Details of a Researcher

Papers - ITOH Hiroshi

Division display 521 - 540 of about 549 ／ All the affair displays >>

[PPARgamma]

Itoh, H.

Nihon Rinsho 64 Suppl 5 182 - 91 2006.07

ISSN 0047-1852

[Idiopathic hyperaldosteronism (IHA)]

Miyashita, K., Itoh, H. and Nakao, K.

Nihon Rinsho Suppl 1 624 - 7 2006.05

ISSN 0047-1852

[ACTH-independent macronodular adrenal hyperplasia]

Miyashita, K., Itoh, H. and Nakao, K.

Nihon Rinsho Suppl 1 614 - 7 2006.05

ISSN 0047-1852

The neuroprotective and vasculo-neuro-regenerative roles of adrenomedullin in ischemic brain and its therapeutic potential

Miyashita, K., Itoh, H., Arai, H., Suganami, T., Sawada, N., Fukunaga, Y., Sone, M., Yamahara, K., Yurugi-Kobayashi, T., Park, K., Oyamada, N., Sawada, N., Taura, D., Tsujimoto, H., Chao, T. H., Tamura, N., Mukoyama, M. and Nakao, K.

Endocrinology 147 ( 4 ) 1642 - 53 2006.04

ISSN 0013-7227

Adrenomedullin (AM) is a vasodilating hormone secreted mainly from vascular wall, and its expression is markedly enhanced after stroke. We have revealed that AM promotes not only vasodilation but also vascular regeneration. In this study, we focused on the roles of AM in the ischemic brain and examined its therapeutic potential. We developed novel AM-transgenic (AM-Tg) mice that overproduce AM in the liver and performed middle cerebral artery occlusion for 20 min (20m-MCAO) to examine the effects of AM on degenerative or regenerative processes in ischemic brain. The infarct area and gliosis after 20m-MCAO was reduced in AM-Tg mice in association with suppression of leukocyte infiltration, oxidative stress, and apoptosis in the ischemic core. In addition, vascular regeneration and subsequent neurogenesis were enhanced in AM-Tg mice, preceded by increase in mobilization of CD34(+) mononuclear cells, which can differentiate into endothelial cells. The vasculo-neuro-regenerative actions observed in AM-Tg mice in combination with neuroprotection resulted in improved recovery of motor function. Brain edema was also significantly reduced in AM-Tg mice via suppression of vascular permeability. In vitro, AM exerted direct antiapoptotic and neurogenic actions on neuronal cells. Exogenous administration of AM in mice after 20m-MCAO also reduced the infarct area, and promoted vascular regeneration and functional recovery. In summary, this study suggests the neuroprotective and vasculo-neuro-regenerative roles of AM and provides basis for a new strategy to rescue ischemic brain through its multiple hormonal actions.

Access to Document (DOI)

Expression of the adrenomedullin gene in adipose tissue

Nambu, T., Arai, H., Komatsu, Y., Yasoda, A., Moriyama, K., Kanamoto, N., Itoh, H. and Nakao, K.

Regul Pept 132 ( 1-3 ) 17 - 22 2005.12

ISSN 0167-0115

Adrenomedullin (AM) is a potent vasodilating peptide originally isolated from human pheochromocytoma cells. This report concerns the expression and secretion of AM from adipose tissue. Northern blot analysis demonstrated marked expression of AM mRNA in mouse adipose tissue. Expression levels in adipose tissues were 2.5-3.2 times higher than in the kidney. AM mRNA level in mature adipocytes was 7.3 times higher than in the stroma-vascular fraction of adipose tissue. In mature adipocyte culture, time-dependent increase of AM peptide concentration in the culture medium was detected. AM expression was also detected in human subcutaneous adipose tissue. Adipose AM expression significantly increased in obesity mouse model, high-fat diet fed mice and ob/ob mice. These results suggest that adipose tissue, especially mature adipocytes, is major source of AM in the body, and that adipocyte-derived AM plays a pathophysiological role in obesity.

Access to Document (DOI)

Papillary thyroid carcinoma without metastases manifesting as an autonomously functioning thyroid nodule

Majima, T., Doi, K., Komatsu, Y., Itoh, H., Fukao, A., Shigemoto, M., Takagi, C., Corners, J., Mizuta, N., Kato, R. and Nakao, K.

