Potentially protective effects of the Ser447-Ter mutation of the lipoprotein lipase gene against the development of coronary artery disease in Japanese subjects via a beneficial lipid profile.

Several DNA variants at the lipoprotein lipase (LPL) gene locus have been found to be associated with the plasma lipid levels and the prevalence of coronary artery disease (CAD). In particular, the Ser447-termination (Ter) mutation at the exon 9 of the LPL gene has the potential to elevate the plasma high-density lipoprotein (HDL) levels, but it remains unknown in the Japanese population. The present study investigated 93 CAD patients and 96 age- and sex-matched healthy controls. The Ser447-Ter mutation was determined by polymerase chain reaction restriction fragment length polymorphism method. The allelic frequency of the Ser447-Ter mutation was 0.103 in all subjects. The Ser447-Ter (GG and CG) group was associated with significantly higher levels of plasma HDL-cholesterol (p<0.001) and lower levels of plasma triglyceride than the CC group (p<0.02). The peak particle size of low-density lipoprotein (LDL) was significantly larger in the Ser447-Ter (GG and CG) group than in CC group (p<0.05). The frequency of the Ser447-Ter genotype in GG and CG was significantly lower in CAD than in the controls (11.9% vs 26%, odds ratio = 0.38; 95% confidence interval, 0.18-0.81; p<0.02). These results suggest that the Ser447-Ter mutation of the LPL gene is associated with high plasma HDL-cholesterol levels, low plasma triglyceride levels and a larger LDL particle size. This mutation may have a protective effect against the development of CAD via its favorable lipoprotein profile.

Association of seropositivity for antibody to Chlamydia-specific lipopolysaccharide and coronary artery disease in Japanese men.

Recent studies suggest an association between Chlamydia pneumoniae infection and coronary artery disease (CAD). To examine this relationship in Japanese men, serum IgA and IgG antibodies to Chlamydia-specific lipopolysaccharide were measured by enzyme-linked immunosorbent assay in 507 patients with CAD and 200 age-matched controls. CAD patients were divided into (1) 269 patients with myocardial infarction (MI) and (2) 238 patients with chronic coronary heart disease (CCHD). Compared with the control group, the CAD group did not differ in the prevalences of both antibodies (IgA: 23.7 vs 18.0%, p=0.10; IgG: 52.7 vs 51.0%, p=0.6). The index of IgG antibody was not significantly different between CAD and control groups (median 1.19 vs 1.18, p=0.3), whereas the index of IgA antibody was significantly higher in CAD than control group (median 0.60 vs 0.46, p<0.0001). Compared with the control group, the MI group had a significantly higher prevalence of IgA antibody (28.6 vs 18.0%, p=0.007); however, there was no difference in the prevalence of IgG antibody (58.0 vs 51.0%, p=0.13). The CCHD group did not differ in the prevalences of both antibodies (IgA: 18.1 vs 18.0%, p=0.9; IgG: 45.6 vs 51.0%, p=0.2). After the adjustment for coronary risk factors, odds ratios (ORs) of seropositive antibodies for CAD were 1.59 [95% confidence interval (CI): 0.88-2.87, p=0.12] for IgA seropositivity and 0.92 (95%CI: 0.58-1.47, p=0.7) for IgG seropositivity in all cases. In the MI and control groups, ORs of seropositive antibodies for MI were 2.67 (95%CI: 1.32-5.38, p=0.007) for IgA seropositivity, and 1.36 (95%CI: 0.79-2.36, p=0.2) for IgG seropositivity. This study discovered that IgA antibody to Chlamydia was significantly associated with CAD, especially with MI, in Japanese Men and the findings suggest that chronic infection of Chlamydia may be linked to the pathogenesis of MI.

Association of serum antioxidant capacity with coronary artery disease in middle-aged men.

