Yoshio Kuga

Atherosclerotic Disease in Marked Hyperalphalipoproteinemia: Combined Reduction of Cholesteryl Ester Transfer Protein and Hepatic Triglyceride Lipase

Hyperalphalipoproteinemia (HALP) has been regarded as a beneficial state accompanied by a longevity syndrome. However, we reported the cases of markedly hyperalphalipoproteinemic subjects with juvenile corneal opacification. The patients had reduced postheparin hepatic triglyceride lipase (HTGL) activities, and one of them has recently been identified to be homozygous for a missense mutation in exon 15 (D442: G) in the cholesteryl ester transfer protein (CETP) gene. In the current study, to elucidate the clinical significance of and atherogenicity in marked HALP, we determined the incidence of atherosclerotic cardiovascular disease (ACD) in patients with marked HALP and characterized the lipoprotein abnormalities in those who had ACD, focusing especially on CETP and HTGL. The subjects were 201 patients (111 males and 90 females) with marked HALP ( > or = 2.58 mmol/L [100 mg/dL]), 67% of whom were demonstrated to have the CETP gene mutations in the intron 14 splice donor site or in exon 15. Their mean age was 54 +/- 15 years. Plasma levels of total cholesterol, HDL cholesterol, and triglyceride in all subjects were 6.28 +/- 1.78, 3.15 +/- 0.90, and 1.08 +/- 0.53 mmol/L, respectively. Ten of the male patients (9.0%) and two of the female patients (2.2%) had apparent ACD such as myocardial infarction, angina pectoris, and peripheral vascular diseases. Ten patients with HALP who had ACD were identified to be heterozygotes for CETP deficiency. To further clarify the characteristics of marked HALP in patients with ACD, we compared the plasma lipids, lipoproteins, CETP, and HTGL activities between heterozygotes for CETP deficiency who were with and without ACD.

Opposite effects on cholesterol metabolism and their mechanisms induced by dietary oleic acid and palmitic acid in hamsters

The effects of dietary oleic acid on cholesterol metabolism were investigated and compared with those of palmitic acid in hamsters. Addition of 5% oleic acid to a 0.1% cholesterol-supplemented diet decreased plasma total cholesterol, very low density lipoprotein (VLDL) cholesterol, and low density lipoprotein (LDL) cholesterol, increased hepatic LDL receptor activity, and decreased plasma cholesteryl ester transfer protein (CETP) activity in comparison with 0.1% cholesterol alone. In contrast, addition of 5% palmitic acid to a 0.1% cholesterol-supplemented diet increased total cholesterol and LDL-cholesterol, increased plasma CETP activity, and suppressed hepatic LDL receptor activity to a greater extent than 0.1% cholesterol alone. Neither oleic acid nor palmitic acid altered hepatic microsomal 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity, but oleic acid increased hepatic microsomal cholesterol 7 alpha-hydroxylase activity. These results suggest that dietary oleic acid inhibits the increases in total, VLDL-, and LDL-cholesterol induced by dietary cholesterol by preventing both LDL receptor suppression and increased CETP activity, whereas dietary palmitic acid augments the cholesterol-induced increases in total and LDL-cholesterol by both further suppression of LDL receptor activity and further stimulation of CETP activity.

Probucol Inhibits Neointimal Formation in Carotid Arteries of Normocholesterolemic Rabbits and the Proliferation of Cultured Rabbit Vascular Smooth Muscle Cells

The proliferation of vascular smooth muscle cells (VSMCs) plays an important role in the formation of atherosclerotic lesions and restenosis after angioplasty. It has been suggested that probucol inhibits VSMCs proliferation, but this effect has not been directly demonstrated. In this study we investigated the effect of probucol on neointimal formation after balloon injury in normocholesterolemic rabbits and examined whether probucol could inhibit the proliferation of rabbit cultured VSMC stimulated by fetal bovine serum (FBS). Probucol inhibited the formation of neointima by about 63% 2 weeks after balloon injury. Probucol inhibited the increase in the number of cultured VSMCs and bromodeoxyuridine (BrdU) incorporation stimulated by 10% FBS in a dose-dependent manner. Also, 10% FBS stimulated the activities of mitogen-activated protein kinase (MAP kinase) and protein kinase C (PKC) in cultured VSMCs. Probucol inhibited these activities in a dose-dependent fashion. These results suggest that probucol may inhibit neointimal formation after balloon injury in normocholesterolemic rabbits by preventing the proliferation of VSMCs via inactivation of MAP kinase and PKC.

