Researchers Database

ichihara sahoko

    EnviromentalandPreventiveMedicine Professor
Last Updated :2021/12/04

Researcher Information

Degree

  • MD, PhD(Nagoya University)

URL

J-Global ID

Research Interests

  • 産業医学   環境医学   心毒性学   循環器病学   Social Life Science   Cardiac toxicology   

Research Areas

  • Life sciences / Cardiology
  • Life sciences / Hygiene and public health (non-laboratory)
  • Life sciences / Hygiene and public health (laboratory)
  • Life sciences / Hygiene and public health (non-laboratory)
  • Life sciences / Hygiene and public health (laboratory)
  • Life sciences / Healthcare management, medical sociology

Education

  •        - 2001/03  名古屋大学大学院  医学研究科
  • 1984/03 - 1990/04  Nagoya University  School of Medicine  医学科
  •        - 1990  Nagoya University  Faculty of Medicine

Association Memberships

  • THE JAPANESE SOCIETY FOR HYGIENE   JAPAN SOCIETY FOR OCCUPATIONAL HEALTH   THE JAPANESE SOCIETY OF TOXICOLOGY   日本人類遺伝学会   日本内科学会   日本循環器学会   

Published Papers

  • Fukatsu H, Koide N, Tada-Oikawa S, Izuoka K, Ikegami A, Ichihara S, Ukaji T, Morita N, Naiki Y, Komatsu T, Umezawa K
    Molecular medicine reports 1791-2997 2018/10 [Refereed][Not invited]
  • Kitamura Y, Kojima M, Kurosawa T, Sasaki R, Ichihara S, Hiraku Y, Tomimoto H, Murata M, Oikawa S
    Neuroscience 392 121 - 128 0306-4522 2018/09 [Refereed][Not invited]
  • Guoliang Li, Lihong Liang, Jingchao Yang, Lihai Zeng, Zhiwei Xie, Yizhou Zhong, Xiaolin Ruan, Ming Dong, Zhanhong Yang, Guanchao Lai, Weixin Huang, Aichu Yang, Jiabing Chen, Banghua Wu, Huaming Xu, Dezhi Meng, Shijie Hu, Lihua Xia, Xingfen Yang, Laiyu Li, Sahoko Ichihara, Gaku Ichihara, Hanlin Huang, Zhenlie Huang
    Nanotoxicology 12 (6) 571 - 585 1743-5390 2018/08 [Refereed][Not invited]
     
    Calcium carbonate nanomaterials (nano-CaCO3) are widely used in both manufacturing and consumer products, but their potential health hazards remain unclear. The objective of this study was to survey workplace exposure levels and health effects of workers exposed to nano-CaCO3. Personal and area sampling, as well as real-time and dust monitoring, were performed to characterize mass exposure, particle size distribution, and particle number exposure. A total of 56 workers (28 exposed workers and 28 unexposed controls) were studied in a cross-sectional study. They completed physical examinations, spirometry, and digital radiography. The results showed that the gravimetric nano-CaCO3 concentration was 5.264 ± 6.987 mg/m3 (0.037-22.192 mg/m3) at the workplace, and 3.577 ± 2.065 mg/m3 (2.042-8.161 mg/m3) in the breathing zone of the exposed workers. The particle number concentrations ranged from 8193 to 39 621 particles/cm3 with a size range of 30-150 nm. The process of packing had the highest gravimetric and particle number concentrations. The particle number concentration positively correlated with gravimetric concentrations of nano-CaCO3. The levels of hemoglobin, creatine phosphokinase (CK), lactate dehydrogenase, and high-density lipoprotein cholesterol (HDL-C) in the nano-CaCO3 exposure group increased significantly, but the white blood cell count (WBC), Complement 3 (C3), total protein (TP), uric acid, and creatinine (CREA) all decreased significantly. The prevalence rate of pulmonary hypofunction was significantly higher (p = 0.037), and the levels of vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, peak expiratory flow and forced expiratory flow 25% (FEF 25%), FEF 25-75% were negatively correlated with gravimetric concentrations of nano-CaCO3 (p < 0.05). Logistic analysis showed that nano-CaCO3 exposure level was associated with pulmonary hypofunction (p = 0.005). Meanwhile, a dose-effect relationship was found between the accumulated gravimetric concentrations of nano-CaCO3 and the prevalence rate of pulmonary hypofunction (p = 0.048). In conclusion, long-term and high-level nano-CaCO3 exposure can induce pulmonary hypofunction in workers. Thus, lung function examination is suggested for occupational populations with nano-CaCO3 exposure. Furthermore, future health protection efforts should focus on senior workers with accumulation effects of nano-CaCO3 exposure.
  • Yuka Yokoyama, Nathan Mise, Yuka Suzuki, Saeko Tada-Oikawa, Kiyora Izuoka, Lingyi Zhang, Cai Zong, Akira Takai, Yoshiji Yamada, Sahoko Ichihara
    International Journal of Molecular Sciences 19 (4) 1422-0067 2018/04 [Refereed][Not invited]
     
    Smoking increases the risk of atherosclerosis-related events, such as myocardial infarction and ischemic stroke. Recent studies have examined the expression levels of altered microRNAs (miRNAs) in various diseases. The profiles of tissue miRNAs can be potentially used in diagnosis or prognosis. However, there are limited studies on miRNAs following exposure to cigarette smoke (CS). The present study was designed to dissect the effects and cellular/molecular mechanisms of CS-induced atherosclerogenesis. Apolipoprotein E knockout (ApoE KO) mice were exposed to CS for five days a week for two months at low (two puffs/min for 40 min/day) or high dose (two puffs/min for 120 min/day). We measured the area of atherosclerotic plaques in the aorta, representing the expression of miRNAs after the exposure period. Two-month exposure to the high dose of CS significantly increased the plaque area in aortic arch, and significantly upregulated the expression of atherosclerotic markers (VCAM-1, ICAM-1, MCP1, p22phox, and gp91phox). Exposure to the high dose of CS also significantly upregulated the miRNA-155 level in the aortic tissues of ApoE KO mice. Moreover, the expression level of miR-126 tended to be downregulated and that of miR-21 tended to be upregulated in ApoE KO mice exposed to the high dose of CS, albeit statistically insignificant. The results suggest that CS induces atherosclerosis through increased vascular inflammation and NADPH oxidase expression and also emphasize the importance of miRNAs in the pathogenesis of CS-induced atherosclerosis. Our findings provide evidence for miRNAs as potential mediators of inflammation and atherosclerosis induced by CS.
  • Xiao Zhang, Cai Zong, Lingyi Zhang, Edwin Garner, Shigeyuki Sugie, Chinyen Huang, Wenting Wu, Jie Chang, Toshihiro Sakurai, Masashi Kato, Sahoko Ichihara, Shinji Kumagai, Gaku Ichihara
    Toxicological sciences : an official journal of the Society of Toxicology 162 (2) 559 - 569 1096-6080 2018/04 [Refereed][Not invited]
     
    1,2-Dichloropropane (1,2-DCP) has been used as a paint remover in the industry. The International Agency for Research on Cancer reclassified this compound recently to group 1 (carcinogenic to humans) based on epidemiological studies of cholangiocarcinoma among offset-color proof-printing workers exposed to 1,2-DCP in Japan. Two-year rodent carcinogenicity bioassays demonstrated that 1,2-DCP induced tumors in liver and lung, but not in bile duct. The present study was designed to assess the toxic effects of 1,2-DCP on proliferation and apoptosis in mice bile duct and the role of cytochrome P450 (CYP450) in any such effect. Male C57BL/6JJcl mice were cotreated or untreated with 1-aminobenzotriazole (1-ABT), a CYP450 inhibitor, and exposed to inhalation of 1,2-DCP at 0, 50, or 250 ppm alone, or at 0, 50, 250, or 1250 ppm 8 h/day for 4 weeks. Exposure to 1,2-DCP increased proliferation and apoptosis of cholangiocytes and induced severe hepatic damage, but had no effect on the lungs. Cotreatment with 1-ABT abrogated the effects of 1,2-DCP on proliferation and apoptosis of cholangiocytes. The results revealed that 1,2-DCP induces proliferation and apoptosis of cholangiocytes and that this effect is mediated through CYP450.
  • Kentaro Kuzuya, Sahoko Ichihara, Yuka Suzuki, Chisa Inoue, Gaku Ichihara, Syota Kurimoto, Shinji Oikawa
    PloS one 13 (2) e0192624  2018 [Refereed][Not invited]
     
    Given the hypothesis that inflammation plays a critical role in the progression of cardiovascular diseases, the aim of the present study was to identify new diagnostic and prognostic biomarkers of myocardial proteins involved in early-phase cardiac impairment, using proteomics analysis. Using the two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) combined with MALDI-TOF/TOF tandem mass spectrometry, we compared differences in the expression of proteins in the whole left ventricles between control hamsters, dilated cardiomyopathic hamsters (TO-2), and hypertrophy cardiomyopathic hamsters (Bio14.6) at 6 weeks of age (n = 6, each group). Proteomic analysis identified 10 protein spots with significant alterations, with 7 up-regulated and 3 down-regulated proteins in the left ventricles of both TO-2 and Bio 14.6 hamsters, compared with control hamsters. Of the total alterations, peroxiredoxin 2 (PRDX2) showed significant upregulation in the left ventricles of TO-2 and Bio 14.6 hamsters. Our data suggest that PRDX2, a redox regulating molecule, is involved in early-phase left ventricular impairment in hamsters with cardiomyopathy.
  • Sahoko Ichihara, Yuka Suzuki, Jie Chang, Kentaro Kuzuya, Chisa Inoue, Yuki Kitamura, Shinji Oikawa
    SCIENTIFIC REPORTS 7 (1) 9243  2045-2322 2017/08 [Refereed][Not invited]
     
    Inflammation enhanced by accumulation of reactive oxygen species plays an essential role in the progression of cardiovascular diseases. Using the 2D-oxyblot analysis and 2D-difference image gel electrophoresis (2D-DIGE), we compared the levels of ROS-induced carbonyl modification of myocardial proteins in the whole left ventricles between 6-week-old hamsters with dilated (TO-2) and hypertrophic cardiomyopathy (Bio14.6) and control hamsters (F1B). Then, 2D electrophoresis combined with MALDI-TOF/TOF tandem mass spectrometry detected 18 proteins with increased carbonyl level in cardiomyopathy hamsters compared with control hamster. Carbonyl modification of proteins related to ATP synthesis, including citric acid cycle and electron transport system, was observed in the hearts of hamsters with both types of cardiomyopathy. Further analysis indicated that left ventricular carbonyl production correlated negatively with succinyl-CoA:3-ketoacid-coenzyme A transferase 1 activity (r(2) = 0.60, P = 0.0007) and ATP concentration (r(2) = 0.29, P = 0.037), suggesting that protein carbonylation has negative effects on the levels of these biomolecules. Furthermore, carbonyl production significantly correlated with plasma Troponin T level (r(2) = 0.33, P = 0.026). Reduction of energy metabolism by oxidative damage may contribute to the development of left ventricular impairment in cardiomyopathy.
  • Masahiro Nakatochi, Sahoko Ichihara, Ken Yamamoto, Keiko Naruse, Shigeki Yokota, Hiroyuki Asano, Tatsuaki Matsubara, Mitsuhiro Yokota
    Clinical Epigenetics 9 (1) 54  1868-7083 2017/05 [Refereed][Not invited]
     
    Background: Development of cardiovascular disease (CVD), including coronary artery disease, arrhythmia, and ischemic stroke, depends on environmental and genetic factors. To investigate the epigenetic basis of myocardial infarction (MI), we performed an epigenome-wide association study for this condition in elderly Japanese subjects. A total of 192 case subjects with MI and 192 control subjects were recruited from hospital attendees and the general population, respectively. Genome-wide DNA methylation (DNAm) profiles for DNA isolated from whole blood were obtained by analysis with an Infinium HumanMethylation450 BeadChip. The relation of DNAm sites found to be significantly associated with MI to nearby single nucleotide polymorphisms (SNPs) previously shown to be associated with CVD was assessed in the control group. Findings: Three DNAm sites (cg06642177, cg07786668, cg17218495) showed genome-wide significant associations with MI (p = 4.33 × 10−8, 3.96 × 10−10, and 3.77 × 10−8, respectively). Two of these sites (cg07786668, cg17218495) still showed such associations after adjustment for classical risk factors of MI (p = 1.04 × 10−7 and 6.60 × 10−8, respectively). The DNAm sites cg07786668 and cg17218495 are located in ZFHX3 (zinc finger homeobox 3) and SMARCA4 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a, member 4) genes, respectively. SNPs in ZFHX3 or SMARCA4 that were previously found to be associated with CVD were not significantly associated with these DNAm sites in our control subjects. Conclusions: We identified two DNAm sites—cg07786668 in ZFHX3 and cg17218495 in SMARCA4— that are independently and significantly associated with MI. Our results suggest that the development of MI might be influenced by changes in DNAm at these sites via a pathway that differs from that affected by CVD-associated SNPs in these genes. The Kita-Nagoya Genomic Epidemiology (KING) study, which was the source of control samples in the present study, was registered in ClinicalTrials.gov (NCT00262691) on 6 December 2005.
  • Takaaki Morimoto, Yohei Mineharu, Koh Ono, Masahiro Nakatochi, Sahoko Ichihara, Risako Kabata, Yasushi Takagi, Yang Cao, Lanying Zhao, Hatasu Kobayashi, Kouji H. Harada, Katsunobu Takenaka, Takeshi Funaki, Mitsuhiro Yokota, Tatsuaki Matsubara, Ken Yamamoto, Hideo Izawa, Takeshi Kimura, Susumu Miyamoto, Akio Koizumi
    PLOS ONE 12 (4) e0175649  1932-6203 2017/04 [Refereed][Not invited]
     
    Background The genetic architecture of coronary artery disease has not been fully elucidated, especially in Asian countries. Moyamoya disease is a progressive cerebrovascular disease that is reported to be complicated by coronary artery disease. Because most Japanese patients with moyamoya disease carry the p.R4810K variant of the ring finger 213 gene (RNF213), this may also be a risk factor for coronary artery disease; however, this possibility has never been tested. Methods and results We genotyped the RNF213 p.R4810K variant in 956 coronary artery disease patients and 716 controls and tested the association between p.R4810K and coronary artery disease. We also validated the association in an independent population of 311 coronary artery disease patients and 494 controls. In the replication study, the p.R4810K genotypes were imputed from genome-wide genotyping data based on the 1000 Genomes Project. We used multivariate logistic regression analyses to adjust for well-known risk factors such as dyslipidemia and smoking habits. In the primary study population, the frequency of the minor variant allele was significantly higher in patients with coronary artery disease than in controls (2.04% vs. 0.98%), with an odds ratio of 2.11 (p = 0.017). Under a dominant model, after adjustment for risk factors, the association remained significant, with an odds ratio of 2.90 (95% confidence interval: 1.37-6.61; p = 0.005). In the replication study, the association was significant after adjustment for age and sex (odds ratio = 4.99; 95% confidence interval: 1.16-21.53; p = 0.031), although it did not reach statistical significance when further adjusted for risk factors (odds ratio = 3.82; 95% confidence interval: 0.87-16.77; p = 0.076). Conclusions The RNF213p.R4810K variant appears to be significantly associated with coronary artery disease in the Japanese population.
  • Fen Huang, Sahoko Ichihara, Yuki Yamada, Shameema Banu, Gaku Ichihara
    Journal of applied toxicology : JAT 37 (3) 331 - 338 0260-437X 2017/03 [Refereed][Not invited]
     
    The pathophysiology of hypertension is complex and multifactorial, and includes exposure to various chemical substances. Several recent studies have documented the reproductive and neurological toxicities of 1-bromopropane (1-BP). Given that 1-BP increased reactive oxygen species in the brain of rats, we hypothesized that 1-BP also has cardiovascular toxicity through increased oxidative stress. To test this hypothesis, male F344 and Wistar Nagoya rats (n = 7-8 per group per test) were exposed to 0 or 1000 ppm of 1-BP via inhalation for 4 weeks (8 h per day, 7 days per week). The exposure to 1-BP increased systolic blood pressure. This effect was associated with a significant decrease in the reduced/oxidized glutathione ratio. A significant increase in nitrotyrosine levels, activation of the NADPH oxidase pathway, which was evidenced by upregulation of gp91phox, a NADPH oxidase subunit, and significant decreases in the expressions of antioxidant molecules such as Cu/Zn- and Mn-superoxide dismutase catalase, and nuclear factor erythroid 2-related factor 2, were observed in the aortas of Wistar Nagoya rats exposed to 1-BP. Our results indicate that subacute (4-week) inhalation exposure to 1-BP increases blood pressure and suggest that this cardiovascular toxic effect is due, at least in part, to increased oxidative stress mediated through activation of the NADPH oxidase pathway. Further study is needed to assess whether NADPH oxidase activation causes the increase in blood pressure in the rats exposed to 1-BP. Copyright © 2016 John Wiley & Sons, Ltd.
  • Yuki Kitamura, Ryoko Usami, Sahoko Ichihara, Hirotaka Kida, Masayuki Satoh, Hidekazu Tomimoto, Mariko Murata, Shinji Oikawa
    NEUROLOGICAL RESEARCH 39 (3) 231 - 238 0161-6412 2017 [Refereed][Not invited]
     
    Objectives: Alzheimer's disease (AD) is the most common cause of dementia in elderly persons. Since the pathology of AD develops slowly from a preclinical or early phase into a fully expressed clinical syndrome, at the time of diagnosis the disease has been progressing for many years. To facilitate the early diagnosis of AD, we performed protein profiling of blood in patients with mild AD as defined by the Functional Assessment Staging (FAST) scale. Methods: Plasma samples from mild AD patients and healthy controls were analyzed using two-dimensional differential gel electrophoresis (2D-DIGE) combined with matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF/MS) followed by peptide mass fingerprinting. Results: Three downregulated proteins were identified: apolipoprotein A-1, alpha-2-HS-glycoprotein, and afamin. Two proteins, including apolipoprotein A-4 and fibrinogen gamma chain, were upregulated in mild AD patients. Discussion: Our results suggest that altered expression levels of these proteins in plasma may yield candidate biomarkers for the early diagnosis of AD.
  • Cai Zong, Xiao Zhang, Chinyen Huang, Jie Chang, C Edwin Garner, Toshihiro Sakurai, Masashi Kato, Sahoko Ichihara, Gaku Ichihara
    Toxicology research 5 (6) 1522 - 1529 2045-452X 2016/11 [Refereed][Not invited]
     
    1-Bromopropane (1BP) is widely used as an alternative to ozone-depleting solvents. The present study investigated the role of P450s in 1BP-induced male reproductive toxicity. Mice co-treated with 1-aminobenzotriazole (ABT), a non-selective P450 inhibitor, were exposed to 1BP at 0, 50, 250, or 1200 ppm, while saline-treated control mice were exposed to 1BP at 0, 50, or 250 ppm, for 4 weeks. In the saline-treated mice, exposure to 1BP at 250 ppm decreased the sperm count and sperm motility. Histopathological examination showed that exposure to 1BP at 50 and 250 ppm increased the number of elongated spermatids retained at the basal region of stage IX, X and XI seminiferous tubules, while exposure to 1BP at 250 ppm increased the number of periodic acid-Schiff (PAS)-positive round structures in stage IX, X, and XI seminiferous tubules. Co-treatment with ABT prevented the above changes induced by exposure to 1BP at 50 or 250 ppm. However, ABT-treated mice exposed to 1BP in the 1200 ppm group showed decreases in the weights of reproductive organs, epididymal sperm count and motility, increases in epididymal sperm with abnormal heads, retained spermatids and PAS-positive round structures in stages IX-XI, depletion of spermatogenic cells in part of the seminiferous tubules, and a small number of round spermatids in stage VII seminiferous tubules. The results at 50 and 250 ppm of 1-BP exposure indicate that P450s play important roles in 1BP-induced testicular toxicity. The control of P450 activity reduced 1BP-induced male reproductive toxicities including spermiation failure, reduction of epididymal sperm count and motility, and formation of PAS-positive round structures at postspermiation stages.
  • Yuka Suzuki, Saeko Tada-Oikawa, Yasuhiko Hayashi, Kiyora Izuoka, Misa Kataoka, Shunsuke Ichikawa, Wenting Wu, Cai Zong, Gaku Ichihara, Sahoko Ichihara
    Particle and fibre toxicology 13 (1) 54 - 54 2016/10 [Refereed][Not invited]
     
