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| 1.
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Misu, Hirofumi ; Takamura, Toshinari ; Takayama, Hiroaki ; Hayashi, Hiroto ; Matsuzawa-Nagata, Naoto ; Kurita, Seiichiro ; Ishikura, Kazuhide ; Ando, Hitoshi ; Takeshita, Yumie ; Ota, Tsuguhito ; Sakurai, Masaru ; Yamashita, Tatsuya ; Mizukoshi, Eishiro ; Yamashita, Taro ; Honda, Masao ; Miyamoto, Kenichi ; Kubota, Tetsuya ; Kubota, Naoto ; Kadowaki, Takashi ; Kim, Han-Jong ; Lee, In-kyu ; Minokoshi, Yasuhiko ; Saito, Yoshiro ; Takahashi, Kazuhiko ; Yamada, Yoshihiro ; Takakura, Nobuyuki ; Kaneko, Shuichi
概要:
金沢大学医薬保健研究域医学系<br />The liver may regulate glucose homeostasis by modulating the sensitivity/resistance of peripheral ti
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ssues to insulin, by way of the production of secretory proteins, termed hepatokines. Here, we demonstrate that selenoprotein P (SeP), a liver-derived secretory protein, causes insulin resistance. Using serial analysis of gene expression (SAGE) and DNA chip methods, we found that hepatic SeP mRNA levels correlated with insulin resistance in humans. Administration of purified SeP impaired insulin signaling and dysregulated glucose metabolism in both hepatocytes and myocytes. Conversely, both genetic deletion and RNA interference-mediated knockdown of SeP improved systemic insulin sensitivity and glucose tolerance in mice. The metabolic actions of SeP were mediated, at least partly, by inactivation of adenosine monophosphate-activated protein kinase (AMPK). In summary, these results demonstrate a role of SeP in the regulation of glucose metabolism and insulin sensitivity and suggest that SeP may be a therapeutic target for type 2 diabetes. © 2010 Elsevier Inc.
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| 2.
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Nakamura, Seiji ; Takamura, Toshinari ; Matsuzawa-Nagata, Naoto ; Takayama, Hiroaki ; Misu, Hirofumi ; Noda, Hiroyo ; Nabemoto, Satoko ; Kurita, Seiichiro ; Ota, Tsuguhito ; Ando, Hitoshi ; Miyamoto, Kenichi ; Kaneko, Shuichi
概要:
Visceral adiposity in obesity causes excessive free fatty acid (FFA) flux into the liver via the portal vein and may cau
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se fatty liver disease and hepatic insulin resistance. However, because animal models of insulin resistance induced by lipid infusion or a high fat diet are complex and may be accompanied by alterations not restricted to the liver, it is difficult to determine the contribution of FFAs to hepatic insulin resistance. Therefore, we treated H4IIEC3 cells, a rat hepatocyte cell line, with a monounsaturated fatty acid (oleate) and a saturated fatty acid (palmitate) to investigate the direct and initial effects of FFAs on hepatocytes. We show that palmitate, but not oleate, inhibited insulin-stimulated tyrosine phosphorylation of insulin receptor substrate 2 and serine phosphorylation of Akt, through c-Jun NH2-terminal kinase (JNK) activation. Among the well established stimuli for JNK activation, reactive oxygen species (ROS) played a causal role in palmitate-induced JNK activation. In addition, etomoxir, an inhibitor of carnitine palmitoyltransferase-1, which is the rate-limiting enzyme in mitochondrial fatty acid β-oxidation, as well as inhibitors of the mitochondrial respiratory chain complex (thenoyltrifluoroacetone and carbonyl cyanide m-chlorophenylhydrazone) decreased palmitate-induced ROS production. Together, our findings in hepatocytes indicate that palmitate inhibited insulin signal transduction through JNK activation and that accelerated β-oxidation of palmitate caused excess electron flux in the mitochondrial respiratory chain, resulting in increased ROS generation. Thus, mitochondria-derived ROS induced by palmitate may be major contributors to JNK activation and cellular insulin resistance. © 2009 by The American Society for Biochemistry and Molecular Biology, Inc.
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| 3.
