Rosuvastatin Increases α-1 Microglobulin Urinary Excretion in Patients With Primary Dyslipidemia

The renoprotective effect of statins has been recently disputed because of observations of proteinuria associated with rosuvastatin treatment, the newest drug of the class. Statin-induced proteinuria findings were mainly based on crudely quantitative dipstick assays. The authors quantitatively evaluated the effect of rosuvastatin at the recommended starting dose of 10 mg/d, on urine protein excretion in patients with primary dyslipidemia. Serum lipid and nonlipid parameters as well as urinary electrolyte, creatinine, and protein (total, albumin, immunoglobulin G, and alpha-1 microglobulin) levels were measured in 40 patients treated with rosuvastatin and 30 controls at baseline and after 12 weeks. The protein-to-creatinine ratios were used to assess urinary protein excretion. Rosuvastatin improved the lipid profile, produced no deterioration of kidney function, but induced a small but significant increase in the excretion of alpha-1 microglobulin (by 16%, P < .05) indicating that statin-related proteinuria involves low-molecular-weight proteins and is of proximal tubular origin.

Increased serum ferritin concentrations and liver enzyme activities in patients with metabolic syndrome

Emerging scientific evidence suggests that increases in body iron represent a risk factor for the development of metabolic syndrome and diabetes. The aim of our study was to determine the body iron stores in patients with metabolic syndrome, and to evaluate the potential relationship of iron overload with specific features of the metabolic syndrome, such as fatty liver. A total of 490 individuals were enrolled. The diagnosis of metabolic syndrome was based on National Cholesterol Education Program-Adult Treatment Panel III (ATPIII) criteria. The metabolic syndrome group was consisted of 185 patients having three or more criteria, whereas individuals with less than three criteria constituted the control group. Metabolic syndrome patients displayed higher ferritin concentration as compared to control individuals. Ferritin levels were positively correlated with insulin concentration, as well as with Homeostasis Model Assessment (HOMA) index values. Multiple regression analysis revealed that ferritin was the most important independent determinant of insulin resistance indices. Patients with metabolic syndrome also exhibited increased concentrations of alanine aminotransferase and gamma-glutamyltranspeptidase compared to controls. Multiple regression analysis revealed that ferritin concentration was the most important determinant of gamma-glutamyltranspeptidase levels. Patients with the metabolic syndrome exhibit an increase in body iron stores as well as elevated concentrations of liver enzymes compared to the individuals who do not fulfill the criteria for the diagnosis of this syndrome. Our data support a direct role of increased body iron in the pathogenesis of insulin resistance, whereas iron overload may also contribute to the development of specific features of the metabolic syndrome, such as fatty liver.

The relationship of vitamin D with non-traditional risk factors for cardiovascular disease in subjects with metabolic syndrome

INTRODUCTION

Several studies implicate an inverse relationship between 25-hydroxy vitamin D (25(OH)Vit D) serum levels and metabolic syndrome (MetS). We sought to investigate a possible relationship between 25(OH)Vit D and emerging risk factors associated with MetS, such as small dense low-density lipoprotein cholesterol (sdLDL-C) concentration, lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) activity and high-sensitivity C-reactive protein (hsCRP) levels.

MATERIAL AND METHODS

We studied 110 consecutive otherwise healthy individuals. Of these, 52 were diagnosed with MetS and 58 who did not meet the MetS criteria served as controls. Low-density lipoprotein (LDL) subclass analysis was performed by polyacrylamide gel electrophoresis. Lp-PLA(2) activity was determined in total plasma by the trichloroacetic acid precipitation procedure. Serum 25(OH)Vit D was determined quantitatively by an enzyme immunoassay method.