Endocr J 52 ( 3 ) 309 - 16 2005.06

ISSN 0918-8959

A 59-year-old woman with papillary thyroid carcinoma inside of an autonomously functioning thyroid nodule is described in this report. The patient was referred to our clinic because of rapid weight loss and swelling on the left side of the neck. Ultrasonography of the thyroid demonstrated a nonhomogeneous nodule in the lower part of an enlarged left lobe. Both 99mTc and 123I thyroid scintigraphic imaging showed a hot area corresponding to the nodule with lower uptake in the remaining thyroid tissue. Histopathological examination of the nodule revealed papillary adenocarcinoma, and the immunohistochemistry proved weak but positive staining for triiodothyronine and thyroxine. Based on these findings, the nodule was diagnosed as a functioning papillary adenocarcinoma. Although thyroid carcinoma manifesting as a hot nodule on the radionuclide isotope scan is an extremely rare occurrence, the current case is clinically important because it suggests that the diagnosis of a hot nodule cannot always rule out thyroid carcinoma in the nodule, and that even a hot nodule requires careful management so that the malignancy is not overlooked.

Analysis of rat insulin II promoter-ghrelin transgenic mice and rat glucagon promoter-ghrelin transgenic mice

Iwakura, H., Hosoda, K., Son, C., Fujikura, J., Tomita, T., Noguchi, M., Ariyasu, H., Takaya, K., Masuzaki, H., Ogawa, Y., Hayashi, T., Inoue, G., Akamizu, T., Hosoda, H., Kojima, M., Itoh, H., Toyokuni, S., Kangawa, K. and Nakao, K.

J Biol Chem 280 ( 15 ) 15247 - 56 2005.04

ISSN 0021-9258

We developed and analyzed two types of transgenic mice: rat insulin II promoter-ghrelin transgenic (RIP-G Tg) and rat glucagon promoter-ghrelin transgenic mice (RGP-G Tg). The pancreatic tissue ghrelin concentration measured by C-terminal radioimmunoassay (RIA) and plasma desacyl ghrelin concentration of RIP-G Tg were about 1000 and 3.4 times higher than those of nontransgenic littermates, respectively. The pancreatic tissue n-octanoylated ghrelin concentration measured by N-terminal RIA and plasma n-octanoylated ghrelin concentration of RIP-G Tg were not distinguishable from those of nontransgenic littermates. RIP-G Tg showed suppression of glucose-stimulated insulin secretion. Arginine-stimulated insulin secretion, pancreatic insulin mRNA and peptide levels, beta cell mass, islet architecture, and GLUT2 and PDX-1 immunoreactivity in RIP-G Tg pancreas were not significantly different from those of nontransgenic littermates. Islet batch incubation study did not show suppression of insulin secretion of RIP-G Tg in vitro. The insulin tolerance test showed lower tendency of blood glucose levels in RIP-G Tg. Taking lower tendency of triglyceride level of RIP-G Tg into consideration, these results may indicate that the suppression of insulin secretion is likely due to the effect of desacyl ghrelin on insulin sensitivity. RGP-G Tg, in which the pancreatic tissue ghrelin concentration measured by C-RIA was about 50 times higher than that of nontransgenic littermates, showed no significant changes in insulin secretion, glucose metabolism, islet mass, and islet architecture. The present study raises the possibility that desacyl ghrelin may have influence on glucose metabolism.

Access to Document (DOI)

Angiotensin II suppresses growth arrest specific homeobox (Gax) expression via redox-sensitive mitogen-activated protein kinase (MAPK)

Saito, T., Itoh, H., Yamashita, J., Doi, K., Chun, T. H., Tanaka, T., Inoue, M., Masatsugu, K., Fukunaga, Y., Sawada, N., Sakaguchi, S., Arai, H., Tojo, K., Tajima, N., Hosoya, T. and Nakao, K.

Regul Pept 127 ( 1-3 ) 159 - 67 2005.04

ISSN 0167-0115

Oxidative stress is known to be involved in growth control of vascular smooth muscle cells (VSMCs). We and others have demonstrated that angiotensin II (Ang II) has an important role in vascular remodeling. Several reports suggested that VSMC growth induced by Ang II was elicited by oxidative stress. Gax, growth arrest-specific homeobox is a homeobox gene expressed in the cardiovascular system. Over expression of Gax is demonstrated to inhibit VSMC growth. We previously reported that Ang II down-regulated Gax expression. To address the regulatory mechanism of Gax, we investigated the significance of oxidative stress in Ang II-induced suppression of Gax expression. We further examined the involvement of mitogen-activated protein kinases (MAPKs), which is crucial for cell growth and has shown to be activated by oxidative stress, on the regulation of Gax expression by Ang II. Ang II markedly augmented intracellular H2O2 production which was decreased by pretreatment with N-acetylcystein (NAC), an anti-oxidant. Ang II and H2O2 decreased Gax expression dose-dependently and these effects were blocked by administration of both NAC and pyrrolidine dithiocarbamate (PDTC), another anti-oxidant. Ang II and H2O2 induced marked activation of extracellular signal-responsive kinase1/2 (ERK1/2), which was blocked by NAC. Ang II and H2O2 also activated p38MAPK, and they were blocked by pre-treatment with NAC. However, the level of activated p38MAPK was quite low in comparison with ERK1/2. Ang II- or H2O2 -induced Gax down-regulation was significantly inhibited by PD98059, an ERK1/2 inhibitor but not SB203580, a p38MAPK inhibitor. The present results demonstrated the significance of regulation of Gax expression by redox-sensitive ERK1/2 activation.

