Life style-related diseases are associated with an increased risk of colorectal cancer (CRC). Recently, an association has been demonstrated between obesity and CRC. CRC has been associated with markers of insulin or glucose control, and insulin resistance might be the unifying mechanism by which several risk factors affect colorectal carcinogenesis. We evaluated the association between the number of aberrant crypt foci (ACF) and obesity, insulin resistance, hyperlipidemia, and other factors of life style-related disease. As a result, age, body mass index (BMI), waist circumference, and visceral fat obesity were significantly associated with the number of ACF. These results suggest that visceral fat obesity is an important target for CRC prevention. Peroxisome proliferator-activated receptor gamma (PPARγ) is a member of the nuclear receptor superfamily and is highly expressed in CRC. PPARγ ligand administration for 1 to 8 months significantly reduced the number of ACF in human subjects. PPARγ ligand is a promising candidate as a chemopreventive agent. Further investigation is needed to elucidate these mechanisms.

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Many reports indicated that endocrine disruptors (EDs) affect several hormonal functions in various living things. Here, we show the effect of EDs on lipid accumulation in target cells involved in the onset of metabolic syndrome. Treatment with nonylphenol and bisphenol A, typical EDs, stimulated the accumulation of triacylglycerol in differentiated adipocytes from 3T3-L1, preadipocytes, in time- and concentration-dependent manners. Up-regulation of gene expressions involved in lipid metabolism and metabolic syndrome were observed in adipocytes treated with EDs. Similarly, stimulatory effects of EDs were also observed on the human hepatoma cell line HuH-7. These observations indicate that exposure to EDs stimulates the lipid accumulation in target cells involved in the metabolic syndrome and may cause the dysfunction of those cells, resulting in induction of metabolic syndrome.

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The hepatitis C virus (HCV) is an enveloped virus with a single positive-strand RNA genome of about 9.6 kb. It is a major cause of liver disease worldwide. Clear understanding of the viral life cycle has been hampered by the lack of a robust cell culture system. While the development of the HCV replicon system was a major breakthrough, infectious virions could not be produced with the replicon system. Recently, several groups have reported producing HCV virions using in vitro systems. One of these is a replicon system, but with the special genotype 2a strain JFH-1. Another is a DNA transfection system, with the construct containing the cDNA of the known infectious HCV genotype 1b flanked by two ribozymes. The development of these models further extends the repertoire of tools available for the study of HCV biology, and in particular, they may help to elucidate the molecular details of hepatitis C viral assembly and release. This review discusses the progression of experimental strategies related to HCV and how these strategies may be applied to clinical medicine.

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Hepatitis C virus (HCV) infection causes chronic hepatitis and leads to liver fibrosis and hepatocellular carcinoma. Pegylated-interferon and ribavirin is the current standard therapy for chronic hepatitis C. However, the therapy is only effective in 50% of the patients. To overcome this problem, we recently developed the HCV cell culture system (OR6 system) for the screening of anti-HCV reagents. In this OR6 system, the luciferase gene was introduced into the upstream portion of the HCV genome to facilitate the monitoring of HCV RNA replication. Recently lipid metabolism is reported to be involved in HCV RNA replication. Cholesterol and sphingolipid are the major components in lipid rafts, which seem to be the scaffold for HCV RNA replication. Statins inhibit cholesterol biosynthesis and also have the pleiotropic effects by the inhibition of prenylation. We demonstrated different anti-HCV effects of statins (atorvastatin, simvastatin, fluvastatin, lovastatin, and pitavastatin) using the OR6 system. Surprisingly, in contrast to the other statins, pravastatin exhibited no anti-HCV effect. Furthermore, statins enhanced the anti-HCV effect of interferon in combination. Statins may be a promising candidate for the adjuvant in interferon therapy and may improve the efficiency of the current interferon and ribavirin therapy.

