Toshiyuki Mizuno

A Combination Therapy With Simvastatin and Ursodeoxycholic Acid Is More Effective for Cholesterol Gallstone Dissolution Than Is Ursodeoxycholic Acid Monotherapy

Inhibitors of 3-hydroxy,3-methylglutaryl coenzyme A (HMG-CoA) reductase have been reported to decrease the cholesterol saturation index (CSI) in duodenal bile in humans and to prevent formation of cholesterol gallstones in animal studies. We performed a prospective study to evaluate the role of HMG-CoA reductase inhibitors as gallstone-dissolving agents. Fifty patients with radiolucent gallstones in a gallbladder opacifying at drip infusion cholecystography were treated with either 10 mg/day simvastatin plus 600 mg/day ursodeoxycholic acid (group 1, n=26) or 600 mg/day ursodeoxycholic acid alone (group 2, n=24) for 12 months. The ratio of solitary to multiple gallstone cases was 21:29. Plasma lipid levels were assessed and ultrasonographic examination of the gallbladder was performed at baseline and at 3-month intervals during treatment. Duodenal bile sampling was performed in five patients in each group at baseline and after 12 months of treatment. Plasma cholesterol decreased significantly in group 1 but not in group 2. In solitary gallstone cases, no significant difference in dissolution rates was observed between groups 1 (3 of 9, 33%) and 2 (4 of 12, 33%). In contrast, the dissolution rate in multiple gallstone cases was significantly higher in group 1 (12 of 17, 71%) than in group 2 (3 of 12, 25%) (p < 0.01). Bile cholesterol saturation index was significantly decreased (p < 0.01) but did not significantly differ between the two groups. These results suggest that combination therapy with simvastatin and ursodeoxycholic acid is more effective for cholesterol gallstone dissolution than ursodeoxycholic acid monotherapy in patients with multiple gallstones.

Overexpression/enhanced kinase activity of BCR/ABL and altered expression of Notch1 induced acute leukemia in p210BCR/ABL transgenic mice

Chronic myelogenous leukemia (CML) is a hematopoietic disorder, which begins as indolent chronic phase but inevitably progresses to fatal blast crisis. p210BCR/ABL, a constitutively active tyrosine kinase, is responsible for disease initiation but molecular mechanism(s) underlying disease evolution remains largely unknown. To explore this process, we employed retroviral insertional mutagenesis to CML-exhibiting p210BCR/ABL transgenic mice (Tg). Virus infection induced acute lymphoblastic leukemia (ALL) in p210BCR/ABL Tg with a higher frequency and in a shorter latency than wild-type littermates, and inverse PCR detected two retrovirus common integration sites (CISs) in p210BCR/ABL Tg tumors. Interestingly, one CIS was the transgene itself, where retrovirus integrations induced upregulation of p210BCR/ABL and production of truncated BCR/ABL with an enhanced kinase activity. Another CIS was Notch1 gene, where retrovirus integrations resulted in overexpression of Notch1 and generation of Notch1 lacking the C-terminal region (Notch1ΔC) associated with stable expression of its activated product, C-terminal-truncated Notch intracellular domain (NICDΔC). In addition, generation of Tg for both p210BCR/ABL and Notch1ΔC developed ALL in a shortened period with Stat5 activation, demonstrating the cooperative oncogenicity of Notch1ΔC/NICDΔC with p210BCR/ABL involving Stat5-mediated pathway. These results demonstrated that overexpression/enhanced kinase activity of BCR/ABL and altered expression of Notch1 induces acute leukemia in a transgenic model for CML.

Oxidative stress reaction in the meniscus of Bach 1 deficient mice: Potential prevention of meniscal degeneration

Bach 1 is a transcription factor that negatively regulates the transcription of heme oxygenase‐1 (HO‐1), a stress‐responding protein. In this study, we investigated the reaction to oxidative stress in the meniscus of Bach 1 deficient mice, and the suppression of meniscal degeneration by the induction of HO‐1. We carried out a comparative study between Bach 1 deficient mice and wild type mice, in which the oxidative stress reaction and age‐related changes were investigated using the menisci of 6‐, 12‐, and 24‐week‐old mice. The degrees of meniscal degeneration and expression of HO‐1 were evaluated using the menisci cultured under oxidative stress with cadmium chloride or interleukin‐1 β. The age‐related changes in the meniscus were histologically examined. The expression of HO‐1 was higher, and the degrees of histological degeneration were lower in the Bach 1 deficient mice than in wild type mice (HO‐1 mRNA expression: In both the Cd group and the IL group, two–fourfold higher in the meniscus). The age‐related changes were lower in the Bach 1 deficient mice than in wild type mice. In 24‐week‐old mice, a moderate decrease in the cell density and proteoglycan content was observed in wild type mice compared with Bach 1 deficient mice. In the menisci of Bach 1 deficient mice, the anti‐oxidative stress activity was considered to be increased by abrogating the suppression of HO‐1 expression, resulting in a reduction of histological degeneration. This finding showed a potential new strategy for the prevention and treatment of meniscal degeneration.

