Pharmacologic elevation of high-density lipoproteins: recent insights on mechanism of action and atherosclerosis protection

PURPOSE OF REVIEW

Despite the best efforts in reduction of low-density lipoprotein cholesterol, most cardiovascular events are not being prevented. Because high-density lipoprotein (HDL) promotes reverse cholesterol transport and other antiatherogenic effects, interventions aimed at raising HDL cholesterol or mimicking its beneficial effects may greatly improve treatment and prevention of cardiovascular disease. This article reviews the antiatherogenic effects of HDL, recent insights into the mechanisms of action of currently available, and emerging HDL-based therapies.

RECENT FINDINGS

New insights into the basic science of HDL function and metabolism (such as the discovery of beta-chain ATP synthase as a hepatic catabolic HDL receptor) are further characterizing the importance of HDL in atheroprotection and identifying novel targets of drug development. Nicotinic acid, fibrates, statins, and thiazolidinediones not only increase HDL cholesterol but also alter HDL subpopulation size and composition. Furthermore, these drugs promote direct antiatherogenic effects of HDL (antioxidation, anti-inflammation, antithrombotic effects, endothelial stabilization). Emerging HDL-raising therapies (such as cholesteryl ester transfer protein inhibitors and 1,2-dimyristoyl-sn-glycero-phosphocholine) and novel interventions that mimic HDL's beneficial effects (such as apolipoprotein AImilano and apolipoprotein AI mimetic peptides) are proving beneficial in animal and human studies.

SUMMARY

An understanding of the atheroprotective mechanisms of HDL is essential for the rational use of currently available drugs and directed development of new drugs. Increasing total HDL cholesterol may not be as important as increasing the functional properties of HDL. Cardiovascular disease treatment and prevention can be improved by combining current low-density lipoprotein-based strategies with effective HDL-based interventions.

Emerging therapeutic strategies for the management of dyslipidemia in patients with the metabolic syndrome

The benefits of lipid-lowering therapy in significantly reducing cardiovascular events has been established in many at-risk populations. However, patients with the metabolic syndrome (MS) pose a challenge for clinical management. A high degree of residual risk exists in patients with the MS or diabetes mellitus, and this is of growing importance because of the increasing prevalence of obesity and its associated comorbidities in the world. As the MS has emerged as a major risk factor for both cardiovascular disease and diabetes, targeting treatment to achieve aggressive goals becomes paramount. This article reviews emerging therapeutic strategies for the management of dyslipidemia in patients with the MS.

Effects of lipid-altering treatment in diabetes mellitus and the metabolic syndrome

The metabolic syndrome (MS) poses an increased risk for the development of diabetes mellitus and cardiovascular events. The syndrome typically includes dyslipidemia, characterized by elevated plasma triglycerides and low high-density lipoprotein cholesterol concentrations. Retrospective analyses of coronary artery disease outcomes trials in patient subpopulations with diabetes or the MS indicate that lipid-altering therapies provide benefits for patients with the MS at least as much as observed in patients without diabetes or the MS. Analyses of the effects of lipid-altering therapy on the lipid profile in patients with the MS also indicate that beneficial lipid changes are similar in patients with the MS compared with those in patients without the MS. The benefits of statin treatment in patients with the MS have become increasingly clear, and it is likely that further improvements in treatment may be achieved with newer statins or a combination of lipid-altering drugs. Prospective data from clinical trials examining the preventive effects of lipid-altering therapy in MS patients are needed to better define potential benefits and optimal treatment in this population.

Maternal birth weight in relation to plasma lipid concentrations in early pregnancy

OBJECTIVE

The purpose of this study was to determine the extent to which, if at all, maternal weight at birth is related to dyslipidemia during early pregnancy, which is a risk factor for preeclampsia.

STUDY DESIGN

This hospital-based prospective cohort study included 1000 women who initiated prenatal care before 16 weeks of gestation. Participants provided information about their birth weight and other sociodemographic and reproductive covariates. Plasma triglyceride, high-density lipoprotein cholesterol, and total cholesterol concentrations were measured at approximately 13 weeks of gestation. beta coefficients and standard errors were estimated by multiple linear regression; odds ratios and 95% confidence intervals were estimated by logistic regression.