    BACKGROUND: The use of carbon nanotubes has increased lately. However, the cardiovascular effect of exposure to carbon nanotubes remains elusive. The present study investigated the effects of pulmonary exposure to single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) on atherosclerogenesis using normal human aortic endothelial cells (HAECs) and apolipoprotein E-deficient (ApoE-/-) mice, a model of human atherosclerosis. METHODS: HAECs were cultured and exposed to SWCNTs or DWCNTs for 16 h. ApoE-/- mice were exposed to SWCNTs or DWCNTs (10 or 40 μg/mouse) once every other week for 10 weeks by pharyngeal aspiration. RESULTS: Exposure to CNTs increased the expression level of adhesion molecule (ICAM-1) and enhanced THP-1 monocyte adhesion to HAECs. ApoE-/- mice exposed to CNTs showed increased plaque area in the aorta by oil red O staining and up-regulation of ICAM-1 expression in the aorta, compared with vehicle-treated ApoE-/- mice. Endothelial progenitor cells (EPCs) are mobilized from the bone marrow into the circulation and subsequently migrate to the site of endothelial damage and repair. Exposure of ApoE-/- mice to high-dose SWCNTs or DWCNTs reduced the colony-forming units of EPCs in the bone marrow and diminished their migration function. CONCLUSION: The results suggested that SWCNTs and DWCNTs enhanced atherosclerogenesis by promoting monocyte adhesion to endothelial cells and inducing EPC dysfunction.
  • Cai Zong, C Edwin Garner, Chinyen Huang, Xiao Zhang, Lingyi Zhang, Jie Chang, Shinya Toyokuni, Hidenori Ito, Masashi Kato, Toshihiro Sakurai, Sahoko Ichihara, Gaku Ichihara
    Toxicology letters 258 249 - 258 0378-4274 2016/09 [Refereed][Not invited]
     
    Neurotoxicity of 1-bromopropane (1-BP) has been reported in both human cases and animal studies. To date, neurotoxicity of 1-BP has been induced in rats but not in mice due to the lethal hepatotoxicity of 1-BP. Oxidization by cytochromes P450 and conjugation with glutathione (GSH) are two critical metabolism pathways of 1-BP and play important roles in toxicity of 1-BP. The aim of the present study was to establish a murine model of 1-BP neurotoxicity, by reducing the hepatotoxicity of 1-BP with 1-aminobenzotriazole (1-ABT); a commonly used nonspecific P450s inhibitor. The results showed that subcutaneous or intraperitoneal injection of 1-ABT at 50mg/kg body weight BID (100mg/kg BW/day) for 3days, inhibited about 92-96% of hepatic microsomal CYP2E1 activity, but only inhibited about 62-64% of CYP2E1 activity in brain microsomes. Mice treated with 1-ABT survived even after exposure to 1200ppm 1-BP for 4 weeks and histopathological studies showed that treatment with 1-ABT protected mice from 1-BP-induced hepatic necrosis, hepatocyte degeneration, and hemorrhage. After 4-week exposure to 1-BP, the brain weight of 1-ABT(+)/1200ppm 1-BP group was decreased significantly. In 1-ABT-treated groups, expression of hippocampal Ran protein and cerebral cortical GRP78 was dose-dependently increased by exposure to 1-BP. We conclude that the control of hepatic P450 activity allows the observation of effects of 1-BP on the murine brain at a higher concentration by reduction of hepatotoxicity. The study suggests that further experiments with liver-specific control of P450 activity using gene technology might provide better murine models for 1-bromopropane-induced neurotoxicity.
  • Saeko Tada-Oikawa, Gaku Ichihara, Hitomi Fukatsu, Yuka Shimanuki, Natsuki Tanaka, Eri Watanabe, Yuka Suzuki, Masahiko Murakami, Kiyora Izuoka, Jie Chang, Wenting Wu, Yoshiji Yamada, Sahoko Ichihara
    International journal of molecular sciences 17 (4) 576 - 576 2016/04 [Refereed][Not invited]
     
    Titanium dioxide (TiO₂) nanoparticles are widely used in cosmetics, sunscreens, biomedicine, and food products. When used as a food additive, TiO₂ nanoparticles are used in significant amounts as white food-coloring agents. However, the effects of TiO₂ nanoparticles on the gastrointestinal tract remain unclear. The present study was designed to determine the effects of five TiO₂ particles of different crystal structures and sizes in human epithelial colorectal adenocarcinoma (Caco-2) cells and THP-1 monocyte-derived macrophages. Twenty-four-hour exposure to anatase (primary particle size: 50 and 100 nm) and rutile (50 nm) TiO₂ particles reduced cellular viability in a dose-dependent manner in THP-1 macrophages, but in not Caco-2 cells. However, 72-h exposure of Caco-2 cells to anatase (50 nm) TiO₂ particles reduced cellular viability in a dose-dependent manner. The highest dose (50 µg/mL) of anatase (100 nm), rutile (50 nm), and P25 TiO₂ particles also reduced cellular viability in Caco-2 cells. The production of reactive oxygen species tended to increase in both types of cells, irrespective of the type of TiO₂ particle. Exposure of THP-1 macrophages to 50 µg/mL of anatase (50 nm) TiO₂ particles increased interleukin (IL)-1β expression level, and exposure of Caco-2 cells to 50 µg/mL of anatase (50 nm) TiO₂ particles also increased IL-8 expression. The results indicated that anatase TiO₂ nanoparticles induced inflammatory responses compared with other TiO₂ particles. Further studies are required to determine the in vivo relevance of these findings to avoid the hazards of ingested particles.
  • Masahiro Nakatochi, Sahoko Ichihara, Ken Yamamoto, Keizo Ohnaka, Yosuke Kato, Shigeki Yokota, Akihiro Hirashiki, Keiko Naruse, Hiroyuki Asano, Hideo Izawa, Tatsuaki Matsubara, Mitsuhiro Yokota
    DIABETOLOGIA 58 (12) 2781 - 2790 0012-186X 2015/12 [Refereed][Not invited]
     
    Aims/hypothesis To investigate epigenetic regulation of the plasma concentration of resistin, we performed an epigenome-wide association study for this variable and DNA methylation (DNAm) in an elderly Japanese cohort and then assessed the relation of single nucleotide polymorphisms (SNPs) associated with the plasma resistin concentration to DNAm level at identified sites. Methods The association of plasma resistin level with DNAm status was examined in 191 nondiabetic elderly men with the Illumina Infinium HumanMethylation450 BeadChip array. The association between DNAm status at specific sites in the flanking region of the resistin gene (RETN) and RETN mRNA abundance was then evaluated with a public data set for 1202 monocyte samples from a multi-ethnic cohort. Finally, the association of DNAm status and SNPs in the promoter region of RETN was assessed in two cohorts comprising a total of 478 Japanese individuals. Results DNAm status at cg02346997 located in the RETN promoter region showed a negative genome-wide significant association with the plasma resistin level (p = 6.02 x 10(-10)). Four DNAm sites in the RETN promoter region including cg02346997 (p = 4.23 x 10(-70)) showed a negative genome-wide significant association with RETN mRNA abundance in monocytes. Furthermore, the number of minor alleles of the RETN promoter SNPs rs34861192 and rs3219175 was negatively associated with DNAm level at cg02346997 (p = 4.43 x 10(-17)). Conclusions/interpretation Our results suggest that RETN promoter SNPs might influence the circulating resistin level through an effect on DNAm at cg02346997 and on RETN mRNA abundance in monocytes.
  • Norihiro Kato, Marie Loh, Fumihiko Takeuchi, Niek Verweij, Xu Wang, Weihua Zhang, Tanika N. Kelly, Danish Saleheen, Benjamin Lehne, Irene Mateo Leach, Alexander W. Drong, James Abbott, Simone Wahl, Sian-Tsung Tan, William R. Scott, Gianluca Campanella, Marc Chadeau-Hyam, Uzma Afzal, Tarunveer S. Ahluwalia, Marc Jan Bonder, Peng Chen, Abbas Dehghan, Todd L. Edwards, Tonu Esko, Min Jin Go, Sarah E. Harris, Jaana Hartiala, Silva Kasela, Anuradhani Kasturiratne, Chiea-Chuen Khor, Marcus E. Kleber, Huaixing Li, Zuan Yu Mok, Masahiro Nakatochi, Nur Sabrina Sapari, Richa Saxena, Alexandre F. R. Stewart, Lisette Stolk, Yasuharu Tabara, Ai Ling Teh, Ying Wu, Jer-Yuarn Wu, Yi Zhang, Imke Aits, Alexessander Da Silva Couto Alves, Shikta Das, Rajkumar Dorajoo, Jemma C. Hopewell, Yun Kyoung Kim, Robert W. Koivula, Jian'an Luan, Leo-Pekka Lyytikainen, Quang N. Nguyen, Mark A. Pereira, Iris Postmus, Olli T. Raitakari, Molly Scannell Bryan, Robert A. Scott, Rossella Sorice, Vinicius Tragante, Michela Traglia, Jon White, Ken Yamamoto, Yonghong Zhang, Linda S. Adair, Alauddin Ahmed, Koichi Akiyama, Rasheed Asif, Tin Aung, Ines Barroso, Andrew Bjonnes, Timothy R. Braun, Hui Cai, Li-Ching Chang, Chien-Hsiun Chen, Ching-Yu Cheng, Yap-Seng Chong, Rory Collins, Regina Courtney, Gail Davies, Graciela Delgado, Loi D. Do, Pieter A. Doevendans, Ron T. Gansevoort, Yu-Tang Gao, Tanja B. Grammer, Niels Grarup, Jagvir Grewal, Dongfeng Gu, Gurpreet S. Wander, Anna-Liisa Hartikainen, Stanley L. Hazen, Jing He, Chew-Kiat Heng, James E. Hixson, Albert Hofman, Chris Hsu, Wei Huang, Lise L. N. Husemoen, Joo-Yeon Hwang, Sahoko Ichihara, Michiya Igase, Masato Isono, Johanne M. Justesen, Tomohiro Katsuy, Muhammad G. Kibriya, Young Jin Kim, Miyako Kishimoto, Woon-Puay Koh, Katsuhiko Kohara, Meena Kumari, Kenneth Kwek, Nanette R. Lee, Jeannette Lee, Jiemin Liao, Wolfgang Lieb, David C. M. Liewald, Tatsuaki Matsubara, Yumi Matsushita, Thomas Meitinger, Evelin Mihailov, Lili Milani, Rebecca Mills, Nina Mononen, Martina Mueller-Nurasyid, Toru Nabika, Eitaro Nakashima, Hong Kiat Ng, Kjell Nikus, Teresa Nutile, Takayoshi Ohkubo, Keizo Ohnaka, Sarah Parish, Lavinia Paternoster, Hao Peng, Annette Peters, Son T. Pham, Mohitha J. Pinidiyapathirage, Mahfuzar Rahman, Hiromi Rakugi, Olov Rolandsson, Michelle Ann Rozario, Daniela Ruggiero, Cinzia F. Sala, Ralhan Sarju, Kazuro Shimokawa, Harold Snieder, Thomas Sparso, Wilko Spiering, John M. Starr, David J. Stott, Daniel O. Stram, Takao Sugiyama, Silke Szymczak, W. H. Wilson Tang, Lin Tong, Stella Trompet, Vaino Turjanmaa, Hirotsugu Ueshima, Andre G. Uitterlinden, Satoshi Umemura, Marja Vaarasmaki, Rob M. van Dam, Wiek H. van Gilst, Dirk J. van Veldhuisen, Jorma S. Viikari, Melanie Waldenberger, Yiqin Wang, Aili Wang, Rory Wilson, Tien-Yin Wong, Yong-Bing Xiang, Shuhei Yamaguchi, Xingwang Ye, Robin D. Young, Terri L. Young, Jian-Min Yuan, Xueya Zhou, Folkert W. Asselbergs, Marina Ciullo, Robert Clarke, Panos Deloukas, Andre Franke, Paul W. Franks, Steve Franks, Yechiel Friedlander, Myron D. Gross, Zhirong Guo, Torben Hansen, Marjo-Riitta Jarvelin, Torben Jorgensen, J. Wouter Jukema, Mika Kahonen, Hiroshi Kajio, Mika Kivimaki, Jong-Young Lee, Terho Lehtimaki, Allan Linneberg, Tetsuro Miki, Oluf Pedersen, Nilesh J. Samani, Thorkild I. A. Sorensen, Ryoichi Takayanagi, Daniela Toniolo, Habibul Ahsan, Hooman Allayee, Yuan-Tsong Chen, John Danesh, Ian J. Deary, Oscar H. Franco, Lude Franke, Bastiaan T. Heijman, Joanna D. Holbrook, Aaron Isaacs, Bong-Jo Kim, Xu Lin, Jianjun Liu, Winfried Maerz, Andres Metspalu, Karen L. Mohlke, Dharambir K. Sanghera, Xiao-Ou Shu, Joyce B. J. van Meurs, Eranga Vithana, Ananda R. Wickremasinghe, Cisca Wijmenga, Bruce H. W. Wolffenbuttel, Mitsuhiro Yokota, Wei Zheng, Dingliang Zhu, Paolo Vineis, Soterios A. Kyrtopoulos, Jos C. S. Kleinjans, Mark I. McCarthy, Richie Soong, Christian Gieger, James Scott, Yik-Ying Teo, Jiang He, Paul Elliott, E. Shyong Tai, Pim van der Harst, Jaspal S. Kooner, John C. Chambers
    NATURE GENETICS 47 (11) 1282 - + 1061-4036 2015/11 [Refereed][Not invited]
     
    We carried out a trans-ancestry genome-wide association and replication study of blood pressure phenotypes among up to 320,251 individuals of East Asian, European and South Asian ancestry. We find genetic variants at 12 new loci to be associated with blood pressure (P = 3.9 x 10(-11) to 5.0 x 10(-21)). The sentinel blood pressure SNPs are enriched for association with DNA methylation at multiple nearby CpG sites, suggesting that, at some of the loci identified, DNA methylation may lie on the regulatory pathway linking sequence variation to blood pressure. The sentinel SNPs at the 12 new loci point to genes involved in vascular smooth muscle (IGFBP3, KCNK3, PDE3A and PRDM6) and renal (ARHGAP24, OSR1, SLC22A7 and TBX2) function. The new and known genetic variants predict increased left ventricular mass, circulating levels of NT-proBNP, and cardiovascular and all-cause mortality (P = 0.04 to 8.6 x 10(-6)). Our results provide new evidence for the role of DNA methylation in blood pressure regulation.
  • Jie Chang, Gaku Ichihara, Yasuhito Shimada, Saeko Tada-Oikawa, Junya Kuroyanagi, Beibei Zhang, Yuka Suzuki, Radwa Sehsah, Masashi Kato, Toshio Tanaka, Sahoko Ichihara
    Journal of nanoscience and nanotechnology 15 (3) 2140 - 7 1533-4880 2015/03 [Refereed][Not invited]
     
    The present study investigated the effects of exposure to metal oxide nanoparticles on vasculogenesis/angiogenesis using transgenic zebrafish. The study also examined the potential mechanisms involved in those effects using human umbilical vein endothelial cells (HUVEC). TG (nacre/fli1:EGFP) zebrafish were exposed to nano-sized titanium dioxide (TiO2), silica dioxide (SiO2), and copper oxide (CuO) particles at 0.01, 1 and 100 µg/ml concentrations from 1 to 5 dpf (day-post-fertilization). Angiogenesis was evaluated morphologically at the end of exposure. Exposure to CuO nanoparticles reduced the number of transversely-running subintestinal vessels in TG zebrafish. Exposure to CuO nanoparticles down-regulated the expression of vascular endothelial growth factor (VEGF) and VEGF receptor in endothelial cells sorted by Fluorescence Activated Cell Sorter (FACS). Exposure of HUVEC to CuO nanoparticles reduced cell viability and increased apoptotic index in a dose-dependent manner. The results suggested that CuO nanoparticles inhibit vasculogenesis through reduction of VEGF expression and induction of apoptosis.
  • Zhenlie Huang, Sahoko Ichihara, Shinji Oikawa, Jie Chang, Lingyi Zhang, Shijie Hu, Hanlin Huang, Gaku Ichihara
    Toxicology and applied pharmacology 282 (2) 151 - 60 0041-008X 2015/01 [Refereed][Not invited]
     
    1-Bromopropane (1-BP) is neurotoxic in both experimental animals and human. To identify phosphorylated modification on the unrecognized post-translational modifications of proteins and investigate their role in 1-BP-induced neurotoxicity, changes in hippocampal phosphoprotein expression levels were analyzed quantitatively in male F344 rats exposed to 1-BP inhalation at 0, 400, or 1000 ppm for 8 h/day for 1 or 4 weeks. Hippocampal protein extracts were analyzed qualitatively and quantitatively by Pro-Q Diamond gel staining and SYPRO Ruby staining coupled with two-dimensional difference in gel electrophoresis (2D-DIGE), respectively, as well as by matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) to identify phosphoproteins. Changes in selected proteins were further confirmed by Manganese II (Mn(2+))-Phos-tag SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Bax and cytochrome c protein levels were determined by western blotting. Pro-Q Diamond gel staining combined with 2D-DIGE identified 26 phosphoprotein spots (p<0.05), and MALDI-TOF/MS identified 18 up-regulated proteins and 8 down-regulated proteins. These proteins are involved in the biological process of response to stimuli, metabolic processes, and apoptosis signaling. Changes in the expression of phosphorylated 14-3-3 θ were further confirmed by Mn(2+)-Phos-tag SDS-PAGE. Western blotting showed overexpression of Bax protein in the mitochondria with down-regulation in the cytoplasm, whereas cytochrome c expression was high in the cytoplasm but low in the mitochondria after 1-BP exposure. Our results suggest that the pathogenesis of 1-BP-induced hippocampal damage involves inhibition of antiapoptosis process. Phosphoproteins identified in this study can potentially serve as biomarkers for 1-BP-induced neurotoxicity.
  • Ichihara S
    Nihon eiseigaku zasshi. Japanese journal of hygiene 70 (1) 97  0021-5082 2015 [Refereed][Not invited]
  • Saeko Tada-Oikawa, Gaku Ichihara, Yuka Suzuki, Kiyora Izuoka, Wenting Wu, Yoshiji Yamada, Takashi Mishima, Sahoko Ichihara
    Toxicology reports 2 692 - 701 2015 [Refereed][Not invited]
     
    Zinc oxide (ZnO) nanoparticles have been widely used in industry, cosmetics, and biomedicine. Recent studies suggested that these nanoparticles could have a major impact on the cardiovascular system. Endothelial progenitor cells (EPCs) contribute to postnatal endothelial repair and regeneration. The present study dissected the effects of ZnO nanoparticles on vasculogenesis using human endothelial colony forming cells (ECFCs), which participate in post-natal vasculogenesis. Two types of ZnO particles were used (nano and micro), in addition to zinc chloride solutions with zinc ion concentrations equal to those in ZnO nanoparticles. Twenty-four-hour exposure induced cytotoxicity in a dose-dependent manner and increased ECFCs apoptosis in all groups. The exposure also reduced the functional capacity of ECFCs on Matrix gel to form tubules, compared with the control cells. These effects were associated with downregulation of expression of vascular endothelial growth factor receptor, VEGFR2 and CXC chemokine receptor, CXCR4. The results suggest that ZnO nanoparticles suppress vasculogenesis from ECFCs through downregulation of the expression of receptors related to vasculogenesis. These effects are based the concentration of released Zn(II).
  • Lingyi Zhang, Cai Zong, Sahoko Ichihara, Hisao Naito, Shinya Toyokuni, Shinji Kumagai, Gaku Ichihara
    Journal of occupational health 57 (6) 548 - 54 1341-9145 2015 [Refereed][Not invited]
     
    OBJECTIVES: It has been reported that 1,2-Dichloropropane (DCP) induced cholangiocarcinoma (CCA) in offset color proof-printing workers. However, exposure to DCP by inhalation or gavage for 2 year did not induce CCA in mice and rats. The present study mapped the hepatic distribution of GST, which is known to activate dihalogenated alkanes, and proliferative and fibrotic changes in bile ducts in various species to find the most appropriate animal model of DCP-induced CCA. METHODS: First, 12 each of C57BL/6J mice, Balb/cA mice, F344 rats, Syrian hamsters, and guinea pigs were divided into four equal groups and exposed to DCP at 0, 300, 1,000, or 3,000 ppm 8 hours/day for 7 days. Second, 32 Balb/cA mice and 32 Syrian hamsters were each divided into four equal groups and exposed to DCP at 0, 200, 400, and 800 ppm 6 hours/day for 14 days. After the last exposure, the animals were decapitated, and the livers were dissected out for histopathological evaluation. Immunostaining was conducted to determine the distribution of GSTT1, GSTM1, and GSTPi, as well as the expression of proliferation marker Ki67. RESULTS: GSTT1, GSTM1, and GSTPi were expressed in both hepatocytes and bile duct cells in all control and exposed animals. There was no clear difference in the expression of Ki67 between the exposed groups and the control. No fibrotic changes were observed in any species or strains examined. CONCLUSIONS: Expression of GSTT1 or other GST isozymes might not explain the difference in sensitivity of hepatocytes and the bile duct to DCP between humans and rodents.
  • Wenting Wu, Gaku Ichihara, Naozumi Hashimoto, Yoshinori Hasegawa, Yasuhiko Hayashi, Saeko Tada-Oikawa, Yuka Suzuki, Jie Chang, Masashi Kato, Corina N D'Alessandro-Gabazza, Esteban C Gabazza, Sahoko Ichihara
    International journal of molecular sciences 16 (1) 660 - 76 2014/12 [Refereed][Not invited]
     