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Nonalcoholic steatohepatitis (NASH) is a subset of nonalcoholic fatty liver disease (NAFLD) and sometimes progresses to cirrhosis and liver failure. We analyzed the expression profiles of approximately 50,000 genes and biological pathways in NASH patients in comparison with simple steatosis patients by using the analytical technique of GSEA (Gene Set Enrichment Analysis) by DNA microarrays. Although expressions of various genes were altered, GSEA showed clearly lower expression of nuclear receptors, including the peroxisome proliferator-activated receptor gamma (PPARγ) pathway. In a preliminary study we therefore investigated the therapeutic effect of low-dose pioglitazone (15 mg/day per body for 24 weeks), a synthetic ligand for PPARγ, in 12 NASH patients. A decrease in aminotransferase (ALT) values to within the normal range was observed in 7 (58.3%) of the patients, and because the dose of pioglitazone was lower than that ordinarily used, no side effects, such as fatigue, lower extremity edema, or weight gain, were observed. In conclusion, the results confirmed involvement of the PPARγ pathway in NASH and the therapeutic utility of a PPARγ ligand.

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We examined oxidative stress and metabolic characteristics of the spontaneously hypertensive hyperlipidemic rat (SHHR) when it was fed a high-fat diet and sucrose solution (HFDS) after N^G-nitro-L-arginine methyl ester ingestion to develop a rat model of metabolic syndrome. This study was carried out to assess the effects of pioglitazone on levels of lipid peroxide (LPO), Cu,Zn superoxide dismutase (Cu,Zn-SOD), catalase (CAT), glutathione peroxidase (GPx), and non-esterified fatty acids (NEFA) in the plasma and liver tissue in HFDS-SHHR compared with Sprague-Dawley rats (SD). In the HFDS-treated groups, levels of LPO, CAT, GPx, and NEFA were elevated and levels of Cu,Zn-SOD were reduced in the plasma and liver tissue, with a marked accumulation of visceral fat. The changes induced by HFDS feeding were severe in the SHHR model that had essential hypertension and hyperlipidemia, when compared with SD that did not have these essential risk factors. Subcutaneous injection of 10 mg/kg per day of pioglitazone for 2 months significantly restored levels of LPO, CAT, GPx, Cu,Zn-SOD, and NEFA in the HFDS-SHHR group, and visceral fat accumulation was reduced. These results suggest that HFDS-SHHR is a suitable model of metabolic syndrome and that pioglitazone treatment can improve oxidative dysregulation in this rat model.

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Angiotensin II (AII) has been reported to induce leukocyte adhesion to endothelium through up-regulation of P-selectin surface expression. However, the underlying molecular and cellular mechanisms remain unknown. P-selectin is stored in Weibel-Palade bodies (WPBs), large secretory granules, in endothelial cells. In this study, we examined the role of protein kinase D (PKD), a newly identified regulator of protein transport, in AII-induced WPB exocytosis and the resultant P-selectin surface expression. We demonstrated that PKD2 was rapidly activated by AII in endothelial cells through phosphorylation of the activation loop at Ser744/748. AII-induced PKD2 activation correlated with increased P-selectin surface expression. Furthermore, AII-regulated PKD2 activation is protein kinase C (PKC) α-dependent. Importantly, knock-down of either PKD2 or PKCα expression inhibited AII-mediated P-selectin surface expression and monocyte adhesion. Our findings provide the first evidence that stimulation of P-selectin surface expression via PKCα-dependent PKD2 activation could be an important mechanism in the early onset of AII-initiated endothelial adhesiveness.

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As functional changes in L-type high voltage-gated calcium channels (HVCCs) are recognized to be one of the major neurochemical modifications occurring in brains of animals with morphine physical dependence, this study attempts to examine whether regional difference in the expressions of HVCC subunits are produced in the brains under such pathological conditions. Scatchard analysis of [³H]PN200-110 binding showed increased Bmax values in the cerebral cortex and the mesolimbic region including the nucleus accumbence, which are brain regions participating in the development of morphine physical dependence, but not in the cerebellum. In the former two brain regions, α1C and α1D subunits of L-type HVCCs and α2/δ1 subunit increased, although decreases of α1B and α2/δ1 subunits were observed in the cerebellum. A single dose of morphine did not change the expression of any of the HVCC subunits. These results indicate that the increased L-type HVCC subunits in the cerebral cortex and mesolimbic region participate in the development of morphine physical dependence.