Access to Document (DOI)

[PPARs and hypertension]

Itoh, H.

Nihon Rinsho 63 ( 4 ) 631 - 42 2005.04

ISSN 0047-1852

PPARs (peroxisome proliferator-activated receptors) alpha, delta and gamma are expressed in adipocytes, skeletal myocytes and hepatocytes and also in endothelial cells, vascular smooth muscle cells and monocytes/macrophages, in distinct distributions. They are critically involved in the pathophysiology of obesity, diabetes, hyperlipidemia and hypertension, the complex of which is recognized as "metabolic syndrome", as well as, of their vascular complications. In addition to modulation of insulin sensitivity, PPARs can regulate oxidative stress and local production of various vasoactive substances in blood vessels, and thus control vascular tone and remodeling as one of the determinants of hypertension.

[Renin-angiotensin system and metabolic domino]

Itoh, H.

Nihon Rinsho 63 Suppl 3 180 - 7 2005.03

ISSN 0047-1852

Therapeutic potential of thiazolidinediones in activation of peroxisome proliferator-activated receptor gamma for monocyte recruitment and endothelial regeneration

Tanaka, T., Fukunaga, Y., Itoh, H., Doi, K., Yamashita, J., Chun, T. H., Inoue, M., Masatsugu, K., Saito, T., Sawada, N., Sakaguchi, S., Arai, H. and Nakao, K.

Eur J Pharmacol 508 ( 1-3 ) 255 - 65 2005.01

ISSN 0014-2999

Thiazolidinediones, a new class of antidiabetic drugs that increase insulin sensitivity, have been shown to be ligands for peroxisome proliferator-activated receptor gamma (PPARgamma). Recent studies demonstrating that PPARgamma occurs in macrophages have focused attention on its role in macrophage functions. In this study, we investigated the effect of thiazolidinediones on monocyte proliferation and migration in vitro and the mechanisms involved. In addition, we examined the therapeutic potentials of thiazolidinediones for injured atherosclerotic lesions. Troglitazone and pioglitazone, the two thiazolidinediones, as well as 15-deoxy-delta12,14-prostaglandin J2 inhibited in a dose-dependent manner the serum-induced proliferation of THP-1 (human monocytic leukemia cells) and of U937 (human monoblastic leukemia cells), which permanently express PPARgamma. These ligands for PPARgamma also significantly inhibited migration of THP-1 induced by monocyte chemoattractant protein-1 (MCP-1). Troglitazone and 15-deoxy-delta12,14-prostaglandin J2 significantly suppressed the mRNA expression of the MCP family-specific receptor CCR2 (chemokine CCR2 receptor) in THP-1 at the transcriptional level. Furthermore, troglitazone significantly inhibited MCP-1 binding to THP-1. Oral administration of troglitazone to Watanabe heritable hyperlipidemic (WHHL) rabbits after balloon injury suppressed acute recruitment of monocytes/macrophages and accelerated re-endothelialization. These results suggest that thiazolidinediones have therapeutic potential for the treatment of diabetic vascular complications.

Access to Document (DOI)

[Clinical application of adrenomedullin to therapeutic angiogenesis]

Miyashita, K., Itoh, H. and Nakao, K.

Nihon Rinsho 62 Suppl 9 307 - 13 2004.09

ISSN 0047-1852

[Natriuretic peptides and atherosclerosis]

Yamahara, K., Itoh, H. and Nakao, K.

Nihon Rinsho 62 Suppl 9 117 - 20 2004.09

ISSN 0047-1852

[Current status and future prospects of C-type natriuretic peptide]

Park, K., Itoh, H. and Nakao, K.

Nihon Rinsho 62 Suppl 9 151 - 6 2004.09

ISSN 0047-1852

[Significant roles of natriuretic peptides in vascular physiology]

Miyashita, K., Itoh, H. and Nakao, K.

Nihon Rinsho 62 Suppl 9 51 - 5 2004.09

ISSN 0047-1852

[Involvement of PPARgamma in the pathogenesis of hypertension and hypertensive target-organ damage]

Itoh, H.

Nihon Rinsho 62 Suppl 3 179 - 90 2004.03

ISSN 0047-1852

[What is 'metabolic domino effect'?--new concept in lifestyle-related diseases]

Itoh, H.

