action of aldosterone alone remains to be fully clarified. The present study was undertaken to investigate the direct cardiac action of aldosterone infusion alone in rats not subjected to salt loading and uninephrectomy. Aldosterone (0.75 microg/h) was subcutaneously infused into rats via an osmotic minipump for 14 days. Aldosterone infusion, under a normal salt diet, induced only a slight increase in the blood pressure of normal rats throughout the infusion. However, aldosterone significantly induced cardiac hypertrophy, as shown by echocardiography and measurement of cardiomyocyte cross-sectional area. Furthermore, aldosterone caused not only cardiac interstitial macrophage infiltration but also cardiac focal inflammatory lesions, which were associated with an increase in cardiac monocyte chemoattractant protein-1 (MCP-1) and osteopontin mRNA. The slight elevation of blood pressure by aldosterone infusion was completely prevented by tempol, the superoxide dismutase mimetic. However, tempol failed to suppress cardiac hypertrophy, the formation of inflammatory lesions, and upregulation of cardiac MCP-1 and osteopontin by aldosterone, while N-acetylcysteine could inhibit all of them. Our data provide evidence that aldosterone alone can induce cardiac hypertrophy and severe inflammatory response in the heart, independently of blood pressure, even in the absence of salt loading or nephrectomy. Aldosterone seems to induce cardiac inflammation and gene expression via oxidative stress that is inhibited by N-acetylcysteine but not by tempol.

Acetylcysteine↗
PubMed2005

Relationship between vascular endothelial growth factor and angiopoietin-2 in asthmatics before and after inhaled beclomethasone therapy.

Vascular endothelial growth factor (VEGF) and Angiopoietin-2 (Ang-2) play complementary roles in the process of vascular remodeling. Therefore, this study was designed to examine an interaction between VEGF and Ang-2 in asthmatic airways. VEGF, Ang-2, and hepatocyte growth factor (HGF) levels in induced sputum obtained from 17 asthmatic patients and 10 normal control subjects were examined. Eight weeks of inhaled beclomethasone dipropionate (BDP) therapy (800 microg/day) was administered to all asthmatic patients, and sputum induction was repeated. VEGF, Ang-2, and HGF levels in induced sputum were significantly higher in asthmatic patients than in control subjects. Ang-2 levels were significantly correlated with VEGF levels but not with HGF levels. We also found that there was a significant correlation between airway vascular permeability index and VEGF levels but not HGF levels. In addition, VEGF/Ang-2 ratio in asthmatic patients was significantly higher than that in control subjects, and it was significantly correlated with airway vascular permeability index. After inhaled BDP therapy, VEGF levels were significantly decreased, but Ang-2 levels did not change. Therefore, VEGF/Ang-2 ratio after BDP therapy was markedly decreased to the same level as in the control subjects. Our findings suggest that interaction between VEGF and Ang-2 in asthmatic airways may exist and that high VEGF/Ang-2 ratio may be responsible for increased airway microvascular permeability. In addition, inhaled glucocorticoids therapy may reduce airway vascular permeability and remodeling via VEGF/Ang-2-dependent mechanism.

Administration, Inhalation↗
PubMed2004

Core protein of hepatitis C virus induces cardiomyopathy.

Hepatitis C virus (HCV) has been reported to be associated with cardiomyopathy. However, the mechanism of cardiomyopathy in chronic HCV infection is still unclear. Therefore, we investigate the development of cardiomyopathy in mice transgenic for the HCV-core gene. After the age of 12 months, mice developed cardiomyopathy that appeared as left ventricular dilatation, and systolic and diastolic dysfunction assessed by Doppler echocardiography. Histologically, hypertrophy of cardiomyocytes, cardiac fibrosis, disarray and scarcity of myofibrils, vacuolization and deformity of nuclei, myofibrillar lysis, streaming of Z-bands, and an increased number of bizarre-shaped mitochondria were found in HCV-core transgenic mice. These histological changes are just consistent with cardiomyopathy. In conclusion, the HCV-core protein directly plays an important role in the development of cardiomyopathy.

Actin Cytoskeleton↗
PubMed2004

Gene expression profile in experimental mesangial proliferative glomerulonephritis.

We analyzed gene expression in rat anti-Thy1 antibody-induced glomerulonephritis by using the cDNA microarray method. Ninety-seven genes that differed by more than 1.5-fold intensity in comparison with the controls were selected. Cluster analysis showed that the expression of genes associated with inflammation reached maximum levels at 24 h, while genes involved in the development of fibrosis increased at 7 days after injection. Microarray analysis of animal disease models may be a powerful approach for understanding the gene expression programs that underlie these disorders.

Animals↗