The possible involvement of oxidative damage in the progression of atherosclerosis has been suggested. There is some evidence that antioxidant therapy may be beneficial for the prevention of coronary heart disease. In this study, we investigated the relationship between coronary artery disease (CAD) and serum antioxidative status by measuring the total antioxidant status (TAS). Other relevant antioxidants, such as retinol, alpha, gamma-tocopherol, ascorbic acid, alpha, beta-carotenoids, erythrocyte glutathione peroxidase (GSH-Px) and oxidative products, were also determined in 31 male CAD patients with angiographically defined CAD and 66 male controls, aged 40-70 years, in a case-control study. The TAS levels, ratio and the concentrations of retinol, albumin, total protein and HDL cholesterol were significantly lower in the CAD patients than in the controls (p<0.01), and alpha-tocopherol and alpha/gamma-tocopherol were significantly higher in the CAD patients than in the controls. The TAS level correlated positively with gamma-GTP, GPT, GOT and uric acid (p<0.01). A multiple regression analysis in the CAD patients revealed that the TAS levels correlated most negatively with the number of diseased vessels. The concentrations of carotenoids and GSH-Px, as well as the alpha/gamma-tocopherol ratio were also significantly associated. Although conditional logistic regression analysis suggested low levels of HDL-cholesterol to be a significant coronary risk factor (OR=5.1, 95% CI=1.09-24.3), the TAS level showed no significant independent contribution to CAD. This study demonstrated an association of antioxidant parameters with the atherosclerosis progression, however, it did not confirm antioxidants as an independent risk factor for CAD event.

Relationship between plasma homocysteine levels and saphenous vein graft disease after coronary artery bypass grafts.

The long-term efficacy of coronary artery bypass graft (CABG) surgery is limited by saphenous vein graft (SVG) disease. Elevated levels of plasma homocysteine are a known independent risk factor for cardiovascular disease. However, its influence on the patency of SVG is unknown. To determine whether plasma homocysteine levels are related to SVG disease after CABG we measured homocysteine levels in 80 patients who underwent CABG (age: 64+/-8, interval after bypass surgery: 6.4+/-3.1, range: 1-13 years). The patients were divided into a vein graft disease group (more than 50% angiographical stenosis in any vein graft, n=40) and a no-vein graft disease group (<50% stenosis in any vein graft, n=40). The presence of a mutation in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene was also determined by polymerase chain reaction. Homocysteine levels in the vein graft disease group were significantly higher than in the no-vein graft disease group (11.2 vs. 9.1 micromol/l, p=0.01). Multiple regression analysis showed that the interval after CABG was an independent factor for SVG disease (odds ratio: 1.014, 95% confidence intervals: 1.003-1.025, p=0.013) and elevated levels of homocysteine tended to be an independent factor for SVG disease (odds ratio: 1.098, 95% confidence intervals: 0.994-1.213, p=0.067). There was no significant difference in MTHFR genotypes between the two groups. These findings indicate that elevated levels of plasma homocysteine are related to SVG disease after CABG.

High prevalence of seropositivity for antibodies to Chlamydia-specific lipopolysaccharide in patients with acute coronary syndrome.

BACKGROUND: Results of recent studies have demonstrated that there is an association between infection with Chlamydia pneumoniae and coronary artery disease (CAD). Inflammatory response caused by chlamydial infection has been considered to contribute to the development of atherosclerosis in coronary arteries. OBJECTIVE: The aim of this study was to investigate the specific relations between chlamydial infection and coronary events in patients with CAD. METHODS: We measured serum levels of immunoglobulin A and G antibodies against Chlamydia spp.-specific lipopolysaccharide in 155 patients with CAD and 60 age-matched and sex-matched healthy controls by enzyme-linked immunosorbent assay. CAD patients were divided into groups of the patients with acute coronary syndrome [(ACS), n = 35], old myocardial infarction [(OMI), n = 60] and chronic coronary heart disease [(CCHD), n = 60]. RESULTS: Prevalence of both seropositive antibodies in the control group and CCHD group were not different. In contrast, in ACS group there were significantly higher prevalences of seropositive immunoglobulin A (46 versus 12%, P = 0.0001) and G (74 versus 45%, P = 0.005) antibodies and in OMI group there was a significantly higher prevalence of seropositive immunoglobulin A antibodies (28 versus 12%, P = 0.02). Furthermore, compared with CCHD group, in ACS group there were significantly higher prevalences of seropositive immunoglobulin A (P = 0.00006) and G (P = 0.002) antibodies and in OMI group there was a higher prevalence of seropositive immunoglobulin A (P = 0.01). Adjustment for confounding factors did not change these findings. CONCLUSIONS: Infection with Chlamydia is significantly associated with ACS and OMI, but not with CCHD. These findings suggest that chronic and reactive infection with Chlamydia can lead to disruption of vulnerable plaque in patients with ACS.