Nihon Rinsho 61 ( 10 ) 1837 - 43 2003.10

ISSN 0047-1852

Lifestyle-related diseases such as hypertension, hyperlipidemia, and impaired glucose tolerance are independent risk factors for cardiovascular diseases. When these risk factors accumulate, the risk of cardiovascular diseases remarkably increases. This condition, marked by an accumulation of these risk factors in one person, is considered a disease entity by itself called the 'metabolic syndrome'. The effects of this syndrome over time are now being referred to as 'metabolic domino effect'. This new concept considers factors such as the flow of time and the chain reaction of the risk factors. When these risk factors accumulate in one person over time, the risk factors interact and multiply the cardiovascular risk, leading to a process similar to falling dominoes; once the process begins, it leads to cardiovascular diseases that are irreversible. Data strongly suggests that angiotensin II is a contributing factor at every step of the process in this metabolic domino effect, starting from obesity to the progression of macroangiopathy and microangiopathy. The key to effectively preventing cardiovascular diseases is to suppress production of angiotensin II at an early stage of the metabolic syndrome.

Successful treatment of primary aldosteronism due to computed tomography-negative microadenoma

Nishizawa, K., Nakamura, E., Kobayashi, T., Kamoto, T., Terai, A., Terachi, T., Ogawa, O., Itoh, H. and Nakao, K.

Int J Urol 10 ( 10 ) 544 - 6 2003.10

ISSN 0919-8172

We report a case of aldosterone-producing microadenoma that was correctly diagnosed and thus treated less invasively by laparoscopic adrenalectomy. A 58-year-old woman presented with palpitation and muscular weakness. She exhibited hypertension, hypokalemia and increased aldosterone excretion with suppressed renin activity. Therefore, primary aldosteronism was suggested. Although adrenal scintigram and computed tomography findings in the adrenal glands were normal, adrenal venous sampling tests indicated an overproduction of aldosterone in the right adrenal gland. We diagnosed an aldosterone-producing microadenoma in the right adrenal gland and performed an adrenalectomy. The patient became normotensive postoperatively and histopathological examination demonstrated a microadenoma, 5 mm in diameter.

[Significance of renin-angiotensin system in diabetes mellitus with hypertension]

Itoh, H.

Nihon Rinsho 61 ( 7 ) 1145 - 53 2003.07

ISSN 0047-1852

Diabetes mellitus and hypertension frequently occur in the same individual, based upon 'insulin resistance', which is caused by obesity and impairment of secretion of several adipocyte-derived hormones(adipocytokines), including leptin and adiponectin. Insulin resistance and activation of tissue renin-angiotensin system mutually affect each other to promote diabetes mellitus/hypertension and their complications. Especially, renin-angiotensin system in the adipose tissue modulate adipocyte differentiation and adipose tissue mass. Vascular renin-angiotensin system causes endothelial dysfunction and promotes inflammatory process to accelerate atherosclerosis. Blockade of renin-angiotensin system is reasonable for prevention and suppression of diabetes mellitus/hypertension and their complications.

Modification of GATA-2 transcriptional activity in endothelial cells by the SUMO E3 ligase PIASy

Chun, T. H., Itoh, H., Subramanian, L., Iniguez-Lluhi, J. A. and Nakao, K.

Circ Res 92 ( 11 ) 1201 - 8 2003.06

ISSN 0009-7330

GATA sequences are required for the optimal expression of endothelial cell-specific genes, including endothelin-1 (ET-1). We have identified PIASy in a search for new GATA-2 interacting proteins that can regulate GATA-2-mediated endothelial gene expression. Notably, among the cell populations comprising vascular walls, PIASy mRNA is selectively expressed in endothelial cells, and its expression can be regulated by angiogenic growth factors. We show that GATA-2 is covalently modified by small ubiquitin-like modifier (SUMO)-1 and -2 and that PIASy, through its E3 SUMO ligase activity, preferentially enhances the conjugation of SUMO-2 to GATA-2. Through a functional analysis, we demonstrate that PIASy potently suppresses the activity of the GATA-2-dependent human ET-1 promoter in endothelial cells. The suppressive effect of PIASy requires the GATA-binding site in the ET-1 promoter and depends on its interaction with GATA-2, which requires both N-terminal (amino acids 1-183) and C-terminal (amino acids 414-510) sequences in PIASy. We conclude that PIASy enhances the conjugation of SUMO-2 to GATA-2 and that the interaction of PIASy with GATA-2 can modulate GATA-mediated ET-1 transcription activity in endothelial cells through a RING-like domain-independent mechanism.

Access to Document (DOI)

　 Previous page - Next page 　