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Uno, Masafumi ; Kurita, Seiichiro ; Misu, Hirofumi ; Ando, Hitoshi ; Ota, Tsuguhito ; Matsuzawa-Nagata, Naoto ; Kita, Yuki ; Nabemoto, Satoko ; Akahori, Hiroshi ; Zen, Yoh ; Nakanuma, Yasuni ; Kaneko, Shuichi ; Takamura, Toshinari
概要:
金沢大学医薬保健研究域医学系<br />Nonalcoholic steatohepatitis (NASH) is the progressive form of nonalcoholic fatty liver disease and
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is one of the most common liver diseases in the developed world. The histological findings of NASH are characterized by hepatic steatosis, inflammation, and fibrosis. However, an optimal treatment for NASH has not been established. Tranilast, N-(3′,4′-dimedioxycinnamoyl)- anthranilic acid, is an antifibrogenic agent that inhibits the action of transforming growth factor beta (TGF-β). This drug is used clinically for fibrogenesis-associated skin disorders including hypertrophic scars and scleroderma. TGF-β plays a central role in the development of hepatic fibrosis, and tranilast may thus ameliorate the pathogenesis of NASH. We investigated the effects of tranilast using an established dietary animal model of NASH, obese diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats and nondiabetic control Long-Evans Tokushima Otsuka (LETO) rats fed a methionine-deficient and choline-deficient diet. Treatment with 2% tranilast (420 mg/kg/day) for 8 weeks prevented the development of hepatic fibrosis and the activation of stellate cells, and down-regulated the expression of genes for TGF-β and TGF-β-target molecules, including α1 procollagen and plasminogen activator-1. In addition, tranilast attenuated hepatic inflammation and Kupffer cell recruitment, and down-regulated the expression of tumor necrosis factor alpha. Unexpectedly, tranilast ameliorated hepatic steatosis and up-regulated the expression of genes involved in beta-oxidation, such as peroxisome proliferator-activated receptor α and carnitine O-palmitoyltransferase-1. Most of these effects were observed in LETO rats and OLETF rats, which suggest that the action of tranilast is mediated through the insulin resistance-independent pathway. Conclusion: Our findings suggest that targeting TGF-β with tranilast represents a new mode of therapy for NASH. Copyright © 2008 by the American Association for the Study of Liver Diseases.
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Ando, Hitoshi ; Takamura, Toshinari ; Matsuzawa-Nagata, Naoto ; Shima, Kosuke R. ; Nakamura, Seiji ; Kumazaki, Masafumi ; Kurita, Seiichiro ; Misu, Hirofumi ; Togawa, Naoyuki ; Fukushima, Tatsunobu ; Fujimura, Akio ; Kaneko, Shuichi
概要:
金沢大学医薬保健研究域医学系<br />Recent studies have correlated metabolic diseases, such as metabolic syndrome and non-alcoholic fatt
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y liver disease, with the circadian clock. However, whether such metabolic changes per se affect the circadian clock remains controversial. To address this, we investigated the daily mRNA expression profiles of clock genes in the liver of a dietary mouse model of non-alcoholic steatohepatitis (NASH) using a custom-made, high-precision DNA chip. C57BL/6J mice fed an atherogenic diet for 5 weeks developed hypercholesterolemia, oxidative stress, and NASH. DNA chip analyses revealed that the atherogenic diet had a great influence on the mRNA expression of a wide range of genes linked to mitochondrial energy production, redox regulation, and carbohydrate and lipid metabolism. However, the rhythmic mRNA expression of the clock genes in the liver remained intact. Most of the circadianly expressed genes also showed 24-h rhythmicity. These findings suggest that the biological clock is protected against such a metabolic derangement as NASH. © 2009 Elsevier Inc. All rights reserved.
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| 5.
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Kurita, Seiichiro ; Takamura, Toshinari ; Ota, Tsuguhito ; Matsuzawa-Nagata, Naoto ; Kita, Yuki ; Uno, Masafumi ; Nabemoto, Satoko ; Ishikura, Kazuhide ; Misu, Hirofumi ; Ando, Hitoshi ; Zen, Yoh ; Nakanuma, Yasuni ; Kaneko, Shuichi
概要:
金沢大学大学院医学系研究科<br />金沢大学医薬保健研究域医学系<br />Insulin resistance is a major pathological condition associated with obesity and
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metabolic syndrome. Insulin resistance and the renin-angiotensin system are intimately linked. We evaluated the role of the renin-angiotensin system in the pathogenesis of insulin resistance-associated, non-alcoholic steatohepatitis by using the angiotensin II type 1 receptor blocker olmesartan medoxomil in a diabetic rat model. The effects of olmesartan on methionine- and choline-deficient (MCD) diet-induced steatohepatitis were investigated in obese, diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats and control Long-Evans Tokushima Otsuka (LETO) rats. Components of the renin-angiotensin system were up-regulated in the livers of OLETF rats, compared with LETO rats. In OLETF, but not LETO, rats, oral administration of olmesartan for 8 weeks ameliorated insulin resistance. Moreover, olmesartan suppressed MCD diet-induced hepatic steatosis and the hepatic expression of lipogenic genes (sterol regulatory element-binding protein-1c and fatty acid synthase) in OLETF, but not LETO, rats. In both OLETF and LETO rats, olmesartan inhibited hepatic oxidative stress (4-hydroxy-2-nonenal-modified protein) and expression of NADPH oxidase. Olmesartan also inhibited hepatic fibrosis, stellate cell activation, and expression of fibrogenic genes (transforming growth factor-β, α1 [I] procollagen, plasminogen activator inhibitor-1) in both OLETF and LETO rats. In conclusion, pharmacological blockade of the angiotensin II type 1 receptor slows the development of steatohepatitis in the OLETF rat model. This angiotensin II type 1 receptor blocker may exert insulin resistance-associated effects against hepatic steatosis and inflammation as well as direct effects against the generation of reactive oxygen species and fibrogenesis. © 2008 Elsevier B.V. All rights reserved.