Common polymorphism in the promoter of the CD14 monocyte receptor gene is associated with acute myocardial infarction in Japanese men.

We investigated whether C(-260)-->T polymorphism in the promoter of the CD14 monocyte receptor gene predisposed to coronary atherosclerosis and acute myocardial infarction (AMI) in Japanese men. The frequencies of T allele and T/T homozygotes in patients with AMI were significantly higher than in controls and in patients with angina without prior AMI, suggesting that the CD14 promoter polymorphism is associated with AMI rather than with coronary atherosclerosis, and this polymorphism may be one of the genetic risk factors for AMI in Japanese men.

Troglitazone improves endothelial dysfunction in patients with insulin resistance.

Insulin resistance is a possible major metabolic cause of atherosclerosis. Endothelial dysfunction is commonly found in patients with insulin resistance, and primary treatment of insulin resistance with troglitazone should improve such endothelial dysfunction. Thus, the effects of troglitazone on endothelial function were investigated. Thirteen non-diabetic male subjects with hyperinsulinemic response to oral glucose load (n = 7) and normal (n = 6) subjects were investigated. Flow-mediated dilatation (FMD) of the brachial artery was examined by high resolution ultrasonography before and after the administration of troglitazone of 400 mg for 4 weeks. In insulin resistant subjects, fasting glucose (4.9+/-0.3 to 4.7+/-0.3 mmol/L, p<0.05), insulin (45+/-30 to 25+/-15 pmol/L, p<0.05) and response to oral glucose load (AUC glucose: 15.0+/-3.5 to 13.0+/-2.2 mmol x h/L, p<0.05; AUC insulin: 965+/-560 to 475+/-275 pmol x h/L, p<0.05) were significantly reduced. FMD was significantly improved in insulin resistant subjects. A significant negative correlation was observed between FMD and AUC insulin (r=-0.64, p<0.05). The present study demonstrates that FMD is impaired in insulin resistant subjects, and troglitazone improves the blunted vascular response and impaired insulin response. This finding suggests that primary treatment of insulin resistance could prevent the development of atherosclerosis by improving endothelial dysfunction.

[Association between chlamydial infection and coronary artery disease].

Recent epidemiological studies have demonstrated the association between Chlamydia pneumoniae infection and coronary atherosclerosis. However, the relationship is less clear in the Japanese population. Serum IgA and IgG antibodies to Chlamydia-specific lipopolysaccharide were measured by enzyme-linked immunosorbent assay in 152 consecutive patients(112 males, 40 females, mean age 57 years)who underwent coronary angiography. Patients(n = 123)with coronary artery disease(CAD)were defined as having more than 50% diameter stenosis in at least one major coronary artery. The control group(n = 29) had normal coronary angiograms. In the CAD group, there was a high tendency of prevalence of IgA(20% vs 7%, p = 0.08)and IgG(54% vs 34%, p = 0.052). Prevalence of either IgA or IgG was significantly higher (59% vs 38%, p = 0.045) compared with the control group. Although the index of IgA antibody was not significantly different between the CAD and control groups(median 0.52 vs 0.36, p = 0.19), the index of IgG antibody was significantly higher in the CAD group than in the control group(median 1.29 vs 0.82, p = 0.026). The odds ratios for CAD were 3.4[95% confidence interval(CI)0.6-18.7]for the prevalence of IgA, 2.3(95% CI 0.9-5.2)for the prevalence of IgG, and 2.3(95% CI 1.0-5.2)for the prevalence of either IgA or IgG. Patients with CAD tended to have high prevalence of antibodies to Chlamydia spp, and these findings suggest an association between chlamydial infection and coronary atherosclerosis in the Japanese population.