Effect of fluvastatin sodium (XU62-320), a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on the induction of low-density lipoprotein receptor in HepG2 cells

The effect of fluvastatin sodium (XU62-320), a new type of inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A, on the induction of LDL receptor in the human liver-derived cell line HepG2 was investigated. Fluvastatin sodium produced marked inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and induction of LDL receptor on HepG2 cells at a concentration of 0.1-1.0 microM. These results suggest that fluvastatin sodium has potential for use as a strong plasma cholesterol-lowering drug.

Effect of dietary hydrogenated corn oil (trans-octadecenoate rich oil) on plasma and hepatic cholesterol metabolism in the hamster.

The effect of dietary hydrogenated corn oil (trans-octadecenoate-rich oil) on plasma cholesterol and triglyceride concentrations was compared with dietary palmitic acid in hamsters given a cholesterol-rich diet. The addition of dietary palmitic acid and hydrogenated corn oil accelerated the increase in plasma VLDL- and LDL-cholesterol levels and plasma triglyceride level induced by dietary cholesterol loading. Dietary cholesterol, palmitic acid and hydrogenated corn oil showed no effect on plasma HDL-cholesterol concentration. A decrease in hepatic LDL receptor activity was seen in animals fed a diet supplemented with cholesterol in combination with palmitic acid or hydrogenated corn oil in comparison with animals fed a diet supplemented with cholesterol alone. Hydrogenated corn oil (trans-octadecenoate-rich oil) appears to potentiate the effect of dietary cholesterol in elevating the plasma VLDL- and LDL-cholesterol levels through the suppression of hepatic LDL receptor activity. trans-Octadecenoate in dietary hydrogenated corn oil may be as atherogenic as dietary palmitic acid due to a suppression of hepatic LDL receptors in the presence of dietary cholesterol loading.

Reduction of Plasma Cholesterol Levels and Induction of Hepatic LDL Receptor by Cerivastatin Sodium (CAS 143201-11-0, BAY w 6228), a New Inhibitor of 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase, in Dogs

The effects of cerivastatin sodium (BAY w 6228), a new type of inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, on plasma cholesterol concentrations and the induction of hepatic LDL receptors were investigated with beagle dogs and Hep G2 cells. Oral administration of cerivastatin (0.01, 0.03, and 0.1 mg/kg per day) for 3 weeks reduced plasma total and very low-density lipoprotein plus low-density lipoprotein (VLDL + LDL) cholesterol concentrations and increased hepatic LDL receptor binding activity in dogs. Scatchard plot analysis revealed a 1.9-fold increase in the maximum binding capacity of hepatic LDL receptors in cerivastatin-treated animals. Similar results were obtained by administration of pravastatin (1.0 and 5.0 mg/kg/day) for 3 weeks. Binding activity of the LDL receptor, as well as receptor mRNA and protein concentrations, were increased in a dose-dependent manner (0.01–1.0 μM) by exposure of Hep G2 cells to cerivastatin. The results suggest that cerivastatin reduces plasma cholesterol concentrations by increasing hepatic LDL receptor expression. The mechanism of lowering cholesterol concentration by cerivastatin was the same as with the other previously examined HMG-CoA reductase inhibitors, but the effects with cerivastatin were apparent at doses much lower than the effective doses of the other drugs. Cerivastatin, therefore, shows potential for clinical use as a potent and efficacious plasma cholesterol-lowering drug.

Angiotensin-converting enzyme insertion/deletion genotype is associated with the activities of plasma coagulation factor VII and X independent of triglyceride metabolism

Background The D allele of angiotensin‐converting enzyme (ACE) insertion/deletion (I/D) polymorphism and coagulation activity play important roles in cardiovascular events, however, the precise association between these two risk factors remains unclear. Methods We identified the ACE I/D genotype and measured the plasma coagulation factor VII and X (FVII and FX) activities and serum lipids in 172 patients (110 men and 62 women, mean age 56.7 ± 13.3 years) undergoing coronary angiography. Results The frequency of the D allele was significantly higher in those with a history of myocardial infarction (MI) than in those with normal coronary arteries, but there was no significant association between FVII and FX activities and the stage of coronary disease. Plasma coagulation factor VII and FX activities were significantly lower in the DD genotype (n=42) than in the II genotype (n=67, P<0.001 and P<0.001, respectively) or the ID genotype (n=63, P<0.01 and P<0.05, respectively). The association of the ACE D allele with lower activities of FVII and FX was also seen in patients with coronary artery disease (CAD). There was a significant association between serum triglyceride levels with FVII and FX, but not with the ACE I/D genotype. Conclusion We concluded that the ACE I/D polymorphism may contribute more to the onset of MI than the activities of FVII and FX and that the ACE D allele might be associated with lower plasma activities of FVII and FX. The potential link between ACE I/D polymorphism and the plasma activities of FVII and FX is probably independent of triglyceride metabolism. Coron Artery Dis 14:285‐291 • 2003 Lippincott Williams & Wilkins.