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Activation of muscarinic acetylcholine receptors (mAChR) is one of the most important signal transduction pathways in the human body. In this study, we investigated the role of mAChR activation in relation to its subtypes in human retinoblastoma cell-lines (WERI-Rb-1) using Ca²⁺ measurement, real-time PCR, and Western Blot techniques. Acetylcholine (ACh) produced prominent [Ca²⁺]_i transients in a repeated manner in WERI-Rb-1 cells. The maximal amplitude of the [Ca²⁺]_i transient was almost completely suppressed by 97.3 ± 0.8% after atropine (1 μM) pretreatment. Similar suppressions were noted after pretreatments with thapsigargin (1 μM), an ER Ca²⁺-ATPase (SERCA) inhibitor, whereas the ACh-induced [Ca²⁺]_i transient was not affected even in the absence of extracellular calcium. U-73122 (1 μM), a PLC inhibitor, and xestospongin C (2 μM), an IP₃-receptor antagonist, elicited 11.5 ± 2.9% and 17.8 ± 1.9% suppressions, respectively. The 50% inhibitory concentration of (IC₅₀) values for blockade of a 100 μM ACh response by pirenzepine and 4-DAMP were 315.8 and 9.1 nM, respectively. Moreover, both M₃ and M₅ mAChRs were prominent in quantitative real-time-PCR. Taken together, the M₃/M₅ subtypes appear to be the major contributor, leading to intracellular calcium mobilization from the internal store via an IP₃-dependent pathway in the undifferentiated retinoblastoma cells.

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NQ12, an antithrombotic agent, has been reported to display a potent antiplatelet activity. This study was undertaken to reveal the effect of NQ12 on rabbit platelet aggregation and signal transduction involved in the arachidonic acid (AA) cascade. NQ12 concentration-dependently suppressed collagen-, AA-, and U46619-induced rabbit platelet aggregation, with IC₅₀ values of 0.71 ± 0.2, 0.82 ± 0.3, and 0.45 ± 0.1 μM, respectively. In addition, the concentration-response curve of U46619 was shifted to the right after NQ12 treatment, indicating an antagonism on thromboxane (TX) A₂ receptors. The collagen-stimulated AA liberation was inhibited by NQ12 in the same pattern as its inhibition of platelet aggregation. Further study revealed that NQ12 potently suppressed AA-mediated TXA₂ formation, but had no effect on the PGD₂ production, indicating an inhibitory effect on TXA₂ synthase, which was supported by a TXA₂ synthase activity assay indicating that NQ12 concentration-dependently inhibited TXA₂ formation converted from PGH₂. On the other hand, the AA-stimulated 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) formation was also suppressed by NQ12. Taken together, these results suggest that NQ12 has a potential to inhibit TXA₂ synthase activity and TXA₂ receptors, and it can modulate AA liberation as well as 12-HETE formation in platelets. This may be a convincing mechanism for the antithrombotic action of NQ12.

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In a mouse model of α-Fas-induced acute liver injury, the orally-administered caspase inhibitor PF-03491390 (formerly named IDN-6556) was retained in the liver for prolonged periods with a low systemic exposure. Reductions in the elevated plasma levels of alanine aminotransferase (ALT) revealed that the retention of PF-03491390 in the liver exerted a hepatoprotective effect, even when pre-administered to mice 4 h before α-Fas insult. Prolonged retention of PF-03491390 in the liver after oral administration has the benefit of low systemic exposure, making this a beneficial agent for the treatment of liver diseases.

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The blocking effect of three 5-HT₄ agonists, cisapride, mosapride, and the newly discovered CJ-033466 on the human ether-a-go-go-related gene (hERG) channel was studied using a whole cell patch-clamp technique in HEK293 cells. Cisapride was found to be the most potent of the hERG blockers. CJ-033466 had the widest safety margin between its hERG blocking activity and 5-HT₄ agonism among the tested compounds. This suggests a lower clinical risk of cardiac arrhythmia in CJ-033466 compared with the other 2 agonists. Therefore, CJ-033466 has the potential to be a drug with higher therapeutic efficacy and less cardiac risk than both cisapride and mosapride.

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We investigated the involvement of γ-aminobutyric acid_A (GABA_A) receptors in the neuroprotective effect of γ-glutamylethylamide (theanine), a component of Japanese green tea, following a 4-h middle cerebral artery (MCA) occlusion in mice. Theanine (1 mg/kg) reduced the size of the cerebral infarct and alterations of NeuN, GFAP, and Iba 1 expression levels at 24 h after MCA occlusion. This neuroprotective effect of theanine was prevented by bicuculline (GABA_A-receptor antagonist, 10 mg/kg) but not 3-mercaptopropionic acid (glutamate decarboxylase inhibitor). These results suggest that the neuroprotective effect of theanine is mediated, at least in part, by GABA_A receptors.

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