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Matsuzawa-Nagata, Naoto ; Takamura, Toshinari ; Ando, Hitoshi ; Nakamura, Seiji ; Kurita, Seiichiro ; Misu, Hirofumi ; Ota, Tsuguhito ; Yokoyama, Masayoshi ; Honda, Masao ; Miyamoto, Ken-ichi ; Kaneko, Shuichi
概要:
金沢大学医薬保健研究域医学系<br />Insulin resistance is a key pathophysiological feature of metabolic syndrome. However, the initial e
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vents triggering the development of insulin resistance and its causal relations with dysregulation of glucose and fatty acids metabolism remain unclear. We investigated biological pathways that have the potential to induce insulin resistance in mice fed a high-fat diet (HFD). We demonstrate that the pathways for reactive oxygen species (ROS) production and oxidative stress are coordinately up-regulated in both the liver and adipose tissue of mice fed an HFD before the onset of insulin resistance through discrete mechanism. In the liver, an HFD up-regulated genes involved in sterol regulatory element binding protein 1c-related fatty acid synthesis and peroxisome proliferator-activated receptor α-related fatty acid oxidation. In the adipose tissue, however, the HFD down-regulated genes involved in fatty acid synthesis and up-regulated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex. Furthermore, increased ROS production preceded the elevation of tumor necrosis factor-α and free fatty acids in the plasma and liver. The ROS may be an initial key event triggering HFD-induced insulin resistance. © 2008 Elsevier Inc. All rights reserved.
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| 7.
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Ando, Hitoshi ; Kurita, Seiichiro ; Shimizu, Akiko ; Kato, Ken-ichiro ; Ishikura, Kazuhide ; Taji, Koumei ; Uno, Masafumi ; Takeshita, Yumie ; Misu, Hirofumi ; Fujimura, Akio ; Kaneko, Shuichi ; Takamura, Toshinari
概要:
Few studies have evaluated the pharmacokinetics of rapid-acting insulin analogues in patients with Type 2 diabetes, espe
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cially under clinical conditions. The aim of the present study was to assess both the pharmacokinetics and pharmacodynamics of insulin aspart in Type 2 diabetic patients who were being treated with the analogue alone. Meal tolerance tests with and without self-injection of a customary dose of insulin aspart (0.05-0.22 U/kg) were conducted in 20 patients in a randomized cross-over study. The dose of insulin aspart (per bodyweight) was significantly correlated with both the maximum concentration (r 2 = 0.59; P < 0.01) and area under the concentration-time curve for insulin aspart (r 2 = 0.53; P < 0.01). However, the time to maximum concentration (T max), which varied widely from < 60 to ≥ 120 min, was not associated with either dosage (r 2 = 0.02; P = 0.51) or body mass index (r 2 = 0.02; P = 0.57). Injection of insulin aspart exacerbated delayed hyperinsulinaemia after meal loading, mainly in patients with T max ≥ 120 min. With regard to pharmacodynamics, insulin aspart had favourable effects on postprandial hyperglycaemia, hyperglucagonaemia and hyperlipidaemia. The T max for this insulin analogue differed greatly between individuals and delayed hyperinsulinaemia was particularly exacerbated in patients with higher T max values. Identification of the factors contributing to interindividual variation in the absorption lag time is essential for improving the efficacy and safety of insulin aspart. © 2012 The Authors. Clinical and Experimental Pharmacology and Physiology © 2012 Blackwell Publishing Asia Pty Ltd.
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| 8.