Comparison of the Effect of Bezafibrate on Improvement of Atherogenic Lipoproteins in Japanese Familial Combined Hyperlipidemic Patients With or Without Impaired Glucose Tolerance

The effect of bezafibrate on plasma lipoproteins was investigated in Japanese familial combined hyperlipidemic patients with or without an impaired glucose tolerance accompanied by a low-density lipoprotein subclass, with the major gradient gel peak at a particle diameter of less than 25.5 nm. Bezafibrate treatment at a dose of 400 mg/d for 12 weeks produced an antiatherogenic effect on lipoprotein profiles, as reflected by a decrease in plasma triglyceride levels, an increase in plasma high-density lipoprotein-cholesterol levels, induction of the large-size subclass of low-density lipoprotein, and disappearance of intermediate-density lipoproteins. The plasma total and low-density lipoprotein-cholesterol-lowering effect of bezafibrate was significant in patients without impaired glucose tolerance but was not significant in patients with impaired glucose tolerance. Bezafibrate increased lipoprotein lipase activity and decreased the activity of cholesteryl ester transfer protein, both in patients with or without impaired glucose tolerance. There was no difference in the distribution of signal peptide insertion/deletion or Xbal polymorphisms of the apolipoprotein B gene in patients with or without impaired glucose tolerance. Mechanisms other than lipoprotein lipase, cholesteryl ester transfer protein activities, and an apolipoprotein B gene polymorphism may be responsible for the resistance to lowering of plasma total and low-density lipoprotein cholesterol levels with bezafibrate treatment in familial combined hyperlipidemic patients with impaired glucose tolerance.

Effect of pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitor, on hepatic cholesterol 7α-hydroxylase, acyl-coenzyme A: cholesterol acyltransferase, and bile lipid secretion in the hamster with intact enterohepatic circulation

The effects of administration of pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on hepatic cholesterol 7 alpha-hydroxylase and acyl-coenzyme A: cholesterol acyltransferase (ACAT) activities and bile lipid secretion were investigated in Syrian golden hamsters. Continuous administration of pravastatin induced no significant changes in hepatic cholesterol content, ACAT and cholesterol 7 alpha-hydroxylase activities, or bile lipid and acid composition. Abrupt withdrawal of pravastatin induced increases in hepatic cholesterol content and ACAT activity and no change in hepatic cholesterol 7 alpha-hydroxylase activity, and increased cholesterol saturation in bile. Hepatic cholesterol 7 alpha-hydroxylase activity paralleled hepatic mRNA levels of this enzyme. These results suggest that a change in hepatic cholesterol metabolism induced by continuous administration of pravastatin maintains a constant net balance of hepatic cholesterol content. In addition, the drug has no deleterious influence on metabolism of bile lipids and acids and related enzymes, except for a transient increase in cholesterol saturation in bile induced by an inappropriate increase in hepatic cholesterol content and a lack of response of cholesterol 7 alpha-hydroxylase activity to changes in hepatic cholesterol content upon abrupt withdrawal of pravastatin.

Amino Acid Transport System of the Guinea Pig Small Intestine is Injured by Hydroxyl Radicals

The mechanism for the damage to the alanine-preferring amino acid transport system (A system) of guinea pig intestinal brush border membrane vesicles induced by active oxygen species was studied in vitro. The transport activity of L-proline, which is a model amino acid for the A system, and the tryptophan fluorescence intensity of intestinal brush border membrane vesicles were decreased, and lipid peroxidation of these membrane vesicles was induced by ultraviolet irradiation, which generated active oxygen species. Thiourea (hydroxyl radical scavenger) protected L-proline transport activity and tryptophan fluorescence intensity of intestinal brush border membrane vesicles and also inhibited lipid peroxidation in these membrane vesicles in the presence of active oxygen radicals. alpha-Tocopherol (singlet oxygen radical scavenger) inhibited lipid peroxidation of intestinal brush border membrane vesicles but protected neither L-proline transport activity nor tryptophan fluorescence intensity in these membrane vesicles in the presence of active oxygen radicals. Catalase and superoxide dismutase showed no protective effect on L-proline transport activity, tryptophan fluorescence intensity, or lipid peroxide formation in intestinal brush border membrane vesicles in the presence of active oxygen radicals.(ABSTRACT TRUNCATED AT 250 WORDS)