    Zinc oxide (ZnO) nanoparticles are widely used in various products, and the safety evaluation of this manufactured material is important. The present study investigated the inflammatory and fibrotic effects of pulmonary exposure to ZnO nanoparticles in a mouse model of pulmonary fibrosis. Pulmonary fibrosis was induced by constant subcutaneous infusion of bleomycin (BLM). Female C57BL/6Jcl mice were divided into BLM-treated and non-treated groups. In each treatment group, 0, 10, 20 or 30 µg of ZnO nanoparticles were delivered into the lungs through pharyngeal aspiration. Bronchoalveolar lavage fluid (BALF) and the lungs were sampled at Day 10 or 14 after administration. Pulmonary exposure by a single bolus of ZnO nanoparticles resulted in severe, but transient inflammatory infiltration and thickening of the alveolar septa in the lungs, along with the increase of total and differential cell counts in BLAF. The BALF level of interleukin (IL)-1β and transforming growth factor (TGF)-β was increased at Day 10 and 14, respectively. At Day 10, the synergistic effect of BLM and ZnO exposure was detected on IL-1β and monocyte chemotactic protein (MCP)-1 in BALF. The present study demonstrated the synergistic effect of pulmonary exposure to ZnO nanoparticles and subcutaneous infusion of BLM on the secretion of pro-fibrotic cytokines in the lungs.
  • Yuka Suzuki, Saeko Tada-Oikawa, Gaku Ichihara, Masayuki Yabata, Kiyora Izuoka, Masako Suzuki, Kiyoshi Sakai, Sahoko Ichihara
    Toxicology and applied pharmacology 278 (1) 16 - 25 0041-008X 2014/07 [Refereed][Not invited]
     
    Metal oxide nanoparticles are widely used in industry, cosmetics, and biomedicine. However, the effects of exposure to these nanoparticles on the cardiovascular system remain unknown. The present study investigated the effects of nanosized TiO2 and ZnO particles on the migration and adhesion of monocytes, which are essential processes in atherosclerogenesis, using an in vitro set-up of human umbilical vein endothelial cells (HUVECs) and human monocytic leukemia cells (THP-1). We also examined the effects of exposure to nanosized metal oxide particles on macrophage cholesterol uptake and foam cell formation. The 16-hour exposure to ZnO particles increased the level of monocyte chemotactic protein-1 (MCP-1) and induced the migration of THP-1 monocyte mediated by increased MCP-1. Exposure to ZnO particles also induced adhesion of THP-1 cells to HUVECs. Moreover, exposure to ZnO particles, but not TiO2 particles, upregulated the expression of membrane scavenger receptors of modified LDL and increased cholesterol uptake in THP-1 monocytes/macrophages. In the present study, we found that exposure to ZnO particles increased macrophage cholesterol uptake, which was mediated by an upregulation of membrane scavenger receptors of modified LDL. These results suggest that nanosized ZnO particles could potentially enhance atherosclerogenesis and accelerate foam cell formation.
  • Ichiro Yajima, Machiko Iida, Mayuko Y. Kumasaka, Yasuhiro Omata, Nobutaka Ohgami, Jie Chang, Sahoko Ichihara, Masaru Hori, Masashi Kato
    EXPERIMENTAL DERMATOLOGY 23 (6) 424 - 425 0906-6705 2014/06 [Refereed][Not invited]
     
    The incidence of cutaneous malignant melanoma is increasing at a greater rate than that of any other cancer in the world. However, an effective therapy for malignant melanoma has not been established. Recently, some studies have shown an antitumor effect of non-equilibrium atmospheric pressure plasmas (NEAPPs) in vitro. Here, we examined the in vivo effect of NEAPP on cell cycle regulators, key elements for malignant transformation, in spontaneously developed benign melanocytic tumors in a hairless animal model. NEAPP irradiation decreased expression levels of cell cycle promoters, Cyclin D1, E1 and E2, and increased expression level of a cell cycle repressor, p27KIP1. Cyclin D1, E1 and E2 and p27KIP expression levels were associated with malignant transformation of the benign tumor in the animal model. Our results suggest that NEAPP irradiation suppresses malignant transformation of a benign melanocytic tumor via control of the expression levels of cell cycle regulators.
  • Machiko Iida, Ichiro Yajima, Nobutaka Ohgami, Haruka Tamura, Kozue Takeda, Sahoko Ichihara, Masaru Hori, Masashi Kato
    EUROPEAN JOURNAL OF DERMATOLOGY 24 (3) 392 - 394 1167-1122 2014/05 [Refereed][Not invited]
  • Hideki Horibe, Chikara Ueyama, Tetsuo Fujimaki, Mitsutoshi Oguri, Kimihiko Kato, Sahoko Ichihara, Yoshiji Yamada
    MOLECULAR MEDICINE REPORTS 9 (3) 808 - 812 1791-2997 2014/03 [Refereed][Not invited]
     
    We have previously shown that the CT polymorphism (rs6929846) of the butyrophilin, subfamily 2, member A1 gene (BTN2A1) was significantly associated with myocardial infarction. Considering that dyslipidemia is a significant risk factor for coronary heart disease, it was hypothesized that the association between rs6929846 of BTN2A1 and myocardial infarction may be attributable, at least in part, to its effect on the susceptibility to dyslipidemia. The purpose of the present study was to examine a possible association of rs6929846 of BTN2A1 with dyslipidemia in community-dwelling individuals. The study subjects were comprised of 5,958 community-dwelling individuals (2,909 subjects with dyslipidemia and 3,049 controls) who were recruited into a population-based cohort study in Inabe, Japan. Dyslipidemia was defined by a serum concentration of triglycerides of 1.65 mmol/l, a serum high-density lipoprotein-cholesterol concentration of <1.04 mmol/l or a serum low-density lipoprotein (LDL)-cholesterol concentration of 3.64 mmol/l. A comparison of the allele frequencies or genotype distributions by the (2) test revealed that rs6929846 of BTN2A1 was significantly associated with dyslipidemia (P<0.05). A multivariable logistic regression analysis adjusted for age, gender, body mass index, smoking status and the prevalence of diabetes mellitus revealed that rs6929846 of BTN2A1 was significantly (dominant model; P=2.4x10(-4); odds ratio, 1.29) associated with dyslipidemia, with the minor T allele representing a risk for this condition. Among all the individuals, the serum concentrations of total cholesterol, triglycerides and LDL-cholesterol were significantly greater for individuals in the combined CT and TT genotype groups than for those with the CC genotype. BTN2A1 may thus be a susceptibility gene for dyslipidemia in community-dwelling individuals.
  • Ying Wu, He Gao, Huaixing Li, Yasuharu Tabara, Masahiro Nakatochi, Yen-Feng Chiu, Eun Jung Park, Wanqing Wen, Linda S. Adair, Judith B. Borja, Qiuyin Cai, Yi-Cheng Chang, Peng Chen, Damien C. Croteau-Chonka, Marie P. Fogarty, Wei Gan, Chih-Tsueng He, Chao A. Hsiung, Chii-Min Hwu, Sahoko Ichihara, Michiya Igase, Jaeseong Jo, Norihiro Kato, Ryuichi Kawamoto, Christophor W. Kuzawa, Jeannette J. M. Lee, Jianjun Liu, Ling Lu, Thomas W. Mcdade, Haruhiko Osawa, Wayne H-H. Sheu, Yvonne Teo, Swarooparani Vadlamudi, Rob M. Van Dam, Yiqin Wang, Yong-Bing Xiang, Ken Yamamoto, Xingwang Ye, Terri L. Young, Wei Zheng, Jingwen Zhu, Xiao-Ou Shu, Chol Shin, Sun Ha Jee, Lee-Ming Chuang, Tetsuro Miki, Mitsuhiro Yokota, Xu Lin, Karen L. Mohlke, E. Shyong Tai
    HUMAN MOLECULAR GENETICS 23 (4) 1108 - 1119 0964-6906 2014/02 [Refereed][Not invited]
     
    Blood levels of adiponectin, an adipocyte-secreted protein correlated with metabolic and cardiovascular risks, are highly heritable. Genome-wide association (GWA) studies for adiponectin levels have identified 14 loci harboring variants associated with blood levels of adiponectin. To identify novel adiponectin-associated loci, particularly those of importance in East Asians, we conducted a meta-analysis of GWA studies for adiponectin in 7827 individuals, followed by two stages of replications in 4298 and 5954 additional individuals. We identified a novel adiponectin-associated locus on chromosome 10 near WDR11-FGFR2 (P 3.0 10(14)) and provided suggestive evidence for a locus on chromosome 12 near OR8S1-LALBA (P 1.2 10(7)). Of the adiponectin-associated loci previously described, we confirmed the association at CDH13 (P 6.8 10(165)), ADIPOQ (P 1.8 10(22)), PEPD (P 3.6 10(12)), CMIP (P 2.1 10(10)), ZNF664 (P 2.3 10(7)) and GPR109A (P 7.4 10(6)). Conditional analysis at ADIPOQ revealed a second signal with suggestive evidence of association only after conditioning on the lead SNP (P-initial 0.020; P-conditional 7.0 10(7)). We further confirmed the independence of two pairs of closely located loci (2 Mb) on chromosome 16 at CMIP and CDH13, and on chromosome 12 at GPR109A and ZNF664. In addition, the newly identified signal near WDR11-FGFR2 exhibited evidence of association with triglycerides (P 3.3 10(4)), high density lipoprotein cholesterol (HDL-C, P 4.9 10(4)) and body mass index (BMI)-adjusted waisthip ratio (P 9.8 10(3)). These findings improve our knowledge of the genetic basis of adiponectin variation, demonstrate the shared allelic architecture for adiponectin with lipids and central obesity and motivate further studies of underlying mechanisms.
  • Jie Chang, Shinji Oikawa, Hitoshi Iwahashi, Emiko Kitagawa, Ichiro Takeuchi, Masao Yuda, Chieko Aoki, Yoshiji Yamada, Gaku Ichihara, Masashi Kato, Sahoko Ichihara
    Diabetology & metabolic syndrome 6 (1) 8 - 8 2014/01 [Refereed][Not invited]
     
    BACKGROUND: The etiology of the metabolic syndrome is complex, and is determined by the interplay of both genetic and environmental factors. The present study was designed to identify genes and proteins in the adipose tissues with altered expression in the spontaneously hypertensive/NIH -corpulent rat, SHR/NDmcr-cp (CP) and to find possible molecular targets associated with the pathogenesis or progression of obesity related to the metabolic syndrome. METHODS: We extracted RNAs and proteins from the epididymal adipose tissues in CP, SHR/Lean (Lean), and Wistar Kyoto (WKY) rats and performed microarray analysis and two-dimensional difference in gel electrophoresis (2D-DIGE) linked to a matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS). RESULTS: The results showed different mRNA and protein expression levels in the adipose tissue: oligo DNA microarray identified 33 genes that were significantly (P < 0.01) up-regulated and 17 genes significantly down-regulated in CP compared with WKY and Lean rats at both 6 and 25 weeks of age. The affected genes-proteins were associated with lipolytic enzymes stimulated by peroxisome proliferator-activated receptor (PPAR) signaling. Further analysis using the 2D-DIGE connected with MALDI-TOF/TOF analysis, the expression of monoglyceride lipase (MGLL) was significantly up-regulated and that of carboxylesterase 3 (CES3) was significantly down-regulated in 6- and 25-week-old CP compared with age-matched control (WKY and Lean rats). CONCLUSIONS: Our results suggest the possible involvement of proteins associated with adipocyte lipolysis in obesity related to the metabolic syndrome.
  • Yuka Suzuki, Shingo Mitsushima, Ai Kato, Takanori Yamaguchi, Sahoko Ichihara
    CARDIOVASCULAR PATHOLOGY 23 (1) 43 - 49 1054-8807 2014/01 [Refereed][Not invited]
     
    Background: Cardiac dysfunction is reported in patients with the metabolic syndrome. We assessed the effects of high-phosphorus and zinc-free diet on cardiovascular system in spontaneously hypertensive rats (SHR)/NDmcr-cp (SHR/cp), a rat model of the metabolic syndrome. We also investigated the effects of N-acetyl-L-cysteine (NAC), an antioxidant, on the development of cardiac dysfunction under such conditions. Methods: Male SHR/cp and control [Wistar Kyoto (WKY)] rats were divided into three groups and fed control diet (P 0.3% w/w, Zn 0.2% w/w) or high-phosphorus and zinc-free (P 1.2% w/w, Zn 0.0% w/w) diet. The latter group was treated with either NAC (1.5 mg/g per day) or vehicle from 6 to 18 weeks of age (n=6 or 8 for each group). Results: High-phosphate and zinc-free diet increased systolic blood pressure in both WKY and SHR/cp. Echocardiography showed that high-phosphate and zinc-free diet markedly reduced left ventricular systolic and diastolic function in SHR/cp. Histopathologically, the same diet induced severe myocardial fibrosis in SHR/cp, and this effect was prevented by NAC. Whereas treatment with NAC prevented diastolic dysfunction induced by the same diet in WKY, it only improved systolic function but not diastolic function in SHR/cp. Conclusions: High-phosphate and zinc-free diet induced hypertension and cardiac dysfunction. These changes hamper the protective effects of NAC in the metabolic syndrome. Summary: The present study showed that consumption of high-phosphorus and zinc-free diet increased the myocardial expression of connective tissue growth factor and reduced the expression of metallothionein, which enhanced the development of severe cardiac dysfunction in rats with the metabolic syndrome. The results suggest that the metabolic syndrome seems to aggravate cardiac dysfunction and hamper the protective effects of antioxidant, NAC. (C) 2014 Published by Elsevier Inc.
  • Wenting Wu, Gaku Ichihara, Yuka Suzuki, Kiyora Izuoka, Saeko Oikawa-Tada, Jie Chang, Kiyoshi Sakai, Kunichi Miyazawa, Dale Porter, Vincent Castranova, Masami Kawaguchi, Sahoko Ichihara
    Industrial health 52 (1) 54 - 65 0019-8366 2014 [Refereed][Not invited]
     
    Nanomaterials tend to agglomerate in aqueous media, resulting in inaccurate safety assessment of the biological response to these substances. The present study searched for suitable dispersion methods for the preparation of nanomaterial suspensions. Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles were dispersed in a biocompatible dispersion medium by direct probe-type sonicator and indirect cup-type sonicator. Size characterization was completed using dynamic light scattering and transmission electron microscopy. A series of dispersion time and output power, as well as two different particle concentrations were tested. Microscopic contamination of metal titanium that broke away from the tip of the probe into the suspension was found. Size of agglomerated nanoparticles decreased with increase in sonication time or output power. Particle concentration did not show obvious effect on size distribution of TiO2 nanoparticles, while significant reduction of secondary diameter of ZnO was observed at higher concentration. A practicable protocol was then adopted and sizes of well-dispersed nanoparticles increased by less than 10% at 7 d after sonication. Multi-walled carbon nanotubes were also well dispersed by the same protocol. The cup-type sonicator might be a useful alternative to the traditional bath-type sonicator or probe-type sonicator based on its effective energy delivery and assurance of suspension purity.
  • Sahoko Ichihara, Ken Yamamoto, Hiroyuki Asano, Masahiro Nakatochi, Mayo Sukegawa, Gaku Ichihara, Hideo Izawa, Akihiro Hirashiki, Fumimaro Takatsu, Hisashi Umeda, Mitsunori Iwase, Haruo Inagaki, Haruo Hirayama, Takahito Sone, Kazuhiko Nishigaki, Shinya Minatoguchi, Myeong-Chan Cho, Yangsoo Jang, Hyo-Soo Kim, Jeong E Park, Saeko Tada-Oikawa, Hidetoshi Kitajima, Tatsuaki Matsubara, Kenji Sunagawa, Hiroaki Shimokawa, Akinori Kimura, Jong-Young Lee, Toyoaki Murohara, Ituro Inoue, Mitsuhiro Yokota
    Circulation. Cardiovascular genetics 6 (6) 569 - 78 1942-325X 2013/12 [Refereed][Not invited]
     
    BACKGROUND: Myocardial infarction (MI) is a leading cause of death worldwide. Given that a family history is an independent risk factor for coronary artery disease, genetic variants are thought to contribute directly to the development of this condition. The identification of susceptibility genes for coronary artery disease or MI may thus help to identify high-risk individuals and offer the opportunity for disease prevention. METHODS AND RESULTS: We designed a 5-step protocol, consisting of a genome-wide linkage study followed by association analysis, to identify novel genetic variants that confer susceptibility to coronary artery disease or MI. A genome-wide affected sib-pair linkage study with 221 Japanese families with coronary artery disease yielded a statistically significant logarithm of the odds score of 3.44 for chromosome 2p13 and MI. Further association analysis implicated Alström syndrome 1 gene (ALMS1) as a candidate gene within the linkage region. Validation association analysis revealed that representative single-nucleotide polymorphisms of the ALMS1 promoter region were significantly associated with early-onset MI in both Japanese and Korean populations. Moreover, direct sequencing of the ALMS1 coding region identified a glutamic acid repeat polymorphism in exon 1, which was subsequently found to be associated with early-onset MI. CONCLUSIONS: The glutamic acid repeat polymorphism of ALMS1 identified in the present study may provide insight into the pathogenesis of early-onset MI.
  • Yuka Suzuki, Gaku Ichihara, Sheik Mohideen Sahabudeen, Ai Kato, Takanori Yamaguchi, Kyoko Imanaka-Yoshida, Toshimichi Yoshida, Yoshiji Yamada, Sahoko Ichihara
    Experimental and toxicologic pathology : official journal of the Gesellschaft fur Toxikologische Pathologie 65 (7-8) 1173 - 82 0940-2993 2013/11 [Refereed][Not invited]
     
    Consumption of relatively high amounts of processed food can result in abnormal nutritional status, such as zinc deficiency or phosphorus excess. Moreover, hyperphosphatemia and hypozincemia are found in some patients with diabetic nephropathy and metabolic syndrome. The present study investigated the effects of high-phosphorus/zinc-free diet on the reproductive function of spontaneously hypertensive rats/NDmcr-cp (SHR/cp), a model of the metabolic syndrome. We also investigated the effects of antioxidant, N-acetyl-l-cysteine (NAC), on testicular dysfunction under such conditions. Male SHR/cp and control rats (Wistar Kyoto rats, WKY) were divided into three groups; rats fed control diet (P 0.3%, w/w; Zn 0.2%, w/w), high-phosphorus and zinc-deficient diet (P 1.2%, w/w; Zn 0.0%, w/w) with vehicle, or high-phosphorus and zinc-deficient diet with NAC (1.5mg/g/day) for 12 weeks (n=6 or 8 rats/group). The weights of testis and epididymis were significantly reduced by high-phosphate/zinc-free diet in both SHR/cp and WKY. The same diet significantly reduced caudal epididymal sperm count and motility and induced histopathological changes in the testis in both strains. Treatment with NAC provided significant protection against the toxic effects of the diet on testicular function in WKY, but not in SHR/cp. The lack of the protective effects of NAC on impaired spermatogenesis in SHR/cp could be due to the more pronounced state of oxidative stress observed in these rats compared with WKY.
  • Oguri M, Fujimaki T, Horibe H, Kato K, Ichihara S, Yamada Y
    Biomedical reports 1 (6) 868 - 872 2049-9434 2013/11 [Refereed][Not invited]
  • Takanori Yamaguchi, Kazuya Kitamori, Gaku Ichihara, Yuka Suzuki, Miyuki Ochiai, Yoshiji Yamada, Saeko Tada-Oikawa, Satoru Tsuchikura, Yukio Yamori, Sahoko Ichihara
    Clinical and experimental pharmacology & physiology 40 (7) 443 - 8 0305-1870 2013/07 [Refereed][Not invited]
     
    Obesity is associated with high chronic cardiac workload due to the need to supply more blood to peripheral tissue, and frequently leads to left ventricular (LV) dysfunction. The present study examined serial changes in cardiac function in the SHR/NDmcr-cp (SHR/cp) strain, an experimental model of obesity plus hypertension and metabolic syndrome. Transthoracic echocardiography was used to define cardiac dimensions and function in male spontaneously hypertensive rats (SHR/lean), SHR/cp and Wistar-Kyoto rats. We also assessed age-related changes in plasma and LV adipocytokine levels in this model. Although there were no significant differences in LV end-diastolic diameter and end-systolic diameter among the three rat strains until 24 weeks of age, these parameters were significantly higher and LV fractional shortening (%FS) was significantly lower in SHR/cp compared with SHR/lean at 32 weeks of age. At the same age, pronounced interstitial fibrosis and infiltration of macrophages and T lymphocytes into the LV was noted in SHR/cp relative to the other strains. In the myocardium, adiponectin levels were significantly lower and resistin levels and the expression of proinflammatory cytokines (tumour necrosis factor-α and interleukin-6) were significantly higher in SHR/cp than SHR/lean at 32 weeks of age. Using echocardiography, we demonstrated reduced systolic function in 32-week-old SHR/cp. Changes in myocardial cytokine concentrations could be involved in worsening of cardiac function in our animal model of metabolic syndrome.
  • Yoshiji Yamada, Tamotsu Nishida, Sahoko Ichihara, Kimihiko Kato, Tetsuo Fujimaki, Mitsutoshi Oguri, Hideki Horibe, Tetsuro Yoshida, Sachiro Watanabe, Kei Satoh, Yukitoshi Aoyagi, Michio Fukuda, Motoji Sawabe
    JOURNAL OF MEDICAL GENETICS 50 (6) 410 - 418 0022-2593 2013/06 [Refereed][Not invited]
     