RESULTS

Metabolic syndrome subjects had significantly lower 25(OH)Vit D levels (11.8 [0.6-48.3] ng/ml; 29.5 [1.5-120.75] nmol/l) compared with controls (17.2 [4.8-62.4] ng/ml; 43 [12-156] nmol/l, p = 0.027). Univariate regression analysis showed that 25(OH)Vit D concentration was inversely related to triglycerides (r= - 0.416, p = 0.003) and sdLDL-C (r= - 0.305, p = 0.004). There was no association of 25(OH)Vit D with waist circumference, blood pressure, high-density lipoprotein cholesterol (HDL-C), fasting glucose, Lp-PLA(2) and hsCRP. In multivariate regression analysis the relationship between 25(OH)Vit D and sdLDL-C became insignificant when triglycerides were included in the model.

CONCLUSIONS

Subjects with MetS exhibit lower 25(OH)Vit D serum levels compared with non-MetS individuals. Low 25(OH)Vit D is associated with higher sdLDL-C levels possibly through elevated triglycerides. No association between 25(OH)Vit D and Lp-PLA(2) or hsCRP was found.

Plasma triglyceride levels and body mass index values are the most important determinants of prebeta-1 HDL concentrations in patients with various types of primary dyslipidemia

OBJECTIVE

Experimental studies have shown that the prebeta-1 subclass of high-density lipoprotein particles (prebeta-1 HDL) may play an important role in the reverse cholesterol transport pathway as the initial acceptors of cellular cholesterol. The aim of the present study was the direct comparison of prebeta-1 HDL values in individuals with various types of primary dyslipidemias.

METHODS

Four hundred and eighty-six unrelated individuals were included in the study. According to their lipid values study participants were subdivided into four groups: control group (n=206), type IIA dyslipidemia group (n=148), type IIB dyslipidemia group (n=49) and type IV dyslipidemia group (n=83).

RESULTS

All dyslipidemic patients displayed higher concentrations of prebeta-1 HDL compared to control individuals. However, patients with dyslipidemias characterized by an abnormal catabolism of triglyceride-rich lipoproteins (such as dyslipidemias of type IIB and IV) tend to have higher prebeta-1 HDL values compared to patients with hypercholesterolemia, and this increase is proportional to the degree of hypertriglyceridemia. In addition, patients with metabolic syndrome exhibited significantly higher levels of prebeta-1 HDL compared to individuals that do not fulfill the criteria for the diagnosis of this syndrome. Multiple regression analysis revealed that serum triglyceride concentrations and body mass index (BMI) values were the most important determinants of prebeta-1 HDL levels in our population.

CONCLUSION

All dyslipidemic patients exhibit increased prebeta-1 HDL concentrations as compared to normolipidemic individuals. Whether this increase represents a defensive mechanism against atherosclerosis or it is indicative of impaired maturation of HDL particles and thus of a defective reverse cholesterol transport mechanism remains to be established.

Effect of ezetimibe monotherapy on the concentration of lipoprotein subfractions in patients with primary dyslipidaemia

BACKGROUND

Recent studies suggest that the distribution of lipoprotein subfractions is an independent predictor of vascular events. Therefore, we evaluated the effect of ezetimibe (a selective cholesterol transport inhibitor) on the concentrations of lipoprotein subfractions in patients with primary dyslipidaemia.

MATERIALS AND METHODS

Patients (n = 50) with primary dyslipidaemias were recruited. The concentrations of the individual lipoprotein subfractions were measured using the Lipoprint system at baseline and after 16 weeks of treatment.

RESULTS

Ezetimibe reduced total, low-density lipoprotein cholesterol (LDL-C) and non-high-density lipoprotein cholesterol (HDL-C) values as well as apolipoprotein B concentrations. Subfractionation of apolipoprotein B-containing lipoproteins showed that the reduction in LDL-C values was due to a fall in the concentrations of all LDL subfractions. However, a more pronounced trend towards a decrease in the concentrations of dense LDL subfractions was observed. Patients with triglyceride values >1.7 mmol/L had significantly greater reductions in the concentrations of small, dense LDL particles compared with those with normal triglyceride levels (49 vs. 19%, respectively; p < 0.05). Ezetimibe decreased the concentrations of HDL-C mainly due to a fall in the concentration of dense HDL subfractions.