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Takeshita, Yumie ; Takamura, Toshinari ; Minato, Hiroshi ; Misu, Hirofumi ; Ando, Hitoshi ; Yamashita, Tatsuya ; Ikeda, Hiroko ; Nakanuma, Yasuni ; Kaneko, Shuichi
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金沢大学医薬保健研究域医学系<br />金沢大学医薬保健研究域医学系恒常性制御学<br />Multiple liver metastases were incidentally detected in the lobe of the li
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ver of an 81-year-old woman following total thyroidectomy and ablative radioactive iodine administration for the treatment of papillary thyroid carcinoma. A biopsy specimen taken from the metastatic liver tumor was histologically diagnosed as anaplastic carcinoma. Immunohistochemical staining for p53 was positive in both the primary tumor and liver biopsy specimens. We considered this to have been caused by anaplastic transformation from papillary thyroid carcinoma during treatment. We report a rare case of multiple liver metastases from a papillary thyroid carcinoma, which we believe to be the result of anaplastic transformation during postoperative radioactive iodine-131 therapy. © 2008 The Japanese Society of Internal Medicine.
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| 9.
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Kita, Yuki ; Takamura, Toshinari ; Misu, Hirofumi ; Ota, Tsuguhito ; Kurita, Seiichiro ; Takeshita, Yumie ; Uno, Masafumi ; Matsuzawa-Nagata, Naoto ; Kato, Ken-ichiro ; Ando, Hitoshi ; Fujimura, Akio ; Hayashi, Koji ; Kimura, Toru ; Ni, Yinhua ; Otoda, Toshiki ; Miyamoto, Ken-ichi ; Zen, Yoh ; Nakanuma, Yasuni ; Kaneko, Shuichi
概要:
Background: Optimal treatment for nonalcoholic steatohepatitis (NASH) has not yet been established, particularly for ind
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ividuals without diabetes. We examined the effects of metformin, commonly used to treat patients with type 2 diabetes, on liver pathology in a non-diabetic NASH mouse model. Methodology/Principal Findings: Eight-week-old C57BL/6 mice were fed a methionine- and choline-deficient plus high fat (MCD+HF) diet with or without 0.1% metformin for 8 weeks. Co-administration of metformin significantly decreased fasting plasma glucose levels, but did not affect glucose tolerance or peripheral insulin sensitivity. Metformin ameliorated MCD+HF diet-induced hepatic steatosis, inflammation, and fibrosis. Furthermore, metformin significantly reversed hepatic steatosis and inflammation when administered after the development of experimental NASH. Conclusions/Significance: These histological changes were accompanied by reduced hepatic triglyceride content, suppressed hepatic stellate cell activation, and the downregulation of genes involved in fatty acid metabolism, inflammation, and fibrogenesis. Metformin prevented and reversed steatosis and inflammation of NASH in an experimental non-diabetic model without affecting peripheral insulin resistance. © 2012 Kita et al.
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| 10.
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Takeshita, Yumie ; Takamura, Toshinari ; Kita, Yuki ; Ando, Hitoshi ; Ueda, Teruyuki ; Kato, Kenichiro ; Misu, Hirofumi ; Sunagozaka, Hajime ; Sakai, Yoshio ; Yamashita, Tatsuya ; Mizukoshi, Eishiro ; Honda, Masao ; Kaneko, Shuichi
概要:
Branched-chain amino acids (BCAAs) improve disorders of albumin metabolism, quality of life, subjective symptoms, and pr
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ognosis in patients with chronic hepatitis. However, it remains unclear whether they improve insulin resistance. We examined the effects of BCAAs on glucose tolerance and insulin sensitivity in patients with chronic hepatitis C and insulin resistance. Individuals with a definitive diagnosis of chronic hepatitis C and insulin resistance were eligible for participation. Eligible participants were randomly assigned to the BCAA group or a control group. Participants were then crossed over to the other treatment for a further 12 weeks. Baseline clinical features, laboratory markers, fatty acid levels, and insulin sensitivity, assessed with oral glucose tolerance tests and a hyperinsulinemic euglycemic clamp, were also examined before and 12 and 24 weeks after the beginning of the study. Of the 27 patients who completed the study, 14 began in the BCAA group and 13 began as controls. There were no significant differences in glucose metabolism parameters or lipid profiles between the groups. HbA1c values were improved in 10 patients and worsened or remained unchanged in 17 patients. The only predictive variable for change in HbA1c was the baseline Matsuda index: the lower the index, the greater the improvement in HbA1c values. BCAA therapy did not have adverse effects on glucose tolerance or insulin sensitivity in patients with chronic hepatitis C and insulin resistance. Moreover, it had a therapeutic effect on HbA1c values in patients with marked peripheral (primarily muscle) insulin resistance. © 2012 Elsevier Inc.
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