    Background Although genome-wide association studies (GWASs) have implicated several genes in the predisposition to chronic kidney disease (CKD) in Caucasian or African American populations, the genes that confer susceptibility to CKD in Asian populations remain to be identified definitively. We performed a GWAS to identify genetic variants that confer susceptibility to CKD in Japanese individuals. Methods 3851 Japanese individuals from three independent subject panels were examined. Subject panels A, B, and C comprised 252, 910, and 190 individuals with CKD and 249, 838, and 1412 controls, respectively. A GWAS for CKD was performed in subject panel A. Results Five single nucleotide polymorphisms (SNPs) at chromosome 3q28, ALPK1, FAM78B, and UMODL1 were significantly (false discovery rate<0.05) associated with CKD by the GWAS. The relation of these five SNPs and of an additional 22 SNPs at these loci to CKD was examined in subject panel B, revealing that rs9846911 at 3q28 was significantly associated with CKD in all individuals and that rs2074381 and rs2074380 in ALPK1 were associated with CKD in individuals with diabetes mellitus. These three SNPs were further examined in subject panel C, revealing that rs2074381 and rs2074380 were significantly associated with CKD. For subject panels B and C combined, rs9846911 was significantly associated with CKD in all individuals and rs2074381 and rs2074380 were associated with CKD in diabetic individuals. Conclusions Chromosome 3q28 may be a susceptibility locus for CKD in Japanese individuals, and ALPK1 may be a susceptibility gene for CKD in such individuals with diabetes mellitus.
  • Sahoko Ichihara
    ENVIRONMENTAL HEALTH AND PREVENTIVE MEDICINE 18 (3) 177 - 184 1342-078X 2013/05 [Refereed][Not invited]
     
    Oxidative stress and inflammation are implicated in cardiovascular diseases such as atherosclerosis, reperfusion injury, hypertension, and heart failure. High levels of oxidative stress resulting from increased cardiac generation of reactive oxygen species (ROS) is thought to contribute to contractile and endothelial dysfunction, apoptosis and necrosis of myocytes, and extracellular matrix remodeling in the heart. ROS activate several transcription factors known as redox-regulated transcription factors, and these transcription factors play important roles in the pathophysiology of cardiovascular diseases. This review focuses on the pathological roles of environmental and redox stresses in cardiovascular diseases, especially severe cardiac dysfunction and the transition from compensated hypertrophy to heart failure. The aryl hydrocarbon receptor (AHR) and NF-E2 p45-related factor (Nrf2) are transcription factors involved in the regulation of drug-metabolizing enzymes. AHR has been studied as a receptor for environmental contaminants and as a mediator of chemical toxicity. However, other roles for AHR in cardiac and vascular development have recently been described. Moreover, Nrf2 protects against oxidative stress by increasing the transcription of genes, including those for several antioxidant enzymes. The roles of these transcription factors, AHR and Nrf2 in angiogenesis are also discussed in this review.
  • Lingyi Zhang, Taku Nagai, Kiyofumi Yamada, Daisuke Ibi, Sahoko Ichihara, Kaviarasan Subramanian, Zhenlie Huang, Sahabudeen Sheik Mohideen, Hisao Naito, Gaku Ichihara
    Toxicology 304 76 - 82 0300-483X 2013/02 [Refereed][Not invited]
     
    PURPOSE: 1-Bromopropane (1-BP) intoxication is associated with depression and cognitive and memory deficits. The present study tested the hypothesis that 1-BP suppresses neurogenesis in the dentate gyrus, which is involved in higher cerebral function, in adult rats. METHODS: Four groups of 12 male Wistar rats were exposed to 0, 400, 800, 1000 ppm 1-BP, 8 h/day for 7 days. Another four groups of six rats each were exposed to 0, 400, 800 and 1000 ppm 1-BP for 2 weeks followed by 0, 200, 400 and 800 ppm for another 2 weeks, respectively. Another four groups of six rats each were exposed to 0, 200, 400 and 800 ppm 1-BP for 4 weeks. Rats were injected with 5-bromo-2'-deoxy-uridine (BrdU) after 4-week exposure at 1000/800 ppm to examine neurogenesis in the dentate gyrus by immunostaining. We measured factors known to affect neurogenesis, including monoamine levels, and mRNA expression levels of brain-derived neurotrophic factor (BDNF) and glucocorticoid receptor (GR), in different brain regions. RESULTS: BrdU-positive cells were significantly lower in the 800/1000 ppm-4-week group than the control. 1-Week exposure to 1-BP at 800 and 1000 ppm significantly reduced noradrenalin level in the striatum. Four-week exposure at 800 ppm significantly decreased noradrenalin levels in the hippocampus, prefrontal cortex and striatum. 1-BP also reduced hippocampal BDNF and GR mRNA levels. CONCLUSION: Long-term exposure to 1-BP decreased neurogenesis in the dentate gyrus. Downregulation of BDNF and GR mRNA expression and low hippocampal norepinephrine levels might contribute, at least in part, to the reduced neurogenesis.
  • Sahabudeen Sheik Mohideen, Sahoko Ichihara, Kaviarasan Subramanian, Zhenlie Huang, Hisao Naito, Junzoh Kitoh, Gaku Ichihara
    Journal of occupational health 55 (1) 29 - 38 1341-9145 2013 [Refereed][Not invited]
     
    OBJECTIVES: Human cases of 1-bromopropane (1-BP) toxicity showed ataxic gait and cognitive dysfunction, whereas rat studies showed pyknotic shrinkage in cerebellar Purkinje cells and electrophysiological changes in the hippocampus. The present study investigated the effects of 1-BP on astrocytes and oligodendrocytes in the rat cerebellum and hippocampus to find sensitive markers of central nervous system toxicity. METHODS: Forty-eight F344 rats were divided into four equal groups and exposed to 1-BP at 0, 400, 800 and 1,000 ppm for 8 h/day; 7 days/week, for 4 weeks. Nine and three rats per group were used for biochemical and histopathological studies, respectively. RESULTS: Kluver-Barrera staining showed pyknotic shrinkage in the cytoplasm of Purkinje cells and nuclei of granular cells in the cerebellum at 1,000 ppm. Immunohistochemical analysis showed increased length of glial fibrillary acidic protein (GFAP)-positive processes of astrocytes in the cerebellum, hippocampus and dentate gyrus at 800 and 1,000 ppm. The myelin basic protein (MBP) level was lower at 1,000 ppm. The numbers of astrocytes and granular cells per tissue volume increased at 400 ppm or higher. CONCLUSION: The present study showed that elongation of processes of astrocytes accompanies degeneration of granular cells and Purkinje cells in the cerebellum of the rats exposed to 1-BP. The decrease in MBP and number of oligodendrocytes suggest adverse effects on myelination. The increase in astrocyte population per tissue volume in the cerebellum might be a sensitive marker of 1-BP neurotoxicity, but the underlying mechanism for this change remains elusive.
  • Kaviarasan Subramanian, Sahabudeen Sheik Mohideen, Akio Suzumura, Naoya Asai, Yoshiki Murakumo, Masahide Takahashi, Shijie Jin, Lingyi Zhang, Zhenlie Huang, Sahoko Ichihara, Junzoh Kitoh, Gaku Ichihara
    Toxicology 302 (1) 18 - 24 0300-483X 2012/12 [Refereed][Not invited]
     
    1-Bromopropane (1-BP), an alternative to ozone-depleting solvents, is reported to exhibit neurotoxicity and reproductive toxicity in animals and humans. However, the underlying mechanism of the toxicity remains elusive. This study was designed to identify the microglial changes and oxidative stress in the central nervous system (CNS) after 1-BP exposure. Four groups of Wistar-ST rats (n=12 each) were exposed to 0, 400, 800 and 1000ppm of 1-BP, 8h/day for 28 consecutive days. The cerebellum was dissected out in 9 rats of each group and subjected to biochemical analysis, while the brains of the remaining 3 rats were examined immunohistochemically. Exposure to 1-BP increased the levels of oxidative stress markers [thiobarbituric acid reactive substances (TBARS), protein carbonyl and reactive oxygen species (ROS)] in a dose-dependent manner. Likewise, there was also 1-BP dose-dependent increase in nitric oxide (NO) and dose-dependent decrease in protein concentrations in the cerebellum. Immunohistochemical studies showed 1-BP-induced increase in cd11b/c-positive microglia area in the white matter of the cerebellar hemispheres. The results showed that exposure to 1-BP induced morphological change in the microglia and oxidative stress, suggesting that these effects are part of the underlying neurotoxic mechanism of 1-BP in the CNS.
  • Jie Chang, Shinji Oikawa, Gaku Ichihara, Yui Nanpei, Yasuhiro Hotta, Yoshiji Yamada, Saeko Tada-Oikawa, Hitoshi Iwahashi, Emiko Kitagawa, Ichiro Takeuchi, Masao Yuda, Sahoko Ichihara
    Nutrition & metabolism 9 (1) 87 - 87 2012/09 [Refereed][Not invited]
     
    UNLABELLED: BACKGROUND: It is difficult to study the mechanisms of the metabolic syndrome in humans due to the heterogeneous genetic background and lifestyle. The present study investigated changes in the gene and protein profiles in an animal model of the metabolic syndrome to identify the molecular targets associated with the pathogenesis and progression of obesity related to the metabolic syndrome. METHODS: We extracted mRNAs and proteins from the liver tissues of 6- and 25-week-old spontaneously hypertensive/NIH -corpulent rat SHR/NDmcr-cp (CP), SHR/Lean (Lean) and Wistar Kyoto rats (WKY) and performed microarray analysis and two-dimensional difference in gel electrophoresis (2D-DIGE) linked to a matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS). RESULTS: The microarray analysis identified 25 significantly up-regulated genes (P < 0.01; log10 > 1) and 31 significantly down-regulated genes (P < 0.01; log10 < -1) in 6- and 25-week-old CP compared with WKY and Lean. Several of these genes are known to be involved in important biological processes such as electron transporter activity, electron transport, lipid metabolism, ion transport, transferase, and ion channel activity. MALDI-TOF/TOF MS identified 31 proteins with ±1.2 fold change (P < 0.05) in 6- and 25-week-old CP, compared with age-matched WKY and Lean. The up-regulated proteins are involved in metabolic processes, biological regulation, catalytic activity, and binding, while the down-regulated proteins are involved in endoplasmic reticulum stress-related unfolded protein response. CONCLUSION: Genes with significant changes in their expression in transcriptomic analysis matched very few of the proteins identified in proteomics analysis. However, annotated functional classifications might provide an important reference resource to understand the pathogenesis of obesity associated with the metabolic syndrome.
  • Zhenlie Huang, Sahoko Ichihara, Shinji Oikawa, Jie Chang, Lingyi Zhang, Kaviarasan Subramanian, Sahabudeen Sheik Mohideen, Gaku Ichihara
    Toxicology and applied pharmacology 263 (1) 44 - 52 0041-008X 2012/08 [Refereed][Not invited]
     
    1-Bromopropane (1-BP) is neurotoxic in both experimental animals and humans. Previous proteomic analysis of rat hippocampus implicated alteration of protein expression in oxidative stress, suggesting that oxidative stress plays a role in 1-BP-induced neurotoxicity. To understand this role at the protein level, we exposed male F344 rats to 1-BP at 0, 400, or 1000 ppm for 8h/day for 1 week or 4 weeks by inhalation and quantitated changes in hippocampal protein carbonyl using a protein carbonyl assay, two-dimensional gel electrophoresis (2-DE), immunoblotting, and matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF-TOF/MS). Hippocampal reactive oxygen species and protein carbonyl were significantly increased, demonstrating 1-BP-associated induction of oxidative stress and protein damage. MALDI-TOF-TOF/MS identified 10 individual proteins with increased carbonyl modification (p < 0.05; fold-change ≥ 1.5). The identified proteins were involved in diverse biological processes including glycolysis, ATP production, tyrosine catabolism, GTP binding, guanine degradation, and neuronal metabolism of dopamine. Hippocampal triosephosphate isomerase (TPI) activity was significantly reduced and negatively correlated with TPI carbonylation (p < 0.001; r = 0.83). Advanced glycation end-product (AGE) levels were significantly elevated both in the hippocampus and plasma, and hippocampal AGEs correlated negatively with TPI activity (p < 0.001; r = 0.71). In conclusion, 1-BP-induced neurotoxicity in the rat hippocampus seems to involve oxidative damage of cellular proteins, decreased TPI activity, and elevated AGEs.
  • Zhenlie Huang, Sahoko Ichihara, Shinji Oikawa, Jie Chang, Lingyi Zhang, Masahide Takahashi, Kaviarasan Subramanian, Sahabudeen Sheik Mohideen, Yun Wang, Gaku Ichihara
    Toxicology and applied pharmacology 257 (1) 93 - 101 0041-008X 2011/11 [Refereed][Not invited]
     
    1-Bromopropane (1-BP) is a compound used as an alternative to ozone-depleting solvents and is neurotoxic both in experimental animals and human. However, the molecular mechanisms of the neurotoxic effects of 1-BP are not well known. To identify the molecular mechanisms of 1-BP-induced neurotoxicity, we analyzed quantitatively changes in protein expression in the hippocampus of rats exposed to 1-BP. Male F344 rats were exposed to 1-BP at 0, 400, or 1000 ppm for 8h/day for 1 or 4 weeks by inhalation. Two-dimensional difference in gel electrophoresis (2D-DIGE) combined with matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) were conducted to detect and identify protein modification. Changes in selected proteins were further confirmed by western blot. 2D-DIGE identified 26 proteins with consistently altered model (increase or decrease after both 1- and 4-week 1-BP exposures) and significant changes in their levels (p<0.05; fold change ≥ ± 1.2) at least at one exposure level or more compared with the corresponding controls. Of these proteins, 19 were identified by MALDI-TOF-TOF/MS. Linear regression analysis of 1-BP exposure level identified 8 differentially expressed proteins altered in a dose-dependent manner both in 1- and 4-week exposure experiments. The identified proteins could be categorized into diverse functional classes such as nucleocytoplasmic transport, immunity and defense, energy metabolism, ubiquitination-proteasome pathway, neurotransmitter and purine metabolism. Overall, the results suggest that 1-BP-induced hippocampal damage involves oxidative stress, loss of ATP production, neurotransmitter dysfunction and inhibition of ubiquitination-proteasome system.
  • Gaku Ichihara, Hailan Wang, Lingyi Zhang, Kenji Wakai, Weihua Li, Xuncheng Ding, Eiji Shibata, Zhijun Zhou, Qiangyi Wang, Jiefei Li, Sahoko Ichihara, Yasuhiro Takeuchi
    Journal of occupational and environmental medicine 53 (10) 1095 - 8 1076-2752 2011/10 [Refereed][Not invited]
  • Sahabudeen Sheik Mohideen, Gaku Ichihara, Sahoko Ichihara, Shoji Nakamura
    Toxicology 285 (1-2) 67 - 71 0300-483X 2011/07 [Refereed][Not invited]
     
    1-Bromopropane (1-BP) has been used as an alternative to ozone-depleting solvents. Previous studies showed that 1-BP is neurotoxic in animals and humans. In humans, exposure to 1-BP caused various neurological and neurobehavioral symptoms or signs including depressive or irritated mood. However, the neurobiological changes underlying the depressive symptoms induced by 1-BP remain to be determined. The depressive symptoms are thought to be associated with degeneration of axons containing noradrenaline and serotonin. Based on this hypothesis, the present study examined the effects of repeated exposure to 1-BP on serotonergic and noradrenergic axons. Exposure to 1-BP induced dose-dependent decreases in the density of noradrenergic axons in the rat prefrontal cortex, but no apparent change in the density of serotonergic axons. The results suggest that depressive symptoms in workers exposed to 1-BP are due, at least in part, to the degeneration of noradrenergic axons in the brain.
  • Masahiro Nakatochi, Seiko Miyata, Daisuke Tanimura, Hideo Izawa, Hiroyuki Asano, Yosuke Murase, Ryuji Kato, Sahoko Ichihara, Keiko Naruse, Tatsuaki Matsubara, Hiroyuki Honda, Mitsuhiro Yokota
    DIABETES RESEARCH AND CLINICAL PRACTICE 92 (3) E61 - E65 0168-8227 2011/06 [Refereed][Not invited]
     
    We evaluated the ratio of adiponectin level to homeostasis model assessment of insulin resistance (A/H ratio) as a risk marker for metabolic syndrome (MetS) and each of its components. The A/H ratio may prove to be a powerful index for evaluation of risk for MetS and each of its components. (C) 2011 Elsevier Ireland Ltd. All rights reserved.
  • Daisuke Tanimura, Rei Shibata, Hideo Izawa, Akihiro Hirashiki, Hiroyuki Asano, Yosuke Murase, Seiko Miyata, Masahiro Nakatochi, Noriyuki Ouchi, Sahoko Ichihara, Kenji Yasui, Tsutomu Yoshida, Keiko Naruse, Tatsuaki Matsubara, Mitsuhiro Yokota
    EUROPEAN JOURNAL OF HUMAN GENETICS 19 (3) 262 - 269 1018-4813 2011/03 [Refereed][Not invited]
     
    Adiponectin is an adipocyte-derived protein that is down-regulated in obesity-linked disorders. Variants of the adiponectin gene (ADIPOQ) have been shown to affect adiponectin level. We have now examined the relation of polymorphisms of ADIPOQ to adiponectin concentration and to metabolic disorders in the Kita-Nagoya Genomic Epidemiology study, a population-based study of elderly Japanese. The genomic region including ADIPOQ was genotyped for 30 single nucleotide polymorphisms in 500 subjects of a screening population with the use of a fluorescence-or colorimetry-based allele-specific DNA primer-probe assay system. Four polymorphisms were then selected for genotyping in an additional 2797 subjects. Serum adiponectin level was negatively associated with metabolic abnormalities after adjustment for age and sex. The minor alleles of the rs1656930, Ile164Thr, and rs9882205 polymorphisms were associated with a low serum adiponectin level. Whereas the minor alleles of rs1656930 and rs9882205 were common (minor allele frequency of 6.2 and 38.5%, respectively), that of Ile164Thr was rare (0.9%). The minor allele of rs1656930 was positively associated with systolic blood pressure and the prevalence of hypertension. The association of rs1656930 with adiponectin level was replicated in an independent population. A subject with the 164Thr/Thr genotype had an extremely low serum adiponectin level (0.6 mu g/ml) and the phenotype of metabolic syndrome. Our results suggest that a common variant of ADIPOQ, the minor allele of rs1656930, is associated with hypoadiponectinemia and hypertension. Screening for a common genetic background underlying low adiponectin levels might provide important information for assessment and management of metabolic disorders. European Journal of Human Genetics (2011) 19, 262-269; doi:10.1038/ejhg.2010.201; published online 8 December 2010
  • Yoshiji Yamada, Tamotsu Nishida, Sahoko Ichihara, Motoji Sawabe, Noriyuki Fuku, Yutaka Nishigaki, Yukitoshi Aoyagi, Masashi Tanaka, Yoshinori Fujiwara, Hiroto Yoshida, Shoji Shinkai, Kei Satoh, Kimihiko Kato, Tetsuo Fujimaki, Kiyoshi Yokoi, Mitsutoshi Oguri, Tetsuro Yoshida, Sachiro Watanabe, Yoshinori Nozawa, Aki Hasegawa, Toshio Kojima, Bok-Ghee Han, Younjin Ahn, Meehee Lee, Dong-Jik Shin, Jong Ho Lee, Yangsoo Jang
    ATHEROSCLEROSIS 215 (1) 145 - 152 0021-9150 2011/03 [Refereed][Not invited]
     