CONCLUSION

Ezetimibe can favourably affect the distribution of LDL subfractions, especially in patients with elevated triglyceride values. Further studies are needed to clarify the significance of the ezetimibe-induced reduction in the concentrations of dense HDL particles.

Plasma lipoproteins and triacylglycerol are predictors of small, dense LDL particles

Recently published data suggest that the assessment of LDL subfraction profiles may contribute to the determination of the cardiovascular risk. In this study, we tested the ability of various metabolic parameters to estimate the presence or the preponderance of small, dense LDL particles (sdLDL). One hundred and fifty individuals attending the Outpatient Clinics of the University Hospital of Ioannina for suspected metabolic abnormalities were included in the study. Individuals were excluded if they were found to be diabetic or if they had a history of cardiovascular disease. Patients with thyroid dysfunction, liver or kidney diseases as well as those receiving drugs that may interfere with lipids or glucose metabolism were also excluded from the study. The ability of the various parameters to identify individuals with pattern B LDL phenotype or, alternatively, with measurable quantities of sdLDL particles was tested with the calculation of the areas under the ROC curves. The ratio of triglycerides to HDL-C was the best predictor of the presence of the pattern B LDL phenotype. Nevertheless, when the variable of interest was the presence of measurable quantities of sdLDL subfractions, the ratio of apoB to apoAI had the best predictive ability. In conclusion the ratios of apoB to apoAI and of triglycerides to HDL-C can reliably predict the presence of measurable quantities of sdLDL particles and of the pattern B LDL phenotype, respectively. However, since the quantitative determination of sdLDL concentrations may contribute to the determination of the cardiovascular risk, whereas the role of the LDL particle size remains controversial, apoB to apoAI ratio could provide more valuable information compared to markers that simply predict the presence of the pattern B LDL phenotype.

Concentration and relative distribution of low-density lipoprotein subfractions in patients with metabolic syndrome defined according to the National Cholesterol Education Program criteria

It has been proposed that the most common lipid abnormalities associated with the metabolic syndrome are elevated triglyceride and low high-density lipoprotein concentrations as well as the existence of small, dense low-density lipoprotein (LDL) particles. However, so far there are only limited clinical data concerning the distribution of LDL particles in patients with this syndrome. The aim of our study was to directly determine the concentration and relative distribution of LDL subfractions in patients with metabolic syndrome. One hundred seventy-five individuals were included. Patients with metabolic syndrome (n = 105) exhibited higher concentrations of dense LDL particles and lower mean LDL particle size than the control population (n = 70). Both of these parameters were significantly correlated with the number of components of metabolic syndrome. Multivariate analysis revealed that serum triglyceride concentration was the most important determinant of the presence of small, dense LDL particles. In conclusion, patients with metabolic syndrome exhibit higher concentrations of small, dense LDL subfractions than individuals who do not fulfill the criteria for the diagnosis of this syndrome. This increase is directly related to the number of components of metabolic syndrome and is mainly determined by the serum concentrations of triglycerides.

LDL cholesterol estimation in patients with the metabolic syndrome

BACKGROUND

The Friedewald formula (LDL-F) for the estimation of low-density lipoprotein (LDL) cholesterol concentrations is the most often used formula in clinical trials and clinical practice. However, much concern has been raised as to whether this formula is applicable in all patient populations such as the presence of chylomicronaemia and/or hypertriglyceridaemia. The aim of the present study was to evaluate various LDL cholesterol calculation formulas as well as LDL cholesterol levels provided by the Lipoprint LDL System (LDL-L) in patients with the metabolic syndrome (MetSyn).

