Yuhki Sakuraoka

Dokkyo Medical University, Tochigi, Tochigi-ken, Japan

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Publications (4)11.22 Total impact

  • Article: Analysis of hepcidin expression: in situ hybridization and quantitative polymerase chain reaction from paraffin sections.
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    ABSTRACT: To establish methods for quantitative polymerase chain reaction (PCR) for hepcidin using RNAs isolated from paraffin-embedded sections and in situ hybridization of hepatocellular carcinoma (HCC). Total RNA from paraffin-embedded sections was isolated from 68 paraffin-embedded samples of HCC. Samples came from 54 male and 14 female patients with a mean age of 66.8 ± 7.8 years. Quantitative PCR was performed. Immunohistochemistry and in situ hybridization for hepcidin were also performed. Quantitative PCR for hepcidin using RNAs isolated from paraffin-embedded sections of HCC was performed successfully. The expression level of hepcidin mRNA in cancer tissues was significantly higher than that in non-cancer tissues. A method of in situ hybridization for hepcidin was established successfully, and this demonstrated that hepcidin mRNA was expressed in non-cancerous tissue but absent in cancerous tissue. We have established novel methods for quantitative PCR for hepcidin using RNAs isolated from paraffin-embedded sections and in situ hybridization of HCC.
    World Journal of Gastroenterology 07/2012; 18(28):3727-31. · 2.47 Impact Factor
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    Article: Glycated albumin suppresses glucose-induced insulin secretion by impairing glucose metabolism in rat pancreatic β-cells.
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    ABSTRACT: Glycated albumin (GA) is an Amadori product used as a marker of hyperglycemia. In this study, we investigated the effect of GA on insulin secretion from pancreatic β cells. Islets were collected from male Wistar rats by collagenase digestion. Insulin secretion in the presence of non-glycated human albumin (HA) and GA was measured under three different glucose concentrations, 3 mM (G3), 7 mM (G7), and 15 mM (G15), with various stimulators. Insulin secretion was measured with antagonists of inducible nitric oxide synthetase (iNOS), and the expression of iNOS-mRNA was investigated by real-time PCR. Insulin secretion in the presence of HA and GA was 20.9 ± 3.9 and 21.6 ± 5.5 μU/3 islets/h for G3 (P = 0.920), and 154 ± 9.3 and 126.1 ± 7.3 μU/3 islets/h (P = 0.046), for G15, respectively. High extracellular potassium and 10 mM tolbutamide abrogated the inhibition of insulin secretion by GA. Glyceraldehyde, dihydroxyacetone, methylpyruvate, GLP-1, and forskolin, an activator of adenylate cyclase, did not abrogate the inhibition. Real-time PCR showed that GA did not induce iNOS-mRNA expression. Furthermore, an inhibitor of nitric oxide synthetase, aminoguanidine, and NG-nitro-L-arginine methyl ester did not abrogate the inhibition of insulin secretion. GA suppresses glucose-induced insulin secretion from rat pancreatic β-cells through impairment of intracellular glucose metabolism.
    Nutrition & Metabolism 04/2011; 8:20. · 2.88 Impact Factor
  • Article: MK615 decreases RAGE expression and inhibits TAGE-induced proliferation in hepatocellular carcinoma cells.
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    ABSTRACT: To investigate the proliferative effect of advanced glycation end-products (AGEs) and the role of their cellular receptor (RAGE) on hepatocellular carcinoma (HCC) cells, and the inhibitory effects of MK615, an extract from Japanese apricot, against AGEs were also evaluated. Two HCC cell lines, HuH7 and HepG2, were used. Expression of RAGE was investigated by polymerase chain reaction, Western blotting, and flow cytometry (FACS). The effect of MK615 on RAGE expression was also evaluated by FACS. The proliferative effects of a control (unglycated bovine serum albumin), glucose-derived AGEs (Glc-AGE), and glyceraldehyde-derived AGEs (Glycer-AGE), and the anti-proliferative effect of MK615 against AGEs, were evaluated using MTT assays. Expression of RAGE was confirmed at both the mRNA and protein levels in both HuH7 and HepG2. FACS revealed that the level of RAGE expression was higher in HuH7 than in HepG2. Treatment with 0.1 μg/mL MK615 decreased the expression level of RAGE from 24.3% to 3.7% in HuH7 and from 6.2% to 4.8% in HepG2. The growth indices for the control, Glc-AGE, and Glycer-AGE were 1.06 ± 0.08, 0.99 ± 0.04, and 1.38 ± 0.05, respectively, in HuH7 (P = 0.037), and were 1.03 ± 0.04, 1.04 ± 0.03, and 1.07 ± 0.05, respectively, in HepG2 (P > 0.05). When the cells were cultured simultaneously with Glycer-AGE and MK615, MK615 abrogated the proliferative effect of Glycer-AGE in HuH7. Only Glycer-AGE has a proliferative effect on HuH7, which expresses a higher level of RAGE. MK615 suppresses the proliferative effect of Glycer-AGE on HuH7 by decreasing the expression of RAGE.
    World Journal of Gastroenterology 11/2010; 16(42):5334-41. · 2.47 Impact Factor
  • Article: Renoprotective effect of erythropoietin against ischaemia-reperfusion injury in a non-human primate model.
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    ABSTRACT: The renoprotective effect of erythropoietin (Epo) against ischaemia-reperfusion injury (IR/I) was evaluated in a non-human primate model. Crab-eating macaques were divided into two groups: Control (n = 10), treated with saline, and EPO (n = 10), treated with Epo. Epo was injected intravenously at a dose of 12,000 units, 5 min before clamping the renal pedicle and 5 min before declamping. Renal IR/I was created by clamping the left renal artery for 90 min following right nephrectomy. Haemoglobin (Hb), haematocrit (Ht), creatinine (Cr), blood urea nitrogen (BUN), cystatin C and interleukin-6 (IL-6) were measured before (Pre) and after (Day 0) the operation, and on post-operative days: Day 1, Day 3, Day 5 and Day 7. Apoptotic cells were counted on Day 1. There were no differences in Hb and Ht between the two groups. Cr, BUN, cystatin C and IL-6 levels in the EPO group were lower than those in the Control group at most of the observation points. The number of apoptotic cells in the Control was significantly higher than that of and EPO group. Epo significantly ameliorates renal IR/I in this non-human primate model. Our findings justify the clinical application of Epo, not only for acute renal failure, but also in transplantation.
    Nephrology Dialysis Transplantation 10/2010; 26(4):1157-62. · 3.40 Impact Factor