    Objective: We have performed a genome-wide association study (GWAS) to identify genetic variants that confer susceptibility to myocardial infarction (MI) in Japanese and Korean populations. Methods: A total of 17,447 Japanese or Korean individuals from four independent subject panels was examined. Japanese subject panels A, B, and C comprised 134 individuals with MI and 137 controls, 1431 individuals with MI and 3161 controls, and 643 individuals with MI and 1347 controls, respectively, whereas the Korean population comprised 1880 individuals with MI and 8714 controls. A GWAS for MI was performed in Japanese subject panel A with the use of the Affymetrix GeneChip Human Mapping 500K Array Set. Results: Seventy single nucleotide polymorphisms (SNPs) significantly (P < 1.0 x 10(-7)) associated with MI by the GWAS were examined further in Japanese subject panel B, revealing two SNPs (rs6929846 of BTN2A1, rs2569512 of ILF3) to be significantly (P < 0.0007) associated with MI. The rs6929846 SNP of BTN2A1, but not rs2569512 of ILF3, was also significantly associated with MI in Japanese subject panel C. However, the association of neither rs6929846 nor rs2569512 with MI was replicated in the Korean population. Conclusion: BTN2A1 may be a susceptibility gene for MI in Japanese individuals. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
  • Momen Elshazley, Eiji Shibata, Naomi Hisanaga, Gaku Ichihara, Ashraf A Ewis, Michihiro Kamijima, Sahoko Ichihara, Kiyoshi Sakai, Mitsuo Sato, Masashi Kondo, Yoshinori Hasegawa
    Industrial health 49 (5) 626 - 33 0019-8366 2011 [Refereed][Not invited]
     
    Pleural plaques are asymptomatic focal thickenings of the pleura and considered the hallmark of asbestos exposure. However, it is often difficult to detect pleural plaques on chest x-rays (CXR). In a retrospective study, using chest CT scans of 140 Japanese asbestos-exposed construction workers who have probable or definite findings of pleural plaque on CXR; firstly, we proposed plaque morphology-based classification for CXR findings, and then we examined if those classified findings could be confirmed as pleural plaques on CT scans. Our morphology-based classification of pleural plaque findings included nine types. The percentages of confirmed pleural plaques on CT scans by type (number of confirmed pleural plaque on CT/number of observed on CXR) were 93% (40/43) for straight, 89% (56/63) for diamond, 88% (7/8) for double, 83% (19/23) for tapered medially, 80% (20/25) for parallel, 77% (23/30) for crescent, 79% (11/14) for tenting, 72% (18/25) for tapered-laterally (long type), and 0% (0/9) for tapered-laterally (short type). When added to the ILO classification, morphology-based classification of CXR pleural plaque findings makes its detection easier and hence chest radiograph continues to be a suitable tool for screening asbestos-related pleural plaques based on its simplicity, low radiation exposure, wide availability and cost-effectiveness.
  • Sahoko Ichihara, Yoshiji Yamada, Fang Liu, Toyoaki Murohara, Ken Itoh, Masayuki Yamamoto, Gaku Ichihara
    Arteriosclerosis, thrombosis, and vascular biology 30 (8) 1553 - 61 1079-5642 2010/08 [Refereed][Not invited]
     
    OBJECTIVE: To investigate the potential role of nuclear factor-erythroid 2-related factor 2 (Nrf2) in neovascularization with a murine surgical model of ischemia. METHODS AND RESULTS: The transcription factor Nrf2 protects against oxidative stress by increasing the transcription of genes, including those for several antioxidant enzymes that contain an antioxidant response element. Ischemia was induced by femoral artery ligation in Nrf2-deficient (Nrf2(-/-)) and wild-type mice. Ischemia-induced neovascularization was enhanced in Nrf2(-/-) mice compared with that in wild-type mice. The expression of Nrf2 target genes for heme oxygenase 1 and thioredoxin 1 and the concentration of total glutathione in the ischemic hindlimb were reduced for Nrf2(-/-) mice compared with wild-type mice. The infiltration of inflammatory cells and the abundance of adhesion molecule mRNA were greater in the ischemic hindlimb of Nrf2(-/-) mice than in wild-type mice. The expression of monocyte chemoattractant protein-1, tumor necrosis factor-alpha, cyclooxygenase 2, and angiogenic factors in the ischemic hindlimb was also greater for Nrf2(-/-) mice than for wild-type mice. CONCLUSIONS: The ablation of Nrf2 promoted ischemia-induced neovascularization. This effect likely resulted from impaired antioxidant defense and increased accumulation of reactive oxygen species in endothelial cells; consequently, there was an enhanced inflammatory response.
  • Weihua Li, Eiji Shibata, Zhijun Zhou, Sahoko Ichihara, Hailan Wang, Qiangyi Wang, Jiefei Li, Lingyi Zhang, Kenji Wakai, Yasuhiro Takeuchi, Xuncheng Ding, Gaku Ichihara
    Journal of occupational and environmental medicine 52 (8) 769 - 77 1076-2752 2010/08 [Refereed][Not invited]
     
    OBJECTIVES: To investigate the health effects of 1-bromopropane (1-BP) and its dose-dependency in 1-BP production factories in China. METHODS: Data of 60 female and 26 male workers in three 1-BP factories and the same number of age-, sex-, and region-matched controls were interviewed and examined. The time-weighed average exposure levels of individual workers were estimated. RESULTS: Regression analysis on exposure level showed dose-dependent increase in the distal latency of tibial nerve, threshold for vibration sense in toes, lactate dehydrogenase, thyroid stimulating hormone, and follicle stimulating hormone in female workers. The analysis also showed dose-dependent decrease in sensory nerve conduction velocity of the sural nerve, red blood cell, and hematocrit in female workers. CONCLUSIONS: The results indicate that exposure to 1-BP induces dose-dependent neurotoxicity in female workers.
  • Fang Liu, Sahoko Ichihara, William M Valentine, Ken Itoh, Masayuki Yamamoto, Sahabudeen Sheik Mohideen, Junzoh Kitoh, Gaku Ichihara
    Toxicological sciences : an official journal of the Society of Toxicology 115 (2) 596 - 606 1096-6080 2010/06 [Refereed][Not invited]
     
    1-Bromopropane (1-BP) was introduced as an alternative to ozone-depleting solvents. However, it was found to exhibit neurotoxicity, reproductive toxicity, and hepatotoxicity in rodents and neurotoxicity in human. However, the mechanisms underlying the toxicities of 1-BP remain elusive. The present study investigated the role of oxidative stress in 1-BP-induced hepatotoxicity using nuclear factor erythroid 2-related factor 2 (Nrf2)-null mice. Groups of 24 male Nrf2-null mice and 24 male wild-type (WT) C57BL/6J mice were each divided into three groups of eight and exposed to 1-BP at 0, 100, or 300 ppm for 8 h/day for 28 days by inhalation. Liver histopathology showed significantly larger area of necrosis in Nrf2-null mice relative to WT mice at the same exposure level. Nrf2-null mice also had greater malondialdehyde (MDA) levels, higher ratio of oxidized glutathione/reduced form of glutathione, and lower total glutathione content. The constitutive level and the increase in ratio per exposure level of glutathione S-transferase (GST) activity were lower in the liver of Nrf2-null mice than WT mice. Exposure to 1-BP at 300 ppm increased the messenger RNA levels of heme oxygenase-1 (HO-1), glutamate-cysteine ligase modifier subunit (GcLm), glutamate-cysteine synthetase (GcLc), glutathione reductase, and NAD(P)H: quinone oxidoreductase 1 (NQO1) in WT mice but not in Nrf2-null mice except for GST Yc2. Nrf2-null mice were more susceptible to 1-BP-induced hepatotoxicity. That oxidative stress plays a role in 1-BP hepatotoxicity is deduced from the low expression levels and activities of antioxidant enzymes and high MDA levels in Nrf2-null mice.
  • Yosuke Kato, Mitsunori Iwase, Sahoko Ichihara, Hiroaki Kanazawa, Katsunori Hashimoto, Akiko Noda, Kohzo Nagata, Yasuo Koike, Mitsuhiro Yokota
    CIRCULATION JOURNAL 74 (1) 163 - 170 1346-9843 2010/01 [Refereed][Not invited]
     
    Background: Growth hormone-releasing peptide (GHRP) may act directly on the myocardium and improve left ventricular (LV) function, suggesting a potential new approach to the treatment of cardiomyopathic hearts. The present study tested the hypothesis that the beneficial cardiac effects of GHRP might include attenuation of myocardial oxidative stress. Methods and Results: Dilated cardiomyopathic TO-2 hamsters were injected with GHRP-2 (1 mg/kg) or saline from 6 to 12 weeks of age. F1B hamsters served as controls. Untreated TO-2 hamsters progressively developed LV dilation, wall thinning, and systolic dysfunction between 6 and 12 weeks of age. Marked myocardial fibrosis was apparent in untreated hamsters at 12 weeks of age in comparison with F1B controls. The ratio of reduced to oxidized glutathione (GSH/GSSG) was decreased and the concentration of 4-hydroxynonenal (4-HNE) was increased in the hearts of untreated TO-2 hamsters. Treatment with GHRP-2 attenuated the progression of LV remodeling and dysfunction, as well as myocardial fibrosis, in TO-2 hamsters. GHRP-2 also inhibited both the decrease in the GSH/GSSG ratio and the increase in the concentration of 4-HNE in the hearts of TO-2 hamsters. Conclusions: GHRP-2 can suppress the increase in the level of myocardial oxidative stress, leading to attenuation of progressive LV remodeling and dysfunction in dilated cardiomyopathic hamsters. (Circ J 2010; 74: 163-170)
  • Sahabudeen Sheik Mohideen, Sahoko Ichihara, Shameema Banu, Fang Liu, Junzoh Kitoh, Gaku Ichihara
    Neurotoxicology 30 (6) 1078 - 83 0161-813X 2009/11 [Refereed][Not invited]
     
    1-Bromopropane (1-BP), an alternative to ozone-depleting solvents, exhibits neurotoxicity and reproductive toxicity in animals and humans. The present study investigated the effects of exposure to 1-BP on expression of neurotransmitter receptor genes in the rat brain to explore possible biomarkers for central neurotoxicity and find brain regions sensitive for microarray analysis. Thirty-six F344 rats were divided at random into four equal groups of nine and exposed to 1-BP at 0, 400, 800 and 1000 ppm for 8 h/day; 7 days/week for 4 weeks. Total RNA from different brain regions was extracted and real-time PCR was conducted to quantify the mRNA levels of serotonin, dopamine and GABA receptors. Western blot analysis for specific regions of interest was also carried out to determine the protein levels. The mRNAs of 5HTr2a, D2R and GABAa1 were down regulated in a 1-BP dose-dependent manner in the hippocampus. The mRNA levels of 5HTr1a, 5HTr2a, D1R and GABAa1 were significantly decreased in the cortex of rats exposed to 800 ppm, but not to 1000 ppm. The mRNAs of 5HTr1a and 5HTr3a in the pons-medulla were decreased in rats exposed to 400 ppm or higher concentrations. The mRNA expression of D2R in the hippocampus and 5HTr1a and 5HTr3a in the pons-medulla oblongata were the most sensitive indicators of 1-BP neurotoxicity. The results suggest that mRNA expression analysis is useful in identifying brain regions susceptible to 1-BP, as well as providing potential biomarkers for central nervous system toxicity.
  • Fang Liu, Sahoko Ichihara, Sahabudeen Sheik Mohideen, Uka Sai, Junzoh Kitoh, Gaku Ichihara
    Toxicological sciences : an official journal of the Society of Toxicology 112 (1) 100 - 10 1096-6080 2009/11 [Refereed][Not invited]
     
    Previous studies indicate that 1-bromopropane (1BP) has neurotoxicity and reproductive toxicity both in humans and animals. The present study investigated strain differences in susceptibility to 1BP and identified possible biological factors that determine such susceptibility. Twenty-four male mice of each of the three strains (C57BL/6J, DBA/2J, and BALB/cA) were divided into four groups of six each and exposed to 1BP at 0, 50, 110, and 250 ppm for 8 h/day for 28 days by inhalation. At the end of exposure period, the relative susceptibilities of each strain to 1BP-mediated hepatotoxicity and male reproductive toxicity were evaluated. The contributing factors to strain-dependent susceptibility were assessed by determination of hepatic CYP2E1 levels, glutathione-S-transferase (GST) activity, glutathione (GSH) status, and NAD(P)H:quinone oxidoreductase and heme oxygenase-1 mRNA levels. Liver histopathology showed significantly larger area of liver necrosis and more degenerative lobules in BALB/cA in the order of BALB/cA > C57BL/6J > DBA/2J. BALB/cA showed higher CYP2E1 protein level and lower total GSH content and GST activity in the liver than DBA/2J. These results indicate that BALB/cA mice are the most susceptible to hepatotoxicity of 1BP among the three strains tested, and that CYP2E1, GSH level/GST activity may contribute to the susceptibility to 1BP hepatotoxicity. Exposure to > or = 50 ppm of 1BP also decreased sperm count and sperm motility and increased sperms with abnormal heads in all three strains mice in a dose-dependent manner. Comparison with previous studies in rats indicates that mice are far more susceptible than rats to 1BP regarding hepatotoxicity and reproductive toxicity.
  • Sahoko Ichihara, Yoshiji Yamada, Frank J Gonzalez, Tamie Nakajima, Toyoaki Murohara, Gaku Ichihara
    Biochemical and biophysical research communications 381 (1) 44 - 9 0006-291X 2009/03 [Refereed][Not invited]
     
    We have investigated the effect of benzo[a]pyrene (B[a]P), a carcinogen of tobacco smoke and an agonist for the aryl hydrocarbon receptor (AHR), on hypoxia-induced angiogenesis. Ischemia was induced by femoral artery ligation in wild-type and AHR-null mice, and the animals were subjected to oral administration of B[a]P (125 mg/kg) once a week. Exposure to B[a]P up-regulated the expression of metallothionein in the ischemic hindlimb and markedly inhibited ischemia-induced angiogenesis in wild-type mice. The amounts of interleukin-6 and of vascular endothelial growth factor (VEGF) mRNA in the ischemic hindlimb of wild-type mice were reduced by exposure to B[a]P. These various effects of B[a]P were markedly attenuated in AHR-null mice. Our observations suggest that the loss of the inhibitory effect of B[a]P on ischemia-induced angiogenesis apparent in AHR-null mice may be attributable to maintenance of interleukin-6 expression and consequent promotion of angiogenesis through up-regulation of VEGF expression.
  • Yoshiji Yamada, Sahoko Ichihara, Tamotsu Nishida
    CURRENT PHARMACEUTICAL DESIGN 14 (33) 3590 - 3600 1381-6128 2008/11 [Refereed][Not invited]
     
    Despite recent advances in acute stroke therapy, stroke remains the leading cause of severe disability and the third leading cause of death, after heart disease and cancer, in Western countries and Japan. The identification of biomarkers of stroke risk is thus important both for risk prediction and for intervention to avert future events. Although genetic linkage analyses of families and sib-pairs as well as candidate gene and genome-wide association studies have implicated several loci and candidate genes in predisposition to ischemic or hemorrhagic stroke, the genes that contribute to genetic susceptibility to these conditions remain to be identified definitively. Given that vascular inflammation has been recognized as an important mechanism of atherosclerotic disease, proinflammatory genes may play pivotal roles in the pathogenesis of ischemic stroke. In this review, we summarize candidate genes that have been implicated in common forms of ischemic stroke by linkage analyses and association studies. We also review in more detail studies that have revealed an association of ischemic stroke with polymorphisms of proinflammatory genes of particular interest (LTA, IL6, and ALOX5AP) as well as with polymorphisms at chromosomal region 9p21.3, which has recently been identified as a susceptibility locus for coronary heart disease. Such studies may provide insight into the function of implicated genes as well as into the role of genetic factors in the development of ischemic stroke.
  • Yoshiji Yamada, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Kimihiko Kato, Takeshi Hibino, Kiyoshi Yokoi, Sachiro Watanabe, Sahoko Ichihara, Yukitoshi Aoyagi, Akitomo Yasunaga, Hyuntae Park, Masashi Tanaka, Yoshinori Nozawa
    Stroke 39 (8) 2211 - 8 0039-2499 2008/08 [Refereed][Not invited]
     
    BACKGROUND AND PURPOSE: Although genetic epidemiologic studies have implicated several genetic variants as risk factors for ischemic or hemorrhagic stroke, the genetic determinants of these conditions remain largely unknown. We performed an association study to identify gene polymorphisms that confer susceptibility to atherothrombotic cerebral infarction, intracerebral hemorrhage, or subarachnoid hemorrhage. METHODS: The study population comprised 3432 unrelated Japanese individuals: 1362 stroke patients (822 with atherothrombotic cerebral infarction, 333 with intracerebral hemorrhage, and 207 with subarachnoid hemorrhage) and 2070 controls. The genotypes for 50 polymorphisms of 38 candidate genes were determined by a method that combines the polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. RESULTS: An initial chi(2) test (false discovery rate <0.05) and subsequent multivariable logistic-regression analysis with adjustment for conventional risk factors (P<0.05) revealed that the -14C-->T polymorphism (rs1800977) of ABCA1, the A-->C (rs3027898) and C-->T (Ser532Leu, rs1059703) polymorphisms of IRAK1, and the G-->C (Cys2229Ser) polymorphism (rs619203) of ROS1 were significantly associated with atherothrombotic cerebral infarction; that the -428G-->A polymorphism (rs710968) of LIMK1 was significantly associated with intracerebral hemorrhage; and that the 13989A-->G (Ile118Val) polymorphism (NC_000007.12) of CYP3A4 was significantly associated with subarachnoid hemorrhage. CONCLUSIONS: Genotypes for ABCA1, IRAK1, and ROS1 may prove useful for assessment of the genetic risk for atherothrombotic cerebral infarction, whereas those for LIMK1 and CYP3A4 may be similarly beneficial in assessment of the genetic risk for intracerebral hemorrhage and subarachnoid hemorrhage, respectively. Validation of these findings will require additional studies with independent subject panels.
  • Sahoko Ichihara, Yoshiji Yamada, Kimihiko Kato, Takeshi Hibino, Kiyoshi Yokoi, Hitoshi Matsuo, Tai Kojima, Sachiro Watanabe, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Yukitoshi Aoyagi, Akitomo Yasunaga, Hyuntae Park, Masashi Tanaka, Yoshinori Nozawa
    Genomics 91 (6) 512 - 6 0888-7543 2008/06 [Refereed][Not invited]
     
    The aim of the present study was to identify gene polymorphisms that confer susceptibility to obesity. A total of 5448 unrelated Japanese individuals from two independent populations were examined: subject panel A comprised 4252 individuals who visited participating hospitals; subject panel B comprised 1196 community-dwelling elderly individuals. The genotypes for 95 polymorphisms of 67 candidate genes were determined. The chi(2) test revealed that six polymorphisms were related (p<0.05) to the prevalence of obesity in subject panel A; after application of Bonferroni's correction, however, only the 2677G --> A/T polymorphism (rs2032582) of the ATP-binding cassette, subfamily B, member 1 gene (ABCB1) was significantly associated (p=0.0003) with obesity. Subsequent multivariable logistic regression analysis also revealed that the 2677G --> A/T polymorphism of ABCB1 was significantly associated with obesity. For validation of this association, the 2677G --> A/T polymorphism of ABCB1 was examined in subject panel B and again found to be significantly associated with obesity. Body mass index was significantly (p=0.01) greater for individuals with the variant T allele of this polymorphism than for those with the GG genotype in the combined subject panels A and B. Our results suggest that the ABCB1 genotype may prove informative for assessment of genetic risk for obesity in Japanese individuals.
  • Yoshiji Yamada, Kimihiko Kato, Mitsutoshi Oguri, Tetsuro Yoshida, Kiyoshi Yokoi, Sachiro Watanabe, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Sahoko Ichihara, Yukitoshi Aoyagi, Akitomo Yasunaga, Hyuntae Park, Masashi Tanaka, Yoshinori Nozawa
    International journal of molecular medicine 21 (6) 801 - 8 1107-3756 2008/06 [Refereed][Not invited]
     
    Metabolic syndrome is a risk factor for cardiovascular disease. The aim of the present study was to identify genetic variants that confer susceptibility to atherothrombotic cerebral infarction among individuals with metabolic syndrome in order to allow prediction of genetic risk for this condition. The study population comprised 1284 unrelated Japanese individuals with metabolic syndrome, including 313 subjects with atherothrombotic cerebral infarction and 971 controls. The genotypes for 296 polymorphisms of 202 candidate genes were determined with a method that combines the polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. The Chi-square test, multivariable logistic regression analysis with adjustment for age, sex, body mass index, and the prevalence of hypertension, hypercholesterolemia, and diabetes mellitus, as well as a stepwise forward selection procedure revealed that the 2445G-->A (Ala54Thr) polymorphism (rs1799883) of FABP2, the -108/3G-->4G polymorphism of IPF1 (S82168), the A-->G (Thr94Ala) polymorphism (rs2241883) of FABP1, the G-->A (Asp2213Asn) polymorphism (rs529038) of ROS1, the -11377C-->G polymorphism (rs266729) of ADIPOQ, the 162A-->C polymorphism (rs4769055) of ALOX5AP, the -786T-->C polymorphism (rs2070744) of NOS3, and the 3279C-->T polymorphism (rs7291467) of LGALS2 were associated (P<0.05) with the prevalence of atherothrombotic cerebral infarction. Among these polymorphisms, the 2445G-->A (Ala54Thr) polymorphism of FABP2 was most significantly associated with this condition. Our results suggest that FABP2, IPF1, FABP1, ROS1, ADIPOQ, ALOX5AP, NOS3, and LGALS2 are susceptibility loci for atherothrombotic cerebral infarction among Japanese individuals with metabolic syndrome. Genotypes for these polymorphisms, especially for the 2445G-->A (Ala54Thr) polymorphism of FABP2, may prove informative for the prediction of genetic risk for atherothrombotic cerebral infarction among such individuals.
  • Yoshiji Yamada, Kimihiko Kato, Tetsuro Yoshida, Kiyoshi Yokoi, Hitoshi Matsuo, Sachiro Watanabe, Sahoko Ichihara, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Yukitoshi Aoyagi, Akitomo Yasunaga, Hyuntae Park, Masashi Tanaka, Yoshinori Nozawa
    International journal of molecular medicine 21 (1) 83 - 9 1107-3756 2008/01 [Refereed][Not invited]
     