RESULTS

LDL-F showed significant differences from other formulas in the total cohort, as well as in MetSyn individuals. This was not the case in nonMetSyn subjects, where LDL-F did not differ with other formulas, with the exception of one formula (LDL by Planella, LDL-P). The bias between LDL-F and other LDL estimation formulas were significantly higher in MetSyn subjects compared to nonMetSyn individuals, except for LDL-L which produced similar bias with LDL-F in both study groups.

CONCLUSION

LDL-F seems to exhibit some limitations as far as the calculation of LDL-C levels in patients with the MetSyn is concerned. LDL-L might be more accurate in MetSyn subjects, but so far its use is limited for the estimation of small, dense LDL (sdLDL) cholesterol levels and mean LDL particle size for research purposes only.

Lipoprotein-associated phospholipase A2 activity is a marker of small, dense LDL particles in human plasma

BACKGROUND

Recent clinical studies showed that lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is a predictor for incident atherosclerotic disease. We have previously shown that among the LDL subfractions, Lp-PLA(2) activity is preferentially associated with the atherogenic small, dense (sdLDL) particles in vitro. We investigated whether Lp-PLA(2) could be a marker of sdLDL in human plasma.

METHODS

One hundred and seventy-six individuals participated in the study. LDL subclass analysis was performed by polyacrylamide gel electrophoresis. Lp-PLA(2) activity and mass were determined in total plasma and in apolipoprotein B-depleted plasma (HDL-Lp-PLA(2)). Non-HDL-Lp-PLA(2) activity and mass were calculated by subtracting the HDL-Lp-PLA(2) from total plasma Lp-PLA(2).

RESULTS

On the basis of the LDL subclass analysis, participants were categorized into phenotype A and non-A (total cholesterol mass of the sdLDL subfractions < or =0.155 and >0.155 mmol/L, respectively). Unlike total plasma Lp-PLA(2) mass, total plasma Lp-PLA(2) activity and non-HDL-Lp-PLA(2) activity and mass were significantly higher in persons with phenotype non-A compared with persons with phenotype A, whereas HDL-Lp-PLA(2) activity and mass were lower in persons with phenotype non-A compared with phenotype A. Total plasma activity and non-HDL-Lp-PLA(2) activity and mass, but not Lp-PLA(2) mass, were correlated with sdLDL-cholesterol mass, proportion, and mean LDL particle size. In multiple regression analysis, total plasma and non-HDL-Lp-PLA(2) activities were the second best predictors of the presence of sdLDL particles in human plasma after serum triglyceride concentrations. At serum triglyceride concentrations >1.356 mmol/L, total plasma and non-HDL-Lp-PLA(2) activity added significantly to the prediction of the presence of sdLDL in plasma.

CONCLUSIONS

Lp-PLA(2) activity, but not the enzyme mass, is a marker of sdLDL in human plasma.

Lipoprotein-associated PAF-acetylhydrolase activity in subjects with the metabolic syndrome

Plasma- and lipoprotein-associated activity of the platelet activating factor acetylhydrolase (PAF-acetylhydrolase, PAF-AH) plays an important role in inflammation and in atherosclerotic process, which are present in the metabolic syndrome (MS). Paraoxonase 1 (PON1) is an esterase associated with high-density lipoprotein (HDL) which contributes to the anti-atherogenic effects of this lipoprotein. We investigated the activities of both enzymes in 60 patients with MS and 110 age- and sex-matched subjects without it (non-MS group). Plasma PAF-AH activity was higher in the MS compared to the non-MS group, while HDL-PAF-AH and serum PON1 activities were lower in the MS compared to the non-MS group. Univariate regression analysis in the MS group showed that plasma PAF-AH activity was positively associated with systolic blood pressure, whereas HDL-PAF-AH activity was inversely associated with the homeostasis model assessments (HOMA) index. Both associations remained significant in the multivariate regression analysis, suggesting that insulin resistance and systolic hypertension are major determinants for the alterations in plasma and HDL-associated PAF-AH activity among those observed in MS patients.