RESULTS

Maternal birth weight was correlated negatively with triglycerides (r =-0.12; P =.001) and was correlated positively with high-density lipoprotein cholesterol (r =0.08; p =.02) but not statistically significantly related with total cholesterol (r =-0.004; P=.91). After adjusting for potential confounders, women who weighed <2500 g at birth had higher triglyceride and total cholesterol concentrations (beta=23.4 mg/dL [P<.001]; beta =2.6 mg/dL [P =.585], respectively) and lower high-density lipoprotein cholesterol concentrations (beta =-3.2 mg/dL; P=.105), when compared with women who weighed 3000 to 3499 g at birth. Women who were born small (<2500 g) and became overweight (body mass index, >or=25 kg/m(2)) in adulthood had less favorable lipid profiles than their counterparts who weighed >or=2500 g at birth and remained lean (body mass index, <25 kg/m(2)).

CONCLUSION

Our findings suggest that factors that are related to growth in utero may help to predict the subsequent risk of altered lipid metabolism during pregnancy, which may, in turn, be causally related to the occurrence of preeclampsia.

Introduction to risk assessment and serum risk markers for the prevention of coronary heart disease and other potential conditions that impact men's health, part I: what do I tell my patients?

This article covers the basic cholesterol profile and a method of assessing the potential risks for CHD for most men. It is hoped that this overview will assist clinicians and patients in raising the awareness of CHD as the leading cause of mortality in men, and help to place the overall risk for mortality into a proper perspective.

Raloxifene inhibits cholesterol aortic content but not atherosclerotic plaque size in oophorectomised cholesterol-fed rabbits

Raloxifene, a selective oestrogen receptor modulator, is effective in the treatment of osteoporosis without stimulating the breast and the endometrium. Although it is associated with a decrease of cardiovascular risk markers the effect of these changes on atherogenesis, is not clear. In this study, we aimed to investigate the effect of raloxifene on aorta atherogenesis. A total of 32 cholesterol-fed New Zealand white rabbits were studied for 4 months. Twenty-four rabbits underwent bilateral ovariectomy; of these eight received raloxifene (group OR), eight received oestradiol valerate (group OE) and eight received placebo after sterilisation (group OP). Finally, another eight were sham-operated (non-ovariectomised) and received placebo with a hypercholesterolaemic diet (group SP). After the diet, total levels of cholesterol increased in group SP from 111.25 +/- 34.8 mg/dl to 1112.25 +/- 364.2, in group OP from 122.62 +/- 27.7 mg/dl to 1367.37 +/- 348.4, in group OE from 65.25 +/- 17.01 to 1710.5 +/- 356.2 and in group OR from 108.88 +/- 15.54 mg/dl to 1407.86 +/- 397.7 (no significant differences). At 4 months, in both treated and untreated rabbits, the cholesterol-rich diet caused atherosclerotic lesions affecting 24.51 +/- 16.1% for group SP, 30.47 +/- 12.2% for group OP, 30.31 +/- 18.07% for group OR and 17.91 +/- 10.19 for group OE (P<0.05) of the aortic surface, respectively. Aortic cholesterol expressed as mg of cholesterol/mg aortic weight was found to decrease in raloxifene-treated rabbits: 3.82 +/- 2.14 mg col/aortic mg versus 8.55 +/- 4.63 (group OP) and 11.97 +/- 11.33 (group SP). P<0.001. Raloxifene reduced aortic cholesterol content but not the atherosclerotic plaque extension in cholesterol-fed ovariectomised rabbits.

In vivo oxidizability of LDL in type 2 diabetic patients in good and poor glycemic control

We aimed to determine if increased non-enzymatic glycosylation of the LDL was sufficient to increase the susceptibility to in vivo oxidation of the LDL particles. Twenty-two type 2 diabetic patients (11 males and 11 females) were included in this study. They were enrolled on the basis of good [glycated hemoglobin (HbA1c) < 7%] and poor glycemic control [(HbA1c) > 8%]. LDL were isolated by sequential ultracentrifugation and analyzed by capillary electrophoresis (CE) for diene conjugate content and for electronegativity. The glyc-LDL levels were increased in all diabetic type 2 patients, peaking in the diabetic subjects in poor diabetic control (17.3 +/- 8.07%). The LDL content of diene conjugates was similar between the two groups (6.65 +/- 0.77% for the patients with good glycemic control versus 6.88 +/- 0.74% for those with poor glycemic control; P = 0.49) as was the electrophoretic mobility ((-1.14544 +/- 0.089) x 10(-4) cm2/(V s) for the patients with good glycemic control and (-1.13666 +/- 0.073) x 10(-4) cm2/(V s) for those with poor glycemic control; P = 0.80). The susceptibility to in vivo oxidation of LDL from type 2 diabetic patients in poor glycemic control did not differ from that of well-controlled diabetic patients. LDL glycosylation was not able to increase the oxidizability of LDL in the diabetic patients with poor glycemic control.