    Although various environmental factors, such as a high-salt diet, a smoking habit, excessive alcohol intake, and physical inactivity, influence the development of hypertension, genetic variation also contributes to an individual's susceptibility to this condition. The purpose of the present study was to identify gene polymorphisms that confer susceptibility or resistance to hypertension, and thereby contribute to the prediction of the genetic risk for this condition. The study population comprised 2752 unrelated Japanese individuals (1370 men, 1382 women), including 1276 subjects with hypertension (774 men, 502 women) and 1476 controls (596 men, 880 women). The genotypes for 50 polymorphisms of 35 candidate genes were determined by a method that combines polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. Evaluation of genotype distributions by the Chi-square test and subsequent multivariable logistic regression analysis with adjustment for age, sex, body mass index, smoking status, and the prevalence of diabetes mellitus and hypercholesterolemia revealed that the -14C-->T polymorphism of ABCA1, the C-->G (Ser2229Cys) polymorphism of ROS1, the C-->T (Asn591Asn) polymorphism of LDLR, the 13989A-->G (Ile118Val) polymorphism of CYP3A4, the C-->G and A-->C polymorphisms of ADIPOR1, and the -519A-->G polymorphism of MMP1 were significantly (P<0.05) associated with the prevalence of hypertension. Systolic and diastolic blood pressure differed significantly among genotypes for the -14C-->T polymorphism of ABCA1 and the C-->G (Ser2229Cys) polymorphism of ROS1, with the variant T and G alleles, respectively, being related to increased blood pressure. These results suggest that polymorphisms of ABCA1 and ROS1 are determinants of blood pressure and the development of hypertension in Japanese individuals. Determination of genotypes for ABCA1 and ROS1 may thus prove informative for the prediction of the genetic risk for hypertension.
  • Yoshiji Yamada, Sahoko Ichihara, Tamotsu Nishida
    Genomic Medicine 2 (1-2) 7 - 22 1871-7934 2008/01 [Refereed][Not invited]
     
    Myocardial infarction (MI) is an important clinical problem because of its large contribution to mortality. The main causal and treatable risk factors for MI include hypertension, hypercholesterolemia or dyslipidemia, diabetes mellitus, and smoking. In addition to these risk factors, recent studies have shown the importance of genetic factors and interactions between multiple genes and environmental factors. Disease prevention is an important strategy for reducing the overall burden of MI, with the identification of markers for disease risk being key both for risk prediction and for potential intervention to lower the chance of future events. Although genetic linkage analyses of families and sib-pairs as well as candidate gene and genome-wide association studies have implicated several loci and candidate genes in predisposition to coronary heart disease (CHD) or MI, the genes that contribute to genetic susceptibility to these conditions remain to be identified definitively. In this review, we summarize both candidate loci for CHD or MI identified by linkage analyses and candidate genes examined by association studies. We also review in more detail studies that have revealed the association with MI or CHD of polymorphisms in MTHFR, LPL, and APOE by the candidate gene approach and those in LTA and at chromosomal region 9p21.3 by genome-wide scans. Such studies may provide insight into the function of implicated genes as well as into the role of genetic factors in the development of CHD and MI. © 2008 Springer Science+Business Media B.V.
  • Shameema Banu, Sahoko Ichihara, Fen Huang, Hidenori Ito, Yutaka Inaguma, Koichi Furuhashi, Yoshinobu Fukunaga, Qiangyi Wang, Junzoh Kitoh, Hisao Ando, Fumitaka Kikkawa, Gaku Ichihara
    Toxicological sciences : an official journal of the Society of Toxicology 100 (2) 504 - 12 1096-6080 2007/12 [Refereed][Not invited]
     
    Previous experiments indicated that 1-bromopropane (1-BP), an alternative to chloroflurocarbons, is neurotoxic and inhibits spermiation in the testis. Here we investigated the reversibility of the toxic effects of 1-BP in rats. Male Wistar rats were divided into three equal groups of 24 each and exposed by inhalation to 0, 400 or 1000 ppm of 1-BP for 6 weeks (8 hrs/day, 7 days/week). Eight rats from each group were sacrificed at the end of 6 weeks exposure, and at 4 and 14 weeks after the end of exposure, to assess the recovery processes. We studied sperm count, motility, morphology and testicular histopathology, as well as blood pressure, skin temperature and hindlimb muscle strength. At the end of 6 weeks of exposure to 1000 ppm (0 week recovery), testicular weight, epididymal weight, sperm count and motility were low, morphologically abnormal sperm were increased and spermatogenic cells showed diffuse degeneration. These changes did not show full recovery at 14 weeks recovery, with the exception of the prostate and seminal vesicular weights, which recovered back to control values. At 400 ppm, increased retained spermatids at 0 week recovery returned to normal at 4 weeks recovery. Exposure to 1000 ppm produced sustained reduction of hindlimb muscle strength at 14 weeks recovery, whereas normalization of the skin temperature and blood pressure was noted after transient changes. Our study showed that the effect of 1-BP on spermatogenesis is dose-dependent; low exposure inhibited spermiation and hormone-dependent organ weight reduction and these changes were transient, while a higher dose of 1000 ppm 1-BP caused persistent depletion of spermatogenic cells.
  • Yoshiji Yamada, Hitoshi Matsuo, Sachiro Watanabe, Kimihiko Kato, Kazuhiro Yajima, Takeshi Hibino, Kiyoshi Yokoi, Sahoko Ichihara, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Yoshinori Nozawa
    INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE 20 (5) 703 - 707 1107-3756 2007/11 [Refereed][Not invited]
     
    Although several environmental factors, including a high-calorie diet and physical inactivity, influence the development of type 2 diabetes mellitus, genetic factors have been shown to contribute to individual susceptibility to this condition. The purpose of the present study was to identify gene polymorphisms that confer susceptibility or resistance to type 2 diabetes mellitus, and thereby to contribute to assessment of the genetic risk for this condition. The study population comprised 52.59 unrelated Japanese individuals (2980 men, 2279 women), including 1640 subjects with type 2 diabetes mellitus (1071 men, 569 women) and 3619 controls (1909 men, 1710 women). The genotypes for 94 polymorphisms of 67 genes were determined with a method that combines the polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. Evaluation of genotype distributions by the chi-square test revealed that the 13989A -> G (I1e118Va1) polymorphism of the cytochrome P450, subfamily IIIA, polypeptide 4 gene (CYP3A4) was significantly (false discovery rate, 0.000009) associated with the prevalence of type 2 diabetes mellitus. Multivariable logistic regression analysis with adjustment for age and sex also revealed that the 13989A -> G (Ile118Va1) polymorphism of CYP3A4 was significantly (P=0.00002) associated with the prevalence of type 2 diabetes mellitus, with the AG genotype being protective against this condition. Genotyping for CYP3A4 may thus prove informative for assessment of the genetic risk for type 2 diabetes mellitus.
  • Yoshiji Yamada, Hitoshi Matsuo, Shunichiro Warita, Sachiro Watanabe, Kimihiko Kato, Mitsutoshi Oguri, Kiyoshi Yokoi, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Sahoko Ichihara, Yukitoshi Aoyagi, Akitomo Yasunaga, Hyuntae Park, Masashi Tanaka, Yoshinori Nozawa
    Genomics 90 (5) 551 - 8 0888-7543 2007/11 [Refereed][Not invited]
     
    The purpose of the present study was to identify genetic variants that confer susceptibility to dyslipidemia. A total of 5213 individuals from two independent populations were examined: Subject panel A comprised 3794 individuals who visited participating hospitals; subject panel B comprised 1419 community-dwelling elderly individuals. The genotypes for 100 polymorphisms of 65 candidate genes were determined. The chi(2) test and multivariable logistic regression analysis revealed that seven polymorphisms of APOA5, APOC3, APOA1, ACAT2, and LPL were significantly associated with hypertriglyceridemia, six polymorphisms of APOA5, LIPC, and CYP3A4 with low HDL-cholesterol, and three polymorphisms of APOE and CCR2 with high LDL-cholesterol in subject panel A. For validation of these associations, the same polymorphisms were examined in subject panel B. Six polymorphisms of APOA5, APOC3, APOA1, and LPL were again significantly associated with hypertriglyceridemia, three polymorphisms of APOA5 with low HDL-cholesterol, and two polymorphisms of APOE with high LDL-cholesterol. Serum triglyceride, HDL-cholesterol, and LDL-cholesterol concentrations differed significantly among genotypes of these corresponding polymorphisms in both subject panels. These results indicate that polymorphisms of APOA5, APOC3, APOA1, and LPL are determinants of hypertriglyceridemia and that those of APOA5 and APOE are determinants of low HDL-cholesterol and high LDL-cholesterol, respectively, in Japanese individuals.
  • Aya Matsushita, Mitsunori Iwase, Yosuke Kato, Sahoko Ichihara, Gaku Ichihara, Hirotaka Kimata, Keiko Hayashi, Katsunori Hashimoto, Toyoharu Yokoi, Akiko Noda, Yasuo Koike, Mitsuhiro Yokota, Kohzo Nagata
    Experimental animals 56 (5) 339 - 48 1341-1357 2007/10 [Refereed][Not invited]
     
    Sepsis is characterized by various symptoms, signs and underlying pathophysiology. To investigate possible mechanisms underlying this diversity, we compared the cardiovascular effects of lipopolysaccharide (LPS) derived from Escherichia coli (E-LPS) with those of LPS from Pseudomonas aeruginosa (P-LPS) in rats. We also examined the possible roles of tumor necrosis factor-alpha (TNF-alpha) and oxidative stress in LPS-induced cardiovascular damage. E-LPS (10 mg/kg body weight) or P-LPS (2 mg/kg body weight) was administered intravenously to Wistar rats. Echocardiography was serially performed. E-LPS induced an increase in left ventricular fractional shortening that persisted for at least 6 h, whereas P-LPS elicited an initial increase and a subsequent decrease in this parameter. Histological analysis revealed that P-LPS induced interstitial edema, congestion, intramyocardial bleeding, myocardial necrosis, infiltration of inflammatory cells, and formation of fibrin thrombi in the heart, whereas no pathological changes were apparent in the hearts of rats treated with E-LPS. Furthermore, the plasma concentration of TNF-alpha in rats treated with P-LPS was greater than that in rats treated with E-LPS, but the glutathione redox ratio in the heart was not affected by either type of LPS. In conclusion, E-LPS and P-LPS induced distinct patterns of functional and structural responses in the cardiovascular systems of rats. These differential responses may be attributable in part to the difference in the associated increases in the plasma concentration of TNF-alpha. The cardiovascular effects of LPS thus depend on the causative organisms.
  • Sahoko Ichihara, Yoshiji Yamada, Yoshichika Kawai, Toshihiko Osawa, Koichi Furuhashi, Zhiwen Duan, Gaku Ichihara
    Biochemical and biophysical research communications 359 (1) 27 - 33 0006-291X 2007/07 [Refereed][Not invited]
     
    Cardiotoxicity is a treatment-limiting side effect of the anticancer drug doxorubicin (DOX). We have now investigated the roles of oxidative stress and signaling by the protein kinase Akt in DOX-induced cardiotoxicity as well as the effects on such toxicity both of fenofibrate, an agonist of peroxisome proliferator-activated receptor-alpha, and of polyethylene glycol-conjugated superoxide dismutase (PEG-SOD), an antioxidant. Mice injected intraperitoneally with DOX were treated for 4 days with fenofibrate or PEG-SOD. Fenofibrate and PEG-SOD each prevented the induction of cardiac dysfunction by DOX. Both drugs also inhibited the activation of the transcription factor NF-kappaB and increase in lipid peroxidation in the left ventricle induced by DOX, whereas only PEG-SOD inhibited the DOX-induced activation of Akt and Akt-regulated gene expression. These results suggest that fenofibrate and PEG-SOD prevented cardiac dysfunction induced by DOX through normalization of oxidative stress and redox-regulated NF-kappaB signaling.
  • Sahoko Ichihara, Yoshiji Yamada, Gaku Ichihara, Tamie Nakajima, Ping Li, Takahisa Kondo, Frank J Gonzalez, Toyoaki Murohara
    Arteriosclerosis, thrombosis, and vascular biology 27 (6) 1297 - 304 1079-5642 2007/06 [Refereed][Not invited]
     
    OBJECTIVE: The aryl hydrocarbon receptor (AHR) is a transcription factor that binds to DNA as a heterodimer with the AHR nuclear translocator (ARNT) after interaction with ligands such as polycyclic and halogenated aromatic hydrocarbons found in tobacco smoke and the environment. We have investigated the interaction between AHR and hypoxia signaling pathways in regulation of angiogenesis with the use of a surgical model of ischemia. METHODS AND RESULTS: Ischemia was induced by femoral artery occlusion in wild-type and AHR-null mice. Ischemia-induced angiogenesis was markedly enhanced in AHR-null mice compared with that in wild-type animals. Ischemia-induced upregulation of the expression of hypoxia-inducible factor-1alpha (HIF-1alpha) and ARNT as well as that of target genes for these transcription factors, such as that for vascular endothelial growth factor (VEGF), were also enhanced in AHR-null mice. Furthermore, the DNA binding activity of the HIF-1alpha-ARNT complex as well as the association of HIF-1alpha and ARNT with the VEGF gene promoter were increased by ischemia to a greater extent in AHR-null mice than in wild-type animals. CONCLUSIONS: Ablation of AHR resulted in enhancement of ischemia-induced angiogenesis. This effect was likely attributable in part to the associated enhancement of ischemia-induced VEGF expression, which in turn may be caused by an increased abundance and activity of the HIF-1alpha-ARNT heterodimer.
  • Yoshiji Yamada, Kimihiko Kato, Takeshi Hibino, Kiyoshi Yokoi, Hitoshi Matsuo, Tomonori Segawa, Sachiro Watanabe, Sahoko Ichihara, Hidemi Yoshida, Kei Satoh, Yoshinori Nozawa
    ATHEROSCLEROSIS 191 (2) 298 - 304 0021-9150 2007/04 [Refereed][Not invited]
     
    Objectives: The aim of the study was to identify gene polymorphisms that confer susceptibility to metabolic syndrome in order to allow reliable assessment of genetic risk for this condition. Methods and results: The study population comprised [788 unrelated Japanese individuals (1033 men, 755 women), including 1017 subjects with metabolic syndrome (634 men, 383 women) and 771 controls (399 men, 372 women). The genotypes for 158 polymorphisms of 133 candidate genes were determined with a method that combines the polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. Multivariable logistic regression analysis with adjustment for age, sex, and the prevalence of smoking revealed that the - 1131T -> C polymorphism of the apolipoprotein A-V gene (APOA5) was significantly associated with the prevalence of metabolic syndrome, with the C allele representing a risk factor for this condition. A stepwise forward selection procedure demonstrated that APOA5 genotype (CC+ TC versus TT) significantly affected the prevalence of metabolic syndrome. The C allele of this polymorphism was associated with an increased serum concentration of triglycerides and a decreased concentration of HDL-cholesterol. Conclusions: Genotype for APOA5 may prove reliable for assessment of genetic risk for metabolic syndrome. (c) 2006 Elsevier Ireland Ltd. All rights reserved.
  • Sachiyo Yamaguchi, Yoshiji Yamada, Hitoshi Matsuo, Tomonori Segawa, Sachiro Watanabe, Kimihiko Kato, Kiyoshi Yokoi, Sahoko Ichihara, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Yoshinori Nozawa
    INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE 19 (4) 631 - 637 1107-3756 2007/04 [Refereed][Not invited]
     
    Type 2 diabetes mellitus is a complex metabolic disorder in which endogenous sex hormones may contribute to sex-dependent etiologies. We hypothesized that genetic variants related to type 2 diabetes mellitus might differ between men and women. We thus performed a large-scale association study to identify gene polymorphisms associated with type 2 diabetes mellitus in men and women separately. The study population comprised 4854 unrelated Japanese individuals (2688 men, 2166 women), including 1490 subjects with type 2 diabetes mellitus (969 men, 521 women). The genotypes for 16 gene polymorphisms were determined with a method that combines the polymerase chain reaction and sequence-specific. oligonucleotide probes with suspension array technology. Multivariable logistic regression analysis with adjustment for age, body mass index, and smoking status revealed that the T-G (3' UTR) polymorphism of the thrombospondin 2 gene (THBS2), the -603A -> G polymorphism of the coagulation factor III gene (F3), and the G,T (intron 2) polymorphism of the adipocyte, C1Q, and collagen domain containing (adiponectin) gene (ADIPOQ) were significantly associated with the prevalence of type 2 diabetes mellitus in men, and that the A-G (Arg160Gly) polymorphism of the paraoxonase 1 gene (PON1) was significantly associated with this condition in women. A stepwise forward selection procedure demonstrated that genotypes of THBS2, F3, and ADIPOQ were significant determinants of type 2 diabetes mellitus in men, and that genotype of PON1 significantly affected this condition in women. Genotyping of these polymorphisms may prove informative for assessment of the genetic component of type 2 diabetes mellitus for men and women separately.
  • Kohta Nishihama, Yoshiji Yamada, Hitoshi Matsuo, Tomonori Segawa, Sachiro Watanabe, Kimihiko Kato, Kazuhiro Yajima, Takeshi Hibino, Kiyoshi Yokoi, Sahoko Ichihara, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Yoshinori Nozawa
    INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE 19 (1) 129 - 141 1107-3756 2007/01 [Refereed][Not invited]
     
    The purpose of the present study was to assess the genetic risk for myocardial infarction (MI) in individuals with or without conventional coronary risk factors and thereby to contribute to the personalized prevention of MI in such individuals. The study population comprised 3483 unrelated Japanese individuals (1913 men, 1570 women). The 1192 subjects with MI (926 men, 266 women) and 2291 controls (987 men, 1304 women) either had or did not have conventional coronary risk factors, including hypertension, hypercholesterolemia, and diabetes mellitus. The genotypes for 164 polymorphisms of 137 candidate genes were determined by a method that combines the polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. Multivariable logistic regression analysis and a stepwise forward selection procedure revealed that nine different polymorphisms were significantly (P < 0.005) associated with MI among individuals with or without hypertension, hypercholesterolemia, or diabetes mellitus: 1018C -> T of GP1BA, -108/3G -> 4G of IPF1, 677C -> T of MTHFR, and G -> A of UTS2 in hypertensive individuals; 2445G -> A of FABP2, -108/3G -> 4G of IPFI, 677C -> T of MTHFR, -11,377C -> G of ACDC, A -> G of AKAP10, 11,496G -> A of F7, and 46C -> T of F12 in individuals without hypercholesterolemia; 2445G -> A of FABP2 in diabetic individuals; and -108/3G -> 4G of IPF1 in nondiabetic individuals. Polymorphisms associated with MI may thus differ among individuals with different conventional coronary risk factors. Stratification of subjects on the basis of such risk factors may thus be important in order to achieve personalized prevention of MI with the use of genetic information.
  • Masako Saka, Koji Obata, Sahoko Ichihara, Xian Wu Cheng, Hirotaka Kimata, Akiko Noda, Hideo Izawa, Kohzo Nagata, Mitsuhiro Yokota
    CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY 33 (12) 1164 - 1171 0305-1870 2006/12 [Refereed][Not invited]
     
    1. Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (statins) manifest pleiotropic effects that may contribute to their therapeutic efficacy. However, the mechanism of the beneficial action of statins on cardiac hypertrophy and fibrosis remains unclear. We have now investigated this action of pitavastatin in Dahl salt-sensitive (DS) rats. 2. The DS rats progressively develop marked hypertension when fed a diet containing 8% NaCl from 7 weeks of age. These animals exhibited pronounced cardiac hypertrophy and fibrosis, as well as upregulation of fetal-type cardiac gene expression at 12 weeks of age, compared with DS rats fed a diet containing 0.3% NaCl. The abundance of mRNAs for collagen types I and III, angiotensin-converting enzyme, transforming growth factor-beta 1 and connective tissue growth factor was also increased in the heart of rats on the high-salt diet. 3. Treatment of rats on the high-salt diet with a non-antihypertensive dose of pitavastatin (0.3 or 1 mg/kg per day) from 7 to 12 weeks of age attenuated the development of cardiac hypertrophy and fibrosis, as well as inhibiting the upregulation of cardiac gene expression. Pitavastatin also blocked the translocation of RhoA to the membrane fraction of the left ventricle and RhoA activation, as well as the phosphorylation of the mitogen-activated protein kinases extracellular signal-regulated kinase (ERK)-1 and ERK-2 and an increase in the DNA binding activity of serum response factor (SRF) in the heart induced by the high-salt diet. 4. These findings suggest that the effects of pitavastatin on load-induced cardiac hypertrophy and fibrosis are independent of its cholesterol-lowering action and may be mediated, at least in part, through inhibition of RhoA-ERK-SRF signalling.
  • Sahoko Ichihara, Yoshiji Yamada, Gaku Ichihara, Hiroaki Kanazawa, Katsunori Hashimoto, Yosuke Kato, Aya Matsushita, Shinji Oikawa, Mitsuhiro Yokota, Mitsunori Iwase
    Biochemical and biophysical research communications 350 (1) 105 - 13 0006-291X 2006/11 [Refereed][Not invited]
     