Effects of troglitazone on atherogenic lipoprotein phenotype in coronary patients with insulin resistance.

Insulin resistance is associated with atherogenic lipoprotein phenotype, including small dense LDL particle, hypertriglycemia and low HDL cholesterol levels. Troglitazone, a novel insulin sensitizing agent, may improve the associated lipid profile in patients with insulin resistance. We examined the effects of troglitazone (400 mg daily for 12 weeks) in 12 non-diabetic coronary patients (60+/-10 years), all of whom had hyperinsulinemic response to an oral glucose load. Troglitazone markedly reduced the insulin response. After the treatment, plasma triglycerides decreased by 32% (P<0.05), HDL cholesterol increased by 11%, (P<0.05) and LDL peak particle diameter increased from 24.7+/-0.3 to 25.5+/-0.5 nm (P<0.01). These lipidic improvements were associated with a significant rise in postheparin lipoprotein lipase levels (175+/-52 to 217+/-69 ng/ml, P<0.01). In patients with insulin resistance syndrome, troglitazone improved the atherogenic lipoprotein phenotype as well as hyperinsulinemia. Our data suggest that troglitazone therapy could reduce the atherosclerotic risk due to insulin resistance even in non-diabetic patients.

Possible role of high susceptibility of high-density lipoprotein to lipid peroxidative modification and oxidized high-density lipoprotein in genesis of coronary artery spasm.

Recent study demonstrated high susceptibility of plasma LDL to lipid peroxidative modification in patients with variant angina. Oxidized stress state, especially oxidized LDL, may induce coronary artery spasm by its impairing effect of endothelium-dependent arterial relaxation, but precise mechanisms remain unclear. Study subjects included 93 patients who underwent coronary angiographic examination: 12 patients with coronary artery spasm provoked by ergonovine without organic stenosis (group I), 11 patients who did not demonstrate coronary artery spasm or organic stenosis (group II) and 70 patients with organic coronary artery stenosis (group III). Levels of plasma HDL-cholesterol and apoA-I in group I were similar to those in III but were significantly lower than those in II, although the other plasma lipid parameters were not different among the three groups. The levels of TBARS in plasma and HDL were significantly higher in group I than in II or III (2.94+/-1.56 vs. 1.91+/-0.35 or 2.23+/-0.89 nmol MDA/ml and 1.23+/-1.00 vs. 0.54+/-0.37 or 0.70+/-0.63 nmol MDA/mg protein; P < 0.05), although the levels of TBARS in LDL were not significantly different. In the monitoring curve of diene production during copper-induced lipid peroxidation of HDL, its propagation slope was steeper and levels of maximum diene absorbance was higher in group I as compared with that in II or III, but not found in those of LDL. These results suggested that high susceptibility of HDL to lipid peroxidative modification in group I may contribute to the genesis of coronary artery spasm, and oxidized HDL rather than oxidized LDL is more likely to be related to coronary artery spasm.

[Recent advanced knowledges related with lipoprotein metabolism].

This article aims to highlight recent advanced knowledges in enzymes and transfer protein in lipoprotein metabolism, including lipoprotein lipase (LPL), hepatic triglyceride lipase (HTGL), lecithin: cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP). In addition to its traditional role in the hydrolysis of lipoproteins, recent studies have revealed other functions of LPL and HTGL which may serve as ligands of cell surface receptors and/or proteoglycans. Clinical studies also have demonstrated new aspects in genetic polymorphism of both enzymes related with coronary artery disease. Several animal models have provided exact functions of LCAT and CETP which play an important role of reverse cholesterol transport. Clinical approach of CETP deficiency may be useful to identify the mechanism of atherosclerosis.

[Elevated levels of plasma homocysteine related to saphenous vein graft disease after coronary artery bypass graft surgery].