The c.419-420insA in the MTP gene is associated with abetalipoproteinemia among French-Canadians

Abetalipoproteinemia (ABL) is a rare autosomal recessive disease characterised by the absence of apolipoprotein B (apoB) containing lipoproteins and, in consequence, very low triglyceride and cholesterol levels. Microsomal triglyceride transfer protein (MTP) has been associated with ABL. A search for sequence variants in the large subunit of MTP in a kindred of 10 individuals from Saguenay-Lac-St Jean area with a propositus exhibiting ABL as well as in four independent patients from the greater Quebec city area and exhibiting very low apoB and LDL-cholesterol levels identified 12 variations. Only one sequence variation, the c.419-420insA, was observed, in the homozygous form, in the abetalipoproteinemic patient. The -493G/-400A/-164T/282G/383T/419-420insA/453T/891C/969T/1151A/2884G haplotype carries the insertion and was found in all members of the family studied. In conclusion, the present study showed that the c.419-420insA alone, in the homozygous form, is a cause of classical recessive inherited ABL in the French-Canadian population.

Dyslipidemia in Asian Indians: determinants and significance

Data suggest that lipid fractions other than total cholesterol, i.e. serum triglycerides (TG) and high-density lipoprotein (HDL) cholesterol are important for the pathogenesis of atherosclerosis. A combination of hypertriglyceridemia, low levels of HDL-cholesterol and high levels of small dense low-density lipoprotein, termed as "atherogenic dyslipidemia', is particularly seen in Asian Indians. Although precise reason for such dyslipidemia is unknown, genetic predisposition and characteristic body composition (excess truncal subcutaneous fat and intraabdominal fat) may be important contributors. A common interface between such body composition and dyslipidemia in Asian Indians is high tendency to develop insulin resistance, more than the other ethnic groups. The general guidelines for the management of dyslipidemia in Asian Indians should be according to National Cholesterol Education Program, Adult Treatment Panel III. However, optimal management requires consideration of ethnic-specific dietary, lifestyle and management factors to formulate individual treatment guidelines.

Lipoprotein(a) as a marker of coronary artery disease and its association with dietary fat

OBJECTIVE

The main objectives of the study were to evaluate the effect of dietary fat on plasma lipoprotein(a) [Lp(a)] levels and to study the potential of Lp(a) as a more reliable marker for CAD compared to other lipids and lipoproteins.

METHODS

Twenty CAD patients and 20 healthy controls were recruited for the study. Their fasting plasma Lp(a) levels and complete lipid profile were assayed. The fat intake was calculated using 24 hours dietary recall method. The patients and controls were each divided into two subgroups: Group A consuming dietary fat > 30% and Group B consuming dietary fat < or = 30% of the total kilo-calories/day.

RESULTS

Results indicated that plasma Lp(a), total serum cholesterol (TC), tryglyceride (TG), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and LDL-C/HDL-C ratio of CAD patients were significantly higher than the controls. High fat intake was found to be associated with higher plasma Lp(a) levels (p<0.05) in patients only. No significant correlation was found between Lp(a) levels and other conventional lipoproteins.

CONCLUSION

The lack of correlation between Lp(a) and other lipoproteins indicates its potential as an independent risk factor for CAD. High fat intake led to higher plasma Lp(a) levels in patients; hence it would be worthwhile to evaluate the effect of quality and quantity of fat intake on plasma Lp(a) levels in a larger sample size.