    Oxidative stress is an important susceptibility factor for dilated cardiomyopathy. We have investigated the effects of bisoprolol, a beta1-selective adrenoceptor blocker, on oxidative stress and the development of cardiac dysfunction in a model of dilated cardiomyopathy. Male TO-2 and control hamsters at 8 weeks of age were treated with bisoprolol (5 mg/kg per day) or vehicle for 4 weeks. Treatment with bisoprolol prevented the progression of cardiac dysfunction in TO-2 hamsters. This drug did not affect the increase in NADPH oxidase activity but prevented the reduction in activity and expression of mitochondrial manganese-dependent superoxide dismutase as well as the increases in the concentrations of interleukin-1beta and tumor necrosis factor-alpha in the left ventricle of TO-2 hamsters. Attenuation of the development of cardiac dysfunction by bisoprolol may thus result in part from normalization of the associated increases in the levels of oxidative stress and pro-inflammatory cytokines in the left ventricle.
  • Yoshiji Yamada, Kimihiko Kato, Takashi Kameyama, Kiyoshi Yokoi, Hitoshi Matsuo, Tomonori Segawa, Sachiro Watanabe, Sahoko Ichihara, Hidemi Yoshida, Kei Satoh, Yoshinori Nozawa
    INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE 18 (5) 843 - 851 1107-3756 2006/11 [Refereed][Not invited]
     
    The purpose of the present study was to identify gene polymorphisms for the reliable assessment of genetic factors for obesity. The study population comprised 3906 unrelated Japanese individuals (2286 men, 1620 women), including 1196 subjects (677 men, 519 women) with obesity (body mass index of >= 25 kg/m(2)) and 2710 controls (1609 men, 1101 women). The genotypes for 147 polymorphisms of 124 candidate genes were determined with a method that combines the polymerases chain reaction and sequence-specific oligonucleotide probes with suspension array technology. Multivariable logistic regression analysis with adjustment for age, sex, and the prevalence of smoking revealed that the 30G -> A polymorphism of GCK, the -240A -> T polymorphism of ACE, and the -482C -> T polymorphism of APOC3 were significantly (P < 0.01) associated with the prevalence of obesity, and the -1989T -> G polymorphism of ESR1 was almost significantly associated. A stepwise forward selection procedure demonstrated that ACE, GCK, and ESR1 genotypes significantly (P < 0.01) and independently affected the prevalence of obesity. Combined genotype analysis for these three polymorphisms yielded a lowest odds ratio of 0.45 for the combined genotypes of AT or TT for ACE, GG for GCK, and GG for ESR1 in comparison with the combined genotypes of AA for ACE, GG for GCK, and TT or TG for ESR1. Genotypes for ACE, GCK, and ESR1 may prove reliable for the assessment of genetic factors for obesity. Determination of the combined genotypes for these genes may contribute to the personalized prevention of this condition.
  • Sachiyo Yamaguchi, Yoshiji Yamada, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Sahoko Ichihara, Kimihiko Kato, Takashi Kameyama, Kiyoshi Yokoi, Hitoshi Matsuo, Tomonori Segawa, Sachiro Watanabe, Yoshinori Nozawa
    INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE 18 (5) 871 - 883 1107-3756 2006/11 [Refereed][Not invited]
     
    The aim of the present study was to assess the genetic risk for atherothrombotic cerebral infarction (ACI) in men and women separately as well as in individuals with or without conventional risk factors for atherosclerosis and thereby to contribute to the personalized prevention of ACI. The study population comprised 2705 unrelated Japanese individuals (1244 men, 1461 women), including 636 subjects (372 men, 264 women) with ACI. Subjects with ACI and controls either had or did not have conventional risk factors for atherosclerosis, including hypertension, hypercholesterolemia, and diabetes mellitus. The genotypes for 202 polymorphisms of 152 candidate genes were determined by a method that combines polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. Multivariable logistic regression analysis and a stepwise forward selection procedure revealed that 11 different polymorphisms were significantly (P < 0.005) associated with ACI in women or men or in individuals with or without hypertension, hypercholesterolemia, or diabetes mellitus: the 584C -> T polymorphism of LIPG, 56656 -> T of EDN1, and G -> A of CCL11 in women; 677C -> T of MTHFR, 1323C -> T of ITGB2. 3932T -> C of APOE, and -231A -> G of EDNRA in men: -572 G -> C of IL6 in hypertensive individuals; -4036 -> A of CCL5 and G-A of COMT in individuals with hypercholesterolemia: and 3932T -> C of APOE and A -> G of TNFSF4 in diabetic individuals. Polymorphisms associated with ACI may thus differ between women and men as well as among individuals with different risk factors. Stratification of subjects on the basis of sex or conventional risk factors for atherosclerosis may therefore be important in order to achieve the personalized prevention of ACI with the use of genetic information.
  • Yoshiji Yamada, Hitoshi Matsuo, Tomonori Segawa, Sachiro Watanabe, Kimihiko Kato, Takeshi Hibino, Kiyoshi Yokoi, Sahoko Ichihara, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Yoshinori Nozawa
    AMERICAN JOURNAL OF HYPERTENSION 19 (11) 1158 - 1165 0895-7061 2006/11 [Refereed][Not invited]
     
    Background: Although genetic epidemiologic studies have suggested that several genetic variants increase the risk for hypertension, the genes that underlie genetic susceptibility to this condition remain to be identified definitively. We have now performed a large-scale association study to identify gene polymorphisms for reliable assessment of the genetic component of hypertension. Methods: The study population comprised 4853 unrelated Japanese individuals, including 2818 subjects with hypertension (1677 men, 1141 women) and 2035 controls (1011 men, 1024 women). The genotypes for 150 polymorphisms of 128 candidate genes were determined with a method that combines the polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. Results: Multivariable logistic regression analysis with adjustment for age, sex, body mass index, and the prevalence of smoking revealed that four polymorphisms (16486 -> A in ITGA2, -306 -> A in GCK, A -> G in SAH, and 1117C -> A in PTGIS) were significantly (P < .01) associated with hypertension. A stepwise forward selection procedure demonstrated that ITGA2, GCK, and PTGIS genotypes significantly affected the prevalence of hypertension. Combined genotype analysis of these polymorphisms yielded a lowest odds ratio of 0.47 for the genotypes of AA or AG for ITGA2, GA or AA for GCK, and CC for PTGIS, which were present in 1.1% and 2.0% of hypertensive and control individuals, respectively. Conclusions: These results suggest that the genotypes for ITGA2, GCK, and PTGIS may prove reliable for the assessment of the genetic component of hypertension. Determination of the combined genotypes for these genes may contribute to personalized prevention of this condition.
  • Yoshiji Yamada, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Sahoko Ichihara, Kimihiko Kato, Takashi Kameyama, Kiyoshi Yokoi, Hitoshi Matsuo, Tomonori Segawa, Sachiro Watanabe, Yoshinori Nozawa
    ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY 26 (8) 1920 - 1925 1079-5642 2006/08 [Refereed][Not invited]
     
    Objective-We performed an association study to identify gene polymorphisms for assessing the genetic risk of ischemic or hemorrhagic stroke. Methods and Results-The study population comprised 3151 unrelated Japanese individuals: 1141 stroke patients (636 with atherothrombotic cerebral infarction, 282 with intracerebral hemorrhage, and 223 with subarachnoid hemorrhage) and 2010 controls. The genotypes for 202 polymorphisms of 152 genes were determined by suspension array technology. Multivariable logistic regression analysis with adjustment for conventional risk factors revealed that the -572G -> C polymorphism of the interleukin-6 (IL-6) gene (IL6) was significantly (P < 0.001) associated with both atherothrombotic cerebral infarction and intracerebral hemorrhage and that the -55C -> T polymorphism of the uncoupling protein 3 gene (UCP3), the -863C -> A polymorphism of the tumor necrosis factor (TNF) gene (TNF), and the G-A (Gly243Asp) polymorphism of the polycystic kidney disease 1-like gene (PKD1-like) were significantly associated with subarachnoid hemorrhage. Conclusions-IL6 genotype may be useful in assessing the genetic risk for atherothrombotic cerebral infarction and intracerebral hemorrhage, and genotypes for UCP3, TNF, and PKD1-Iike may be similarly beneficial in assessment of the risk for subarachnoid hemorrhage. Validation of our findings will require additional studies with independent subject panels.
  • Sahoko Ichihara, Koji Obata, Yoshiji Yamada, Kohzo Nagata, Akiko Noda, Gaku Ichihara, Akira Yamada, Tomoko Kato, Hideo Izawa, Toyoaki Murohara, Mitsuhiro Yokota
    Journal of molecular and cellular cardiology 41 (2) 318 - 29 0022-2828 2006/08 [Refereed][Not invited]
     
    Peroxisome proliferator-activated receptor-alpha (PPAR-alpha) is a key regulator of lipid and glucose metabolism and is implicated in inflammation. We investigated the effects of the PPAR-alpha activator fenofibrate on, as well as the role of redox-regulated transcription factors, in the development of left ventricular (LV) hypertrophy and heart failure in Dahl salt-sensitive (DS) rats. DS rats were fed a high-salt diet and treated with either fenofibrate (30 or 50 mg/kg per day) or vehicle from 7 weeks of age. Fenofibrate inhibited the development of compensated hypertensive LV hypertrophy, attenuated the LV relaxation abnormality and systolic dysfunction, and improved the survival rate in DS rats. It also prevented a decrease in the ratio of reduced to oxidized glutathione and inhibited up-regulation of the DNA binding activities of the redox-regulated transcription factors NF-kappaB, AP-1, Egr-1, SP1, and Ets-1 induced in the left ventricle by the high-salt diet. Expression of target genes for these transcription factors, including those for adhesion molecules (VCAM-1, ICAM-1), cytokines (MCP-1), growth factors (TGF-beta, PDGF-B), and osteopontin, was also increased by the high-salt diet in a manner sensitive to treatment with fenofibrate. Furthermore, the infiltration of macrophages and T lymphocytes into the left ventricle and the increase in the plasma concentration of C-reactive protein were inhibited by fenofibrate. The PPAR-alpha activator fenofibrate thus attenuated the progression of heart failure and improved the survival rate in this rat model. These effects were associated with inhibition of the inflammatory response and of activation of redox-regulated transcription factors in the left ventricle.
  • Yoshiji Yamada, Hitoshi Matsuo, Tomonori Segawa, Sachiro Watanabe, Kimihiko Kato, Takashi Kameyama, Kiyoshi Yokoi, Sahoko Ichihara, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Yoshinori Nozawa
    INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE 18 (2) 299 - 308 1107-3756 2006/08 [Refereed][Not invited]
     
    The purpose of the present study was to identify gene polymorphisms for reliable assessment of genetic factors for type 2 diabetes mellitus. The study population comprised 4853 unrelated Japanese individuals (2688 men, 2165 women), including 1489 subjects with type 2 diabetes mellitus (969 men, 520 women) and 3364 controls (1719 men, 1645 women). The genotypes for 148 polymorphisms of 124 candidate genes were determined with a method that combines polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. Sixteen polymorphisms were related (p < 0.05) to the prevalence of type 2 diabetes mellitus as determined by the chi-square test. Multivariable logistic regression analysis with adjustment for age, sex, and the prevalence of smoking revealed that, among these polymorphisms, the -603A -> G polymorphism of the gene for coagulation factor III (F3) was significantly (p < 0.001) associated with the prevalence of type 2 diabetes mellitus, with the -603G allele representing a risk factor for this condition. A stepwise forward selection procedure demonstrated that F3 genotype (GG versus AA + AG) significantly (p < 0.00 1) and independently affected the prevalence of type 2 diabetes mellitus. Genotype for F3 may prove reliable for assessment of genetic factors for type 2 diabetes mellitus. Determination of the genotype for this gene may contribute to personalized prevention of this condition.
  • Yoshiji Yamada, Hitoshi Matsuo, Tomonori Segawa, Sachiro Watanabe, Kimihiko Kato, Jakeshi Hibino, Kiyoshi Yokoi, Sahoko Ichihara, Norifumi Metoki, Hidemi Yoshida, Kei Satoh, Yoshinori Nozawa
    THROMBOSIS AND HAEMOSTASIS 96 (2) 220 - 227 0340-6245 2006/08 [Refereed][Not invited]
     
    Although lifestyle and environmental factors influence the prevalence of myocardial infarction, genetic epidemiological studies have suggested that several genetic variants increase the risk for this condition. We have performed a large-scale association study to identify gene polymorphisms for reliable assessment of the genetic risk of myocardial infarction. The study population comprised 3,483 unrelated Japanese individuals (1,913 men; 1,570 women), including 1, 192 subjects with myocardial infarction and 2,291 controls. The genotypes for 164 polymorphisms of 137 candidate genes were determined with an oligonucleotide ligation assay based on analysis of fluorescent microspheres with suspension array technology. Multivariable logistic regression analysis with adjustment for age, sex, body mass index, and the prevalence of smoking, hypertension, diabetes mellitus, and hypercholesterolemia revealed that the 677C -> T (Ala222Val) polymorphism of MTHFR, the 1595C -> G (Ser447Stop) polymorphism of LPL, and the -108/3G -> 4G polymorphism of IPF1 were significantly associated with the prevalence of myocardial infarction. A stepwise forward selection procedure demonstrated that IPF1, MTHFR, and LPL genotypes significantly affected the prevalence of myocardial infarction. Combined genotype analysis of these polymorphisms yielded a maximum odds ratio of 2.54 for the combined genotype of TT for MTHFR, CC for LPL, and 3G3G for IPF1. The genotypes for MTHFR, LPL, and IPF1 may prove reliable for assessment of genetic risk for myocardial infarction. Determination of the combined genotype for these genes may contribute to primary, personalized prevention of this condition.
  • Koichi Furuhashi, Junzoh Kitoh, Hiroko Tsukamura, Kei-Ichiro Maeda, Hailan Wang, Weihua Li, Sahoko Ichihara, Tamie Nakajima, Gaku Ichihara
    Toxicology 224 (3) 219 - 28 0300-483X 2006/07 [Refereed][Not invited]
     
    1-Bromopropane (1-BP) exhibits neuroreproductive toxicities in adult rats and humans. Here, we determined the effects of exposure of rat dams to 1-BP during pregnancy and lactation on the growth and sexual maturation of their offspring. In Experiment 1, 40 rats were exposed to 0, 100, 400 and 800ppm 1-BP during pregnancy and lactation for 8h/day. Ten rats that were not placed in chambers throughout the experiment served to observe the effect of separation of dams from offspring. In Experiment 2, three groups of 10 pregnant rats each were exposed to fresh air in three chambers and 10 other rats were exposed to 800ppm 1-BP during pregnancy and lactation for 8h/day. After delivery, offspring of the exposed and non-exposed dams were swapped so that they were nursed by the opposite dams. In Experiment 1, the survival rate and body weight of offspring were lower than the non-exposed in 1-BP dose-dependent manner. In Experiment 2, the survival rate and body weight of offspring (Group A) nursed by exposed dams and those (Group B) of exposed dams were significantly lower than non-exposed groups. The body weight of Group A was lower than that of Group B, although the two groups showed a significant equal decrease in the survival rate. The number of dead offspring from Group A was significantly higher. Our results indicate that exposure to 1-BP during pregnancy and lactation has comparable effects on survival rate, but exposure during lactation has a more adverse effect on growth of offspring than that during pregnancy. Moreover, exposure during lactation is associated with reduced early survival of third generation (F2) rats.
  • Masako Saka, Koji Obata, Sahoko Ichihara, Xian Wu Cheng, Hirotaka Kimata, Takao Nishizawa, Akiko Noda, Hideo Izawa, Kohzo Nagata, Toyoaki Murohara, Mitsuhiro Yokota
    JOURNAL OF CARDIOVASCULAR PHARMACOLOGY 47 (6) 770 - 779 0160-2446 2006/06 [Refereed][Not invited]
     
    Statin therapy may be associated with lower mortality in patients with heart failure, but the underlying mechanism of such an association is unknown. We have evaluated the effects of pitavastatin on cardiac function and survival in a rat model of hypertensive heart failure and investigated the molecular mechanism of the observed effects. Dahl salt-sensitive rats fed with high-salt diet from 7 weeks of age developed compensatory left ventricular hypertrophy at 12 weeks and heart failure at 19 weeks. Dahl salt-sensitive rats were treated with either vehicle or pitavastatin (0.3 mg/kg per day) from 7 or 12 weeks. Both early-onset and late-onset pitavastatin treatment reduced left ventricular fibrosis, improved cardiac function, and increased the survival rate apparent at 19 weeks. The increases in the expression levels of hypertrophic, profibrotic, and metalloproteinase genes as well as in gelatinase activities in the heart induced by the high-salt diet were suppressed by pitavastatin treatment. Furthermore, the level of cardiac endothelin-1 was increased in association with the development of heart failure in a manner sensitive to treatment with pitavastatin. Both early and late pitavastatin treatment thus improved cardiac function and survival, with modulation of extracellular matrix remodeling and endothelin-1 signaling possibly contributing to these beneficial effects.
  • Nagata K, Obata K, Xu J, Ichihara S, Noda A, Kimata H, Kato T, Izawa H, Murohara T, Yokota M
    Hypertension (Dallas, Tex. : 1979) 47 (4) 656 - 664 0194-911X 2006/04 [Refereed][Not invited]
  • Sahoko Ichihara, Akiko Noda, Kohzo Nagata, Koji Obata, Jinglan Xu, Gaku Ichihara, Shinji Oikawa, Shosuke Kawanishi, Yoshiji Yamada, Mitsuhiro Yokota
    Cardiovascular research 69 (3) 726 - 35 0008-6363 2006/02 [Refereed][Not invited]
     
    OBJECTIVES: Oxidative stress is implicated in the pathogenesis of heart failure and affects the activity of matrix metalloproteinases (MMPs). We have now investigated the role of MMPs and their tissue inhibitors (TIMPs) in the transition from compensated left ventricular (LV) hypertrophy to heart failure as well as the effects of pravastatin on this transition in a rat model. METHODS: Dahl salt-sensitive rats were fed a high-salt (8% NaCl) diet and treated with pravastatin (50 or 100 mg/kg per day) or vehicle from 7 weeks of age. RESULTS: Pravastatin did not attenuate LV hypertrophy apparent at 12 or 18 weeks of age. However, the high dose of this drug markedly improved indices of diastolic function (early diastolic myocardial velocity) and systolic function (LV fractional shortening) at 18 weeks of age and increased the survival rate. It also prevented a decrease in the ratio of reduced to oxidized glutathione and an increase in NADPH oxidase activity in the left ventricle induced by the high-salt diet. The activities of MMP2 and MMP9 and the abundance of TIMP1 and TIMP2 in LV tissue were increased at 18 weeks of age, and pravastatin also prevented these changes. CONCLUSION: Although pravastatin did not attenuate LV hypertrophy, it prevented the transition from compensated hypertrophy to heart failure in this rat model. This effect of pravastatin may result from a reduction both in the level of oxidative stress and in MMP activity in the heart.
  • H Izawa, T Murohara, K Nagata, S Isobe, H Asano, T Amano, S Ichihara, T Kato, S Ohshima, Y Murase, S Iino, K Obata, A Noda, K Okumura, M Yokota
    CIRCULATION 112 (19) 2940 - 2945 0009-7322 2005/11 [Refereed][Not invited]
     
