Hisamoto Kuroda

Ursodeoxycholic acid inhibits the induction of nitric oxide synthase

Ursodeoxycholic acid was recently recognized as an effective agent in the treatment of primary biliary cirrhosis. Since the beneficial effect of ursodeoxycholic acid therapy appears to be mediated in part by an immune mechanism, we evaluated the effects of ursodeoxycholic acid on the synthesis of nitric oxide (NO), elevated production of which could be important in the pathogenesis of autoimmunity. Ursodeoxycholic acid (0.1-1000 microM) inhibited NO production by bacterial lipopolysaccharide-activated J774 macrophages in a concentration-dependent fashion, but the cytotoxicity was also evident at higher concentrations (250 and 1000 microM). Ursodeoxycholic acid did not have any effect on the activity of NO synthase that had already been induced. Treatment with lipopolysaccharide led to a significant expression of NO synthase mRNA that was significantly reduced by ursodeoxycholic acid. Findings indicated that ursodeoxycholic acid inhibited NO synthesis by inhibiting the induction of NO synthase, rather than its catalytic activity. Ursodeoxycholic acid therapy may exert a beneficial effect, in part, by attenuating the production of NO.

Inhibition by protein kinase-C inhibitor and cycloheximide of phorbol ester- and epidermal growth factor-induced arachidonic acid metabolism in cultured porcine thyroid cells

In an attempt to elucidate possible mechanism(s) for stimulated arachidonic acid metabolism by phorbol 12-myristate 13-acetate (PMA) and epidermal growth factor (EGF) in porcine thyroid cells, we examined the effects of protein kinase inhibitors, isoquinolinesulfonamide derivatives (H-7 and HA-1004), and cycloheximide. The production of PGE2 stimulated by either PMA or EGF was strongly inhibited by H-7, with an ID50 value of approximately 20 to 25 mumol/L in each case, as well as by cycloheximide, with an ID50 value of less than 0.5 micrograms/mL in each case. In contrast, 100 mumol/L of HA-1004 showed less inhibition of PGE2 production provocated by either PMA or EGF. On the other hand, PGE2 production in basal or stimulated condition by exogenously added arachidonic acid, was inhibited to an even lesser extent by both H-7 and cycloheximide. The EGF- and PMA-stimulated release of 3H-arachidonic acid from the cells was also strongly inhibited by H-7 and cycloheximide. These results suggest an induction of synthesis of some proteins responsible for the release of arachidonic acid, which might be attributed to protein kinase-C activation in arachidonic acid metabolism stimulated by PMA or EGF. Moreover, PGE2 production was potently induced by PMA and slightly by EGF in the cyclooxygenase-inactivated cells by acetyl salicylate pretreatment, which also suggests that both agents might induce the synthesis of cyclooxygenase in cultured porcine thyroid cells, although we did not measure its activity.

Fixed-dose combination of alogliptin/pioglitazone improves glycemic control in Japanese patients with type 2 diabetes mellitus independent of body mass index

ABSTRACT This study investigated the effects of switching from combination therapy with either alogliptin (Alo) or pioglitazone (Pio) to fixed-dose combination therapy (FDCT) with alogliptin and pioglitazone (Alo-Pio FDCT). The usefulness and efficacy of Alo-Pio FDCT were investigated. A total of 50 outpatients with type 2 diabetes mellitus (T2DM) treated with Alo and 47 outpatients with T2DM treated with Pio were switched to Alo-Pio FDCT, and its efficacy and usefulness were evaluated. Significant improvements were observed in hemoglobinA1c (HbA1c), alanine transaminase (ALT), and γ-glutamyl transpeptidase (GGT) levels after switching to Alo-Pio FDCT for 16 weeks in both groups. Only the group switching from Alo to Alo-Pio FDCT showed significant improvements in high-density lipoprotein cholesterol (HDL) levels and triglyceride levels. In a multivariate logistic regression model of the variation in the change of HbA1c at 16 weeks, ALT and GGT were independent predictors of the change of HbA1c at 16 weeks. In addition, the switch to Alo-Pio FDCT improved glycemic control to a certain degree regardless of BMI. Switching from either Alo or Pio to Alo-PIO FDCT may, unlike monotherapy with a DPP-4 inhibitor, be effective for patients with T2DM regardless of whether they are obese or lean.