Effects of long-term treatment with low-dose pravastatin on biliary lipid and bile acid composition in patients with nonfamilial hyperlipoproteinemia

We tested the possibility that pravastatin, a competitive inhibitor of hepatic hydroxymethyl glutaryl coenzyme A (HMG CoA) reductase, would alter cholesterol saturation of gallbladder bile by decreasing its cholesterol saturation index and/or degree of fatty acyl chain unsaturation in lecithin. Eighteen patients with type IIa hyperlipoproteinemia were treated with pravastatin 10 mg/d for 12 months. Gallbladder bile samples were aspirated with a duodenal tube by stimulating gallbladder contraction with intramuscular administration of cerulein before and after treatment. Serum cholesterol level was significantly reduced by 20% after 3 months, and this level was maintained after 12 months. In contrast, the cholesterol saturation index of gallbladder bile was not altered after 3 months (1.52 +/- 0.20 v 1.70 +/- 0.24), but it decreased significantly after 12 months (0.95 +/- 0.11, P < .01). The degree of fatty acyl chain unsaturation tended to decrease, although this was not statistically significant except for the decrease in molar percent of linoleate after 3 months. These findings suggest that long-term treatment with an inhibitor of HMG CoA reductase improves bile lithogenicity even at a comparatively low dose, and can decrease the incidence and complications of cholesterol gallstones.

Modulation of the secondary injury process after spinal cord injury in Bach1-deficient mice by heme oxygenase-1

OBJECT Oxidative stress contributes to secondary injury after spinal cord injury (SCI). The expression of heme oxygenase-1 (HO-1), which protects cells from various insults including oxidative stress, is upregulated in injured spinal cords. Mice deficient in Bach1 (Bach1-/-), a transcriptional repressor of the HO-1 and beta-globin genes, express high levels of HO-1 mRNA and protein in various organs. The authors hypothesized that HO-1 modulates the secondary injury process after SCI in Bach1(-/-) mice. METHODS Male C57BL/6 (wild-type) and homozygous Bach1(-/-) C57BL/6 mice were subjected to moderate SCI, and differences in hindlimb motor function, and electrophysiological, molecular biological, and histopathological changes were assessed for 2 weeks. RESULTS Functional recovery was greater, and motor evoked potentials were significantly larger in Bach1(-/-) mice than in wild-type mice throughout the observation period. The expression of HO-1 mRNA in the spinal cord was significantly increased in both mice until 3 days after injury, and it was significantly higher in Bach1(-/-) mice than in wild-type mice at every assessment point. Histological examination using Luxol fast blue staining at 1 day after injury showed that the injured areas were smaller in Bach1(-/-) mice than in wild-type mice. The HO-1 immunoreactivity was not detected in uninjured spinal cord, but 3 days postinjury the number of HO-1-immunoreactive cells was obviously higher in the injured area in both mice, particularly in Bach1(-/-) mice. The HO-1 was primarily induced in microglia/macrophage in both mice. CONCLUSIONS These results suggest that HO-1 modulates the secondary injury process, and high HO-1 expression may preserve spinal cord function in the early stages after SCI in Bach1(-/-) mice. Treatment that induces HO-1 expression at these early stages may preserve the functional outcome after SCI.

Effects of pravastatin (CS-514) on biliary lipid metabolism in patients with hyperlipidemia

Pravastatin was administered to 20 patients with hyperlipidemia type IIa and IIb, for a period of 8 to 16 weeks at a daily dose of 10 to 20 mg, to investigate the effects on serum and biliary lipids. At the end of the treatment with pravastatin, the serum cholesterol level was significantly reduced, by 20%, compared with the control level. On the other hand, no significant differences were observed in serum high-density lipoprotein (HDL) cholesterol and triglyceride levels. Additionally, the administration of pravastatin did not change mode % compositions of biliary lipids, such as cholesterol, phospholipids, and total bile acids, as well as individual biliary bile acids. Consequently, there was not any significant change of the cholesterol saturation index. Based on the above results, our findings suggest that, for the treatment of hyperlipidemia, pravastatin is a highly effective cholesterol-lowering drug that does not affect biliary lipid metabolism.

Effects of fluvastatin on humanbiliary lipids

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have rapidly become widespread in the treatment of hypercholesterolemia and are known to be variable in efficacy. To investigate the effect on biliary lipids, a 3-month study using fluvastatin was devised. A total of 19 patients were enrolled in this study: all had hypercholesterolemia (7 men, 12 women; 13 with type IIa, 6 with type IIb). After an observation period of 4-6 weeks with placebo, fluvastatin at a daily dose of 30 mg was administered for 3 months. Fasting blood samples were taken early in the morning, before, and once a month during 3 months of fluvastatin treatment, for measurement of serum lipids. Cerulein-stimulated bile in the gallbladder was sampled using a duodenal tube, and the changes in biliary lipids were assessed. There was a marked decrease in serum total cholesterol after 12 weeks of treatment (21%; p < 0.001). However, there was no significant difference in the bile cholesterol saturation index (CSI): values before and after 3 months of drug administration were 0.93 and 0.99, respectively (Admirand-Small method). There were no significant changes in either the fatty acid composition of biliary lecithin or in the bile acid composition of bile. In conclusion, on the basis of these results, short-term (3 months) administration of fluvastatin does not appear to affect CSI.

Hypolipidemic effect of beraprost sodium in patients with arteriosclerosis obliterans accompanied by hyperlipidemia

Abstract The effect of beraprost sodium, a stable prostaglandin I 2 analog, on plasma lipids and apolipoproteins was examined in 18 patients with arteriosclerosis obliterans (Fontaine I) accompanied by hyperlipidemia. Twelve weeks of therapy with beraprost sodium at 120 μg daily significantly decreased plasma total cholesterol and low-density lipoprotein (LDL) cholesterol levels without a deleterious effect on plasma triglyceride, high-density lipoprotein (HDL) cholesterol, or apolipoprotein levels. A positive correlation was observed between the change in plasma total cholesterol and that in plasma LDL cholesterol due to the administration of beraprost sodium. Although this is a preliminary study, the results suggest beraprost sodium exerts an antiatherogenic effect. By lowering plasma total cholesterol and LDL cholesterol levels, beraprost sodium may prove to be important in the control of arteriosclerosis obliterans with hyperlipidemia.