    Background-Mineralocorticoid receptor antagonism reduces mortality associated with heart failure by mechanisms that remain unclear. The effects of the mineralocorticoid receptor antagonist spironolactone on left ventricular (LV) function and chamber stiffness associated with myocardial fibrosis were investigated in mildly symptomatic patients with idiopathic dilated cardiomyopathy (DCM). Methods and Results-Twenty-five DCM patients with a New York Heart Association functional class of I or II were examined before and after treatment with spironolactone for 12 months. LV pressures and volumes were measured simultaneously, and LV endomyocardial biopsy specimens were obtained. Serum concentrations of the carboxyl-terminal propeptide ( PIP) and carboxyl-terminal telopeptide (CITP) of collagen type I were measured. The patients were divided into 2 groups on the basis of the serum PIP/CITP ratio (<= 35, group A, n = 12; > 35, group B, n = 13), an index of myocardial collagen accumulation. LV diastolic chamber stiffness, the collagen volume fraction, and abundance of collagen type I and III mRNAs in biopsy tissue were greater and the LV early diastolic strain rate (tissue Doppler echocardiography) was smaller in group B than in group A at baseline. These differences and the difference in PIP/CITP were greatly reduced after treatment of patients in group B with spironolactone, with treatment having no effect on these parameters in group A. The collagen volume fraction was significantly correlated with PIP/CITP, LV early diastolic strain rate, and LV diastolic chamber stiffness for all patients before and after treatment with spironolactone. Conclusions-Spironolactone ameliorated LV diastolic dysfunction and reduced chamber stiffness in association with regression of myocardial fibrosis in mildly symptomatic patients with DCM. These effects appeared limited, however, to patients with increased myocardial collagen accumulation.
  • JL Xu, K Nagata, K Obata, S Ichihara, H Izawa, A Noda, T Nagasaka, M Iwase, T Naoe, T Murohara, M Yokota
    HYPERTENSION 46 (4) 719 - 724 0194-911X 2005/10 [Refereed][Not invited]
     
    Long-term administration of vasodilators increases shear stress, which is thought to be important for vascular growth in the heart. Nicorandil, an activator of ATP-sensitive potassium channels with a nitrate-like action, is a potent vasodilator. We have now investigated the effects of nicorandil on vascular growth and gene expression in the failing heart of Dahl salt-sensitive (DS) hypertensive rats. DS rats fed a high-salt diet from 6 weeks of age develop concentric cardiac hypertrophy secondary to hypertension at I I weeks, followed by heart failure at IS weeks. DS rats on such a diet were treated with a nonantihypertensive oral dose of nicorandil (6 mg/kg per day) or vehicle from I I to 18 weeks of age. Treatment of DS rats with nicorandil improved cardiac function and attenuated the development of heart failure. Myocardial capillary and arteriolar densities did not differ between vehicle-treated DS rats and age-matched controls. The abundance of mRNAs for endothelial NO synthase (eNOS), vascular endothelial growth factor (VEGF), the VEGF receptor Flt-1, and basic fibroblast growth factor (bFGF) in the myocardium was markedly reduced in vehicle-treated DS rats compared with controls. Treatment of DS rats with nicorandil greatly increased capillary and arteriolar densities and inhibited the downregulation of eNOS, VEGF, fms-like tyrosin kinase-1. and bFGF gene expression. This, nicorandil stimulates coronary capillary and arteriolar growth and thereby likely suppresses the development of heart failure in DS rats. Nicorandil may prove beneficial for the treatment of hypertensive heart failure as well as of ischemic heart disease.
  • Takao Nishizawa, Mitsunori Iwase, Hiroaki Kanazawa, Sahoko Ichihara, Gaku Ichihara, Kohzo Nagata, Koji Obata, Kiyoyuki Kitaichi, Toyoharu Yokoi, Masato Watanabe, Takashi Tsunematsu, Yoshihiro Ishikawa, Toyoaki Murohara, Mitsuhiro Yokota
    Circulation journal : official journal of the Japanese Circulation Society 68 (11) 1051 - 60 1346-9843 2004/11 [Refereed][Not invited]
     
    BACKGROUND: The relationship between enhanced myocardial oxidative stress and impaired beta-adrenergic signaling remains to be characterized during the development of dilated cardiomyopathy. METHODS AND RESULTS: Alterations in myocardial oxidative stress and beta-adrenergic signaling, as well as left ventricular (LV) functional and structural changes, were evaluated during the development of cardiomyopathy in TO-2 hamsters; F1B hamsters served as controls. LV dysfunction was first apparent at 8 weeks of age and deteriorated thereafter in the TO-2 hamsters. At 32 weeks, the animals exhibited heart failure with an increased plasma norepinephrine concentration. Cardiac myolysis, as demonstrated by elevated plasma concentration of cardiac troponin T, peaked at 8 weeks. The glutathione redox ratio revealed increased oxidative stress in the LV myocardium in TO-2 hamsters even at 4 weeks and became manifest after 8 weeks. The hearts of TO-2 hamsters had significantly reduced superoxide dismutase activity from 8 weeks onward compared with control hamsters. However, glutathione peroxidase activity was unchanged at any time point. The LV functional response to isoproterenol was markedly reduced at 8 weeks, without any apparent changes in the amount of beta-adrenergic signaling molecules, and it deteriorated thereafter. Adenylyl cyclase activity was significantly decreased, despite increased amounts of both G(s) alpha mRNA and protein, in the LV myocardium at 18 weeks. CONCLUSIONS: Myocardial oxidative stress is actually enhanced in the initial development of LV dysfunction. Both activation of myocardial oxidative stress and impairment of beta-adrenergic signaling become prominent at the stage of severe LV dysfunction. Myocardial oxidative stress may be involved in the development of beta-adrenergic desensitization.
  • A Yamada, S Ichihara, Y Murase, T Kato, H Izawa, K Nagata, T Murohara, Y Yamada, M Yokota
    JOURNAL OF MOLECULAR MEDICINE-JMM 82 (7) 477 - 483 0946-2716 2004/07 [Refereed][Not invited]
     
    Vascular inflammation plays an important role in the development of myocardial infarction (MI). Lymphotoxin alpha (LTA) is a cytokine with multiple functions in regulation of the immune system and inflammatory reactions. The aim of this study was to examine whether polymorphisms of the LTA gene are associated with the risk of MI in Japanese men and women. A case-control association study was performed for the 252A-->G and 804C-->A polymorphisms of the LTA gene and the prevalence of MI. The study population comprised 3,689 unrelated Japanese individuals (2,486 men, 1,203 women), including 1891 patients with MI (1,493 men, 398 women) and 1798 control subjects (993 men, 805 women). Among the control subjects 257 individuals (108 men, 149 women) who had none of the conventional risk factors for coronary artery disease (CAD) were defined as low-fisk controls. Genotypes for the two polymorphisms were determined with a fluorescence-based allele-specific DNA primer assay system. Among all study subjects the 252A-->G and 804C-->A polymorphisms exhibited linkage disequilibrium. No association of either polymorphism with MI was detected in men or in women in comparisons with total control or low-risk control subjects. However, each of the two polymorphisms was associated with the prevalence of type 2 diabetes mellitus both in men with MI and in those without MI in a recessive genetic model. No association was detected between the polymorphisms and other conventional risk factors for CAD. The LTA gene thus does not appear to be a susceptibility locus for MI in Japanese men or women, although it might affect susceptibility to type 2 diabetes in Japanese men.
  • Y Murase, Y Yamada, A Hirashiki, S Ichihara, H Kanda, M Watarai, F Takatsu, T Murohara, M Yokota
    EUROPEAN HEART JOURNAL 25 (11) 970 - 977 0195-668X 2004/06 [Refereed][Not invited]
     
    Aims The aim of the study was to identify genes that confer susceptibility to coronary artery spasm and clarify the interaction between genetic and environmental factors in this condition. Methods and results The study population comprised 2188 Japanese individuals, including 593 subjects with coronary artery spasm (453 men, 140 women) and 1595 controls (762 men, 833 women). The genotypes for 35 polymorphisms of 29 candidate genes were determined with an allele-specific DNA primer-probe assay. Multivariable logistic regression analysis adjusted for age, body mass index, and the prevalence of smoking, hypertension, diabetes mellitus, hypercholesterotaemia, and hyperuricaemia revealed a significant association with coronary artery spasm of one polymorphism (242C-->T in the NADH/NADPH oxidase p22 phox gene) in men and two polymorphisms (-1171/5A --> 6A in the stromelysin-1 gene and -634C --> G in the interleukin-6 gene) in women. A stepwise forward selection procedure revealed that smoking was the most important risk factor for coronary artery spasm and that the effects of these potymorphisms on this condition were statistically independent of smoking. Conclusion The NADH/NADPH oxidase p22 phox gene is a susceptibility Locus for coronary artery spasm in men, and the stromelysin-1 and interleukin-6 genes are susceptibility loci in women. (C) 2004 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.
  • H Horibe, Y Yamada, S Ichihara, M Watarai, M Yanase, K Takemoto, S Shimizu, H Izawa, F Takatsu, M Yokota
    ATHEROSCLEROSIS 174 (1) 181 - 187 0021-9150 2004/05 [Refereed][Not invited]
     
    Plain old balloon angioplasty (POBA) is a useful therapeutic strategy especially for angioplasty of small coronary arteries. An association study was performed to identify genes that confer susceptibility to restenosis after POBA. The study population comprised 730 individuals (424 men, 306 women) who underwent successful POBA in at least one major coronary artery and were examined angiographically 6 months after the procedure. A total of 469 subjects (273 men, 196 women) exhibited no restenosis after POBA for any of the coronary lesions, whereas 261 subjects (151 men, 110 women) manifested restenosis for all lesions. The genotypes for 40 polymorphisms of 34 genes were determined with a fluorescence- or colorimetry-based allele-specific DNA primer-probe assay. Multivariate logistic regression analysis with adjustment for age, body mass index, and the prevalence of smoking, hypertension, diabetes mellitus, hypercholesterolemia, and hyperuricemia revealed that two polymorphisms (242C --> T in the NADH/NADPH oxidase p22 phox (p22-PHOX) gene and 2136C --> T in the thrombomodulin (THBD) gene) in men and two polymorphisms (584G --> A in the paraoxonase 1 (PON1) gene and 2445G --> A in the fatty acid-binding protein 2 (FABP2) gene) in women were significantly associated with restenosis after POBA. A stepwise forward selection procedure revealed that the effects of these polymorphisms on restenosis were statistically independent of conventional risk factors for coronary artery disease. Genotyping of these polymorphisms may prove informative for assessment of genetic risk for restenosis after POBA. (C) 2004 Elsevier Ireland Ltd. All rights reserved.
  • Y Yamada, S Ichihara, H Izawa, M Tanaka, M Yokota
    MOLECULAR GENETICS AND METABOLISM 81 (4) 282 - 290 1096-7192 2004/04 [Refereed][Not invited]
     
    Given that a substantial proportion of individuals with coronary artery disease (CAD) also have type 2 diabetes, it is important to identify genes that confer susceptibility to CAD independently in subjects with type 2 diabetes and in those without this condition. A large-scale association study was performed to identify genes that confer susceptibility to CAD in either the absence or presence of type 2 diabetes. The study population comprised 5207 unrelated Japanese individuals, including 3085 subjects with CAD and 2122 controls. Among all subjects, 1704 individuals had type 2 diabetes and 3503 individuals did not have this condition. The genotypes for 33 polymorphisms of 27 candidate genes were determined with a fluorescence- or colorimetry-based allele-specific DNA primer-probe assay system. Multivariate logistic regression analysis with adjustment for age, body mass index, and the prevalence of smoking, hypertension, hypercholesterolemia, and hyperuricemia revealed that the following polymorphisms were significantly (P < 0.005) associated with CAD: the 1019C &RARR; T of the connexin 37 gene for men with type 2 diabetes; the 2445G &RARR; A in the fatty acid-binding protein 2 gene for women with this condition; the -863C &RARR; A in the tumor necrosis factor-α gene, the -219G &RARR; T in the apolipoprotein E gene, the 1019C &RARR; T in the connexin 37 gene for men without type 2 diabetes; and the -482C &RARR; T in the apolipoprotein C-III gene for women without this condition. Genotyping of these polymorphisms may prove informative for assessment of the genetic risk for CAD in the absence or presence of type 2 diabetes. (C) 2004 Elsevier Inc. All rights reserved.
  • K Shimokata, Y Yamada, T Kondo, S Ichihara, H Izawa, K Nagata, T Murohara, M Ohno, M Yokota
    ATHEROSCLEROSIS 172 (1) 167 - 173 0021-9150 2004/01 [Refereed][Not invited]
     
    A substantial proportion of individuals with coronary artery disease (CAD) has concomitant hypercholesterolemia. A large-scale association study was performed to identify separately genes that confer susceptibility to CAD in the absence or presence of nonfamilial hypercholesterolemia. The study population comprised 5248 unrelated Japanese individuals, including 3085 subjects with CAD (2350 men, 735 women) and 2163 controls (1329 men. 834 women). Among all study subjects, 2541 individuals (1688 men, 853 women) had nonfamilial hypercholesterolemia, and 2707 individuals (1991 men, 716 women) did not have this condition. The genotypes for 33 polymorphisms of 27 candidate genes were determined with a fluorescence- or colorimetry-based allele-specific DNA primer-probe assay system. Multivariate logistic regression analysis with adjustment for age, body mass index, and the prevalence of smoking, hypertension, diabetes mellitus, and hyperuricemia revealed that three polymorphisms [994G --> T (Va1279Phe) in the platelet-activating factor acetylhydrolase gene, 242C --> T (His72Tyr) in the NADH/NADPH oxidase p22 phox gene, and 1100C --> T in the apolipoprotein C-III gene] were significantly associated with CAD in men with hypercholesterolemia. Genotyping of these three polymorphisms may prove informative for prediction of the genetic risk for CAD in men with nonfamilial hypercholesterolemia. (C) 2003 Elsevier Ireland Ltd. All rights reserved.
  • K Nagata, K Obata, M Odashima, A Yamada, F Somura, T Nishizawa, S Ichihara, H Izawa, M Iwase, A Hayakawa, T Murohara, M Yokota
    JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY 35 (12) 1505 - 1512 0022-2828 2003/12 [Refereed][Not invited]
     
    The anti-anginal drug nicorandil has been shown to inhibit apoptosis by activating mitochondrial ATP-sensitive potassium (K-ATP) channels. The possible contribution of the nitrate moiety of this drug to its anti-apoptotic effect has now been investigated in neonatal rat ventricular myocytes subjected to oxidative stress. Exposure of cultured myocytes to 100 mumol/l hydrogen peroxide (H2O2) increased the number of nuclei stained by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling technique as well as induced internucleosomal DNA fragmentation, loss of mitochondrial membrane potential, cytochrome c release into the cytosol, and activation of caspases-3 and -9, all of which are characteristics of apoptosis. Pretreatment of cells with nicorandil (100 mumol/l) inhibited these effects of H2O2. Both the mitochondrial K-ATP channel antagonist 5-hydroxydecanoate (5-HD) and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylyl cyclase, attenuated the anti-apoptotic effect of nicorandil in concentration-dependent manners. Coapplication of ODQ (10 mumol/l) and 5-HD (500 mumol/l) completely abolished nicorandil-induced cytoprotection. The effect of nicorandil was also reduced by an inhibitor of cGMP-dependent protein kinase (KT5823, 1 mumol/l). The nitric oxide donor (+/-)-S-nitroso-N-acetylpenicillamine (SNAP, 50 mumol/l) mimicked the protective effect of nicorandil in a manner sensitive to ODQ but not to 5-HD. A cell-permeable cGMP analog, 8-bromo-cGMP. also reduced H2O2-induced apoptosis. The inhibition of the H2O2-induced activation of caspase-3, but not that of caspase-9, by nicorandil in the presence of 5-HD or by SNAP was reversed by the addition of dithiothreitol to the enzyme assay. Nicorandil inhibits oxidative stress-induced apoptosis in cardiac myocytes through a nitric oxide/cGMP-dependent mechanism as well as by activating mitochondrial K-ATP channels. (C) 2003 Elsevier Ltd. All rights reserved.
  • Y Yamada, H Izawa, S Ichihara, F Takatsu, H Ishihara, H Hirayama, T Sone, M Tanaka, M Yokota
    NEW ENGLAND JOURNAL OF MEDICINE 347 (24) 1916 - 1923 0028-4793 2002/12 [Refereed][Not invited]
     
    Background: Although epidemiologic studies have suggested that several genetic variants increase the risk of myocardial infarction, large-scale association studies that examine many polymorphisms simultaneously are required to allow reliable prediction of the genetic risk of myocardial infarction. Methods: We used a fluorescence- or colorimetry-based allele-specific DNA-primer-probe assay system to determine the genotypes of 112 polymorphisms of 71 candidate genes in 2819 unrelated Japanese patients with myocardial infarction (2003 men and 816 women) and 2242 unrelated Japanese controls (1306 men and 936 women). Results: In an initial screening of the 112 polymorphisms for an association with myocardial infarction in 909 subjects, 19 polymorphisms were selected in men and 18 in women by means of logistic-regression analysis, after adjustment for age, body-mass index, and the prevalence of smoking, hypertension, diabetes mellitus, hypercholesterolemia, and hyperuricemia. In a large-scale study involving the selected polymorphisms and the remaining 4152 subjects, similar logistic-regression analysis revealed that the risk of myocardial infarction was significantly associated with the C1019T polymorphism in the connexin 37 gene (P<0.001) in men and the 4G-668/5G polymorphism in the plasminogen-activator inhibitor type 1 gene (P<0.001) and the 5A-1171/6A polymorphism in the stromelysin-1 gene (P<0.001) in women. Conclusions: Determination of the genotypes of the connexin 37, plasminogen-activator inhibitor type 1, and stromelysin-1 genes may prove reliable in predicting the genetic risk of myocardial infarction and might thus contribute to the primary prevention of this condition.
  • S Ichihara, T Senbonmatsu, E Price, T Ichiki, FA Gaffney, T Inagami
    CIRCULATION 106 (17) 2244 - 2249 0009-7322 2002/10 [Refereed][Not invited]
     
    Background-Accumulating evidence has suggested that the cardiac renin-angiotensin system is activated during the remodeling process after myocardial infarction (MI). Although 2 types of angiotensin II receptors (AT(1) and AT(2)) are upregulated in the infarcted tissue, the contribution of AT(2) to the subsequent fibrogenetic phase of wound healing is less certain. This study was conducted to evaluate the role of AT(2) in wound healing after MI using an in vivo intervention study in mice with MI. Methods and Results-We examined myocardial hypertrophy, cardiac fibrosis, and morphological evidence of fibrillar collagen accumulation at the infarcted and noninfarcted regions in male mice lacking the AT(2) receptor (Agtr2-/Y) and age-matched wild-type (WT) animals. Of the Agtr2-/Y mice, 63.6% died of cardiac rupture, whereas 23.5% of the WT mice died of the same cause within 1 week. The extent of fibrosis and that of collagen gene expression in Agtr2-/Y mice were significantly reduced compared with WT mice at 1 week after coronary ligation. Furthermore, MI resulted in a marked increase in the prostaglandin E-2 (PGE(2)) level at 4 days after surgery in Agtr2-/Y mice. In WT mice, the PGE(2) level was also elevated after MI but to a significantly lesser extent than in Agtr2-/Y mice. Conclusions-A chronic loss of AT(2) by gene targeting prevented the collagen deposition and caused cardiac rupture. The markedly elevated PGE(2) may be a mechanism that inhibits collagen synthesis in the infarcted region of Agtr2-/Y mice.
  • K Nagata, F Somura, K Obata, M Odashima, H Izawa, S Ichihara, T Nagasaka, M Iwase, Y Yamada, N Nakashima, M Yokota
    HYPERTENSION 40 (2) 168 - 174 0194-911X 2002/08 [Refereed][Not invited]
     
    The possible role of calcineurin in the attenuation of cardiac hypertrophy and fibrosis by blockade of the angiotensin II type I (AT,) receptor was investigated in Dahl salt-sensitive (DS) rats. The effect of the calcineurin inhibitor FK506 was also studied. DS rats progressively developed severe hypertension when fed a diet containing 8% NaCl from 7 weeks of age. In addition, marked cardiac hypertrophy and fibrosis were apparent and the activity of calcineurin and its mRNA expression in the myocardium was increased in these animals at 12 weeks in comparison with age-matched Dahl salt-resistant rats. The abundance of angiotensin-converting enzyme (ACE) and transforming growth factor (TGF)-beta1 mRNAs was also increased in the hearts of DS rats at 12 weeks. Treatment of DS rats with a non-antihypertensive dose of the selective AT, receptor blocker candesartan (1 mg/kg per day) or FK506 (0.1 mg/kg per day) from 7 to 12 weeks attenuated both calcineurin activity and its mRNA expression in the heart, as well as the development of cardiac hypertrophy and fibrosis, without affecting cardiac function. Treatment with candesartan, but not FK506, prevented the upregulation of ACE and TGF-beta1 gene expression. Both candesartan and FK506 prevented the load-induced induction of fetal-type cardiac genes. These results demonstrate that AT, receptor blockade attenuates the development of cardiac hypertrophy and fibrosis as well as the activation of calcineurin, without an antihypertensive effect, in rats with salt-sensitive hypertension. Calcineurin may be downstream from TGF-beta1 in AT, receptor-mediated angiotensin II signaling in vivo.

Research Grants & Projects

  • 喫煙による循環器系への影響
    共同研究
    Date (from‐to) : 2003 -2007
  • 環境化学物質の心血管系システムへの影響
    共同研究
    Date (from‐to) : 2005
  • メタボリック症候群における心血管障害の機序の解明
    共同研究
    Date (from‐to) : 2004
  • Cardiovascular diseases and oxidative stress


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