Postprandial lipemia is modified by the presence of the polymorphism present in the exon 1 variant at the SR-BI gene locus

It has recently been reported that carriers of the less common allele at the scavenger receptor class B type I (SR-BI) exon 1 polymorphism are more susceptible to the presence of saturated fatty acid in the diet because of a greater increase in LDL cholesterol. Our aim was to determine if this polymorphism could also influence postprandial lipoprotein metabolism, because the SR-BI has been described as a possible mediator in the intestinal absorption of triacylglycerols. Forty-seven normolipidemic volunteers who were homozygous for the E3 allele at the APOE gene were selected [37 homozygous for the common genotype (1/1) at the SR-BI exon 1 polymorphism and 10 heterozygous (1/2)]. They were given a fat-rich meal containing 1 g fat and 7 mg cholesterol per kg body weight and vitamin A 60,000 IU/m2 body surface. Fat accounted for 60% of calories, and protein and carbohydrates accounted for 15% and 25% of energy respectively. Blood samples were taken at time 0, every 1 h until 6 h, and every 2.5 h until 11 h. Total cholesterol and triacylglycerols in plasma, and cholesterol, triacylglycerols and retinyl palmitate in triacylglycerol-rich lipoproteins (large and small triacylglycerol-rich lipoproteins) were determined. Postprandial responses for triacylglycerols and retinyl palmitate in small triacylglycerol-rich lipoproteins were higher in 1/1 individuals than in 1/2 individuals. No other significant differences were noted. Our data show that the presence of the genotype 1/2 is associated with a lower postprandial lipemic response.

Simplified method for the diameter sizing of serum low-density lipoprotein using polyacrylamide gradient gel electrophoresis

The appearance of small, dense, low-density lipoprotein in serum has been demonstrated to be associated with increased risk of coronary artery disease. The molecular diameter of low-density lipoprotein is usually measured on the basis of mobility differences on polyacrylamide gel electrophoresis. However, since mobility assessed by this method is seriously affected by the increased levels of serum free fatty acids associated with hypertriglyceridemia, we used polyacrylamide gradient gel electrophoresis to eliminate the interference by fatty acids and devised a simple, precise method of polyacrylamide gradient gel electrophoresis to measure the diameter of small, dense, low-density lipoproteins in serum. We used apoferritin and thyroglobulin, which have a molecular diameter of 12.2 nm and 17.0 nm, respectively, and standard low-density lipoprotein particles having a diameter of 25.7 and 27.0 nm as calibrators, estimated by measurement of negative staining of electron microscopy. We also included apoferritin as an internal standard for polyacrylamide gradient gel electrophoresis. The only stain used was Coomassie brilliant blue, and it was used for lipoprotein staining. When we used low-density lipoprotein of 25.73 nm in diameter as a quality control specimen, the coefficient of variation of the size measurements obtained by our method was less than 1.2%. The new method markedly improved the laboratory procedure for measuring the diameter of low-density lipoproteins.

Metabolic, inflammatory and haemostatic effects of a low-dose continuous combined HRT in women with type 2 diabetes: potentially safer with respect to vascular risk?

BACKGROUND

Conventional hormone replacement therapy (HRT) containing conjugated equine oestrogen (CEE) and medroxyprogesterone acetate (MPA) increases triglyceride, C-reactive protein (CRP) and coagulation Factor VII concentrations, potentially explaining their increased coronary heart disease (CHD) and stroke risk.

OBJECTIVE

To assess the metabolic effects of a continuous combined HRT containing 1 mg oestradiol and 0.5 mg norethisterone or matching placebo.

DESIGN

Double-blind, randomized placebo-controlled trial.

PATIENTS

Fifty women with type 2 diabetes.

MEASUREMENTS

Classical and novel risk factors for vascular disease.

RESULTS

Triglyceride concentration was not altered (P = 0.31, change in active arm relative to placebo) and low-density lipoprotein (LDL) cholesterol concentration declined 13% (P = 0.018). IL-6 concentration (mean difference -1.42 pg/ml, 95% CI: -2-55 to -0-29 IU/dl, P = 0.015), Factor VII (-32 IU/dl, -43 to -21 IU/l, P < 0.001) and tissue plasminogen activator antigen (by 13%, P = 0.005) concentrations fell, but CRP was not significantly altered (P = 0.62). Fasting glucose (P = 0.026) also declined significantly, but there are no significant effects on HBA1c, Factor IX or APC resistance.

CONCLUSIONS

HRT containing 1 mg oestradiol and 0.5 mg norethisterone may avoid the adverse metabolic effects potentially implicated in the elevated CHD and stroke risk induced by conventional higher dose HRT. This type of preparation may therefore be more suitable than conventional HRT for women at elevated CHD risk such as those with type 2 diabetes. Large randomized controlled trials of such low dose preparations, powered for cardiovascular end points, are now needed.

Treatment of hypercholesterolemia in patients with diabetes at a family practice office

BACKGROUND

Patients with diabetes have an increased risk of developing coronary heart disease (CHD) and therefore need optimal management of hypercholesterolemia. Previous studies have shown that management of these patients remains suboptimal.

OBJECTIVE

Our study aimed to determine the extent to which patients with diabetes in a family practice setting in Delaware are being managed according to national guidelines for the management of hypercholesterolemia.

METHODS

Using a retrospective medical chart review, we identified all active patients with diabetes in a family practice office. We determined the percentage of patients who had a low-density lipoprotein (LDL) documented in their chart and the percentage of patients who received LDL screening within the past year. We then stratified the sample into three different categories of LDL level (< 100 mg/dl, 100-129 mg/dl, and > or = 130 mg/dl) and determined the percentage of patients who were on lipid-lowering therapy within each stratum.

RESULTS

According to the medical record review, 80.30% of the active patients with diabetes had an LDL recorded in their chart. Of the patients with diabetes, 57.99% had an LDL measurement taken within the past year. Of this group, 41.03% had an LDL < 100 mg/dl, 31.41% had an LDL between 100 and 129 mg/dl, and 25.00% had an LDL > or = 130 mg/dl. Of the total number of patients with an LDL < 100 mg/dl, 53.93% were on lipid-lowering agents, while 38.18% of the patients with an LDL > or = 130 mg/dl were on lipid-lowering agents. Of the patients with an LDL measurement taken in the past year, 67.19% of those with an LDL < 100 mg/dl were on lipid-lowering medications, while 43.59% of patients with an LDL > or = 130 mg/dl were on lipid-lowering medications.

CONCLUSIONS

In a Delaware family practice office, the screening rate for hyperlipidemia in patients with diabetes is similar to that found in other studies, but still leaves room for improvement. Lipid control rates are somewhat better than the rates reported in previous studies, but they are still not optimal. While many of the patients requiring lipid-lowering therapy are on these medications, a substantial minority has an LDL of < 100 mg/dl without being on medications. Although these findings may reflect patient preference to defer medications, it suggests that there is room for improvement with medical therapy.

A novel and simple method for quantification of small, dense LDL

A preponderance of small, dense (sd) LDL is strongly associated with the development of coronary heart disease, but the method for the measurement of sd LDL is too laborious for clinical use. We report a simple method for the quantification of sd LDL that is applicable to an autoanalyzer. This method consists of two steps: first, to precipitate the lipoprotein of density (d) <1.044 g/ml using heparin-magnesium; and second, to measure LDL-cholesterol in the supernatant by the homogeneous method or apolipoprotein B (apoB) by an immunoturbidometric assay. The cholesterol and apoB values obtained by the precipitation method (45 +/- 26 and 33 +/- 20 mg/dl, respectively) were similar to those obtained in the lipoprotein (d = 1.044-1.063) separated by ultracentrifugation (42 +/- 22 and 31 +/- 17 mg/dl, respectively), and there was an excellent correlation between the two methods for sd LDL-cholesterol (y = 1.05X + 1, r = 0.88, n = 69) and apoB (y = 1.07X, r = 0.90). Sd LDL values had a significant inverse correlation with LDL size. A high correlation was found between sd LDL-cholesterol and apoB values (r = 0.94). Sd LDL value was related to triglyceride, apoB, and LDL-cholesterol, but not to the buoyant LDL level. These results suggest that this precipitation method is a simple and rapid method for the measurement of sd LDL concentration.

An evaluation of pharmaceutical treatment of dyslipidaemia among patients without diagnosed atherosclerotic disease in Belgium

The aim of this study was to assess the lipoprotein levels in patients without diagnosed atherosclerotic disease but treated with lipid-lowering drugs. During February and March 2002 all demands for continuation of reimbursement of lipid-lowering drugs were recorded at two regional offices of health insurance associations. A total of 1973 patients without diagnosed atherosclerotic disease were included (mean age 66 years). Mean total cholesterol (TC) was 5.39 mmol/l, high-density lipoprotein cholesterol (HDL-C) 1.50 mmol/l, low-density lipoprotein cholesterol (LDL-C) 3.16 mmol/l and triglycerides (TG) 1.59 mmol/l. Thirty-four per cent of the treated patients reached the TC target of 5.0 mmol/l or less. The LDL-C target level of 3.0 mmol/l or less was reached by 45% of the patients. Of the patients receiving a statin, 61% were not treated with the optimal doses. The treatment was adjusted in 15% of the patients who did not reach the combined endpoint.

A novel genetic variant in the apolipoprotein A5 gene is associated with hypertriglyceridemia

The apolipoprotein A5 gene (APOA5 ) has been shown to play an important role in determining plasma triglyceride concentrations in humans. We describe here a novel variant, c.553G>T, in the apolipoprotein A5 gene that is associated with hypertriglyceridemia. In contrast to some other polymorphisms, which occur in non-coding regions of the gene, this variant occurs within the coding region and causes the change of amino acid sequence (a substitution of a cysteine for a glycine residue). The minor allele frequencies were 0.042 and 0.27 (P<0.001) for control and hypertriglyceridemic patients, respectively. The serum triglyceride level was significantly different among the genotypic groups (G/G 92.5+/-37.8 mg/dl, G/T 106.6+/-34.8 mg/dl, T/T 183.0 mg/dl, P=0.014) in control subjects. Multiple logistic regression revealed individuals carrying the minor allele had age, gender and BMI (body mass index)-adjusted odds ratio of 11.73 (95% confidence interval of 6.617-20.793; P<0.0001) for developing hypertriglyceridemia in comparison to individuals without that allele. These findings suggest the possible use of c.553G>T polymorphisms in APOA5 as prognostic indicators for hypertriglyceridemia susceptibility in Chinese.

PON1 activities and oxidative markers of LDL in patients with angiographically proven coronary artery disease

BACKGROUND

There is growing evidence that ox-LDL plays an important role during the atherosclerosis process and PON1 can significantly inhibit generation of lipid peroxidation during LDL oxidation and thus play a role in the in vivo protection by HDL against atherosclerosis.

METHODS

Twenty-four healthy volunteers and one-hundred and one patients were taken into study, sixty-eight patients had coronary artery disease which was confirmed by coronary angiography. Serum PON1, erythrocyte superoxide dismutase and catalase activities, oxidative markers of LDL were determined along with the routine biochemical parameters in all groups.

RESULTS

The indicators of oxidative stress were higher in the patients compared with the controls. No statistically significant difference in any of parameters were observed between the patients who had obstruction with different degrees except for erythrocyte TBARS [24.5 nM/g Hb in patients with one vessel disease (VD) (n=22), 29.6 nM/g Hb in patients with two VD (n=26) and 33.5 nM/g Hb in patients with three VD (n=20)]. Basal and stimulated diene levels were higher in patients who had more diseased vessels than those who had less.

CONCLUSION

The increase in erythrocyte TBARS and CRP levels with the severity of disease supports the reports that showed the inflammatory and oxidative nature of atherosclerosis. In the light of the fact that the well-known classical risk factors for atherosclerosis are closely associated with increased oxidative stress, we propose that the elevation in TBARS levels might be a more marked indicator for the degree of atherosclerosis than the insufficiency in antioxidant enzymes such as SOD and PON1.

Update on the National Cholesterol Education Program Adult Treatment Panel III Guidelines: Getting to Goal

Considerable data on the pathophysiology, epidemiology, and treatment of dyslipidemia-induced coronary heart disease (CHD) have accumulated in recent years. These data have been assessed and incorporated into the guidelines of the National Cholesterol Education Program Expert Panel on the Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel [ATP] III). A major focus of the new guidelines is the assessment of the near-term (i.e., 10-yr) risk of experiencing a CHD event and matching the intensity of treatment to this risk. Patients with diabetes and those with a greater than 20% 10-year risk of experiencing a CHD event have been elevated to the risk level of CHD equivalent. The ATP III guidelines also modify several lipid and lipoprotein classifications. A low-density lipoprotein cholesterol