Elevated levels of plasma homocysteine may be an independent risk factor for coronary atherosclerosis. This study investigated whether plasma homocysteine levels are related to atherosclerotic lesions of saphenous vein grafts after coronary artery bypass surgery. Homocysteine levels were measured in fasting plasma by high-performance liquid chromatography and total cholesterol, triglyceride, high density lipoprotein cholesterol and lipoprotein (a) were also evaluated in 40 patients (mean age 65 +/- 8 years, mean interval after bypass surgery: 6.1 +/- 3.1 years, range 1-13 years). The vein graft disease group was defined as patients with angiographical stenosis of > or = 50% in any vein graft (n = 23). The other patients were defined as the no-vein graft disease group (n = 17). Patients who had a history of chronic renal failure or anatomic lesions of saphenous vein grafts were excluded. The distributions of homocysteine were skewed. Median homocysteine levels were 11.9 nmol/ml in all subjects. Homocysteine levels in the vein graft disease group were significantly higher than in the no-vein graft disease group (median 15.1 vs 10.6 nmol/ml, p = 0.01). In the analysis of plasma lipids, high-density lipoprotein cholesterol levels were significantly lower in the vein graft disease group than in the no-vein graft disease group (mean 37 +/- 11 vs 48 +/- 13 mg/dl, p = 0.01). Multiple regression analysis showed that elevated levels of homocysteine were an independent risk factor for saphenous vein graft disease after coronary artery bypass surgery. These findings indicate that elevated levels of plasma homocysteine are related to atherosclerotic lesions of saphenous vein grafts after coronary artery bypass surgery as well as coronary atherosclerosis.

High level of lipoprotein(a) is a strong predictor for progression of coronary artery disease.

Elevated levels of serum lipoprotein(a) [Lp(a)] are reported to be associated with risk of atherosclerosis and thrombosis. Little is known about the influence of Lp(a) on the progression of coronary artery disease. We evaluated the association of serum Lp(a) and the long-term changes of angiographic severity in patients who underwent repeated coronary angiography at intervals of more than 2 years. We evaluated 70 patients, and divided them into 3 groups by angiographic findings. Median Lp(a) concentration was significantly higher in the progression group (N=36) than in the no-change group (N=23) or the regression group (N=11) (32.4 vs 22, 19.3 mg/dl, p<0.05). Furthermore, the progression group had more patients whose Lp(a) levels were greater than 30 mg/dl (p=0.006), while in the regression group all patients were under 30 mg/dl. Stepwise logistic regression analysis for progression of lesions showed that Lp(a) > or =30 mg/dl remained significant, giving an estimated odds ratio (OR) of 2.46 (p= 0.005). In the subgroup analysis, OR in patients with mild lesions was reduced to 2.05 (p<0.05) while in patients with severe lesions OR was increased to 3.39 (p=0.003). The serum Lp(a) level has a close correlation with angiographic progression, and may be an important predictor for progression.

Lipoprotein(a) phenotypes in Japanese children: a cohort study.

BACKGROUND: Elevated serum lipoprotein(a) [Lp(a)] concentrations have been demonstrated to be associated with cardiovascular diseases due to premature atherosclerosis. However, the association of Lp(a) phenotypes with the development of these diseases remains largely unexplored. METHODS: We analyzed the population-based frequencies of serum Lp(a) phenotypes in 269 Japanese children aged 8-13 years in one community. According to the different apolipoprotein(a) [apo(a)] electrophoretic mobilities, Lp(a) was classified into seven single-band and respective double-band phenotypes. Each individual expressed a single (homozygotic) or a double band (heterozygotic). RESULTS: The serum Lp(a) concentration frequency distribution was skewed toward lower levels with a mean +/- SD of 15.5 +/- 18.0 mg/dl and a median of 11.0 mg/dl. The Lp(a) phenotype frequencies revealed that the frequency of double-band phenotype expression (55%) was higher than that of single bands (44%) and that the frequency of phenotypes representative of low molecular weight apo(a) was very low (2%). The mean serum Lp(a) concentration of the double-band-expressing subjects was higher than that of subjects with the single-band phenotype (20.1 +/- 19.9 vs. 10.5 +/- 15.9 mg/dl, p < 0.01). CONCLUSIONS: These findings of Lp(a) phenotypes in children seemed to differ from those in Japanese adults in another study; contrary to expectation, the predominant Lp(a) phenotypes found in children were those frequently associated with cardiovascular diseases in adults. Thus, it is speculated that children whose Lp(a) phenotypes remain unchanged during the transition to adulthood may show an increased susceptibility to cardiovascular disease, although the nutritional effects on the Lp(a) phenotypes cannot be neglected.

Relationship between HLA-C locus and restenosis after coronary artery balloon angioplasty.

OBJECTIVES: To determine the relationship between human leukocyte antigen (HLA) loci and restenosis after percutaneous transluminal coronary angioplasty (PTCA). DESIGN AND SETTING: Cross-sectional study in patients treated by PTCA at Juntendo University Hospital, Tokyo, Japan. PATIENTS: A total of 65 patients (58 males and 7 females) with coronary artery stenosis who were consecutively selected between October 1994 and June 1995. MAIN OUTCOME MEASURES: Significant relationships between the restenosis and the HLA-Cw1. RESULTS: Among HLA-C locus, Cw1 was negatively related to restenosis (multivariate adjusted odds ratio, 0.19; 95% confidence interval, 0.06-0.63; P=.007). CONCLUSIONS: In HLA typing, Cw1 may be a useful marker for the prediction of restenosis after PTCA.

Characterization of low-density lipoprotein subclasses in children.

Low-density lipoprotein (LDL) particles are heterogeneous in density, size, and chemical composition, and this heterogeneity is thought to be genetically influenced. In the present study, plasma LDL subclasses in 248 children aged 7 to 13 years were analyzed by gradient gel electrophoresis. The prevalence of small dense LDL (SDLDL), a potent atherogenic LDL, was 9.3%, which is lower than that reported in adults. Furthermore, children with this LDL subclass showed increased body fatness and dyslipidemia, including elevated plasma triglyceride and apolipoprotein (apo) B concentrations and decreased plasma high-density lipoprotein (HDL) cholesterol and apo A-I concentrations, compared with children without this phenotype. These findings suggest that in addition to genetic factors, environmental factors that affect these cardiovascular risk factors may also influence expression of the SDLDL subclass.

[Ultrasonographic assessment of carotid atherosclerosis emphasizing the variety of intimal-medial thickness and the relationship with coronary risk factors].

Intimal-medial thickness (IMT) of the extracranial carotid arteries measured by B-mode ultrasonography has been used as a marker of systemic and coronary atherosclerosis. Previous studies have indicated that maximum and mean carotid IMT are significantly correlated with the extent and severity of coronary artery disease (CAD), but the clinical usefulness of these markers is limited because they are neither specific nor sensitive enough to identify patients with or without significant CAD. The correlation of a new IMT marker, variance of IMT, with coronary risk factors and coronary atherosclerosis was investigated in 200 patients who underwent carotid ultrasonography and coronary angiography. IMT was measured in 16 sites of the extracranial carotid arteries for the calculation of mean, maximum and variance of IMT. Univariate analysis showed that these three indexes were significantly correlated with age, serum lipoprotein (a) and hypertension. However, age was correlated weakly with variance of IMT. There were significant gender differences in the mean and maximum IMT but not in the variance. There were also significant correlations of mean IMT with smoking, and maximum and variance of IMT with high-density lipoprotein. Multiple logistic regression analysis in 100 age and sex matched patients indicated that the only significant predictor for CAD in this subgroup was variance of IMT (odds ratio = 1.6). These results indicated that each risk factor causes different morphologic manifestations in the carotid atherosclerotic lesion. Variance of IMT, which represents the irregularity of carotid IMT, was correlated well with CAD and appears to be useful for assessing systemic and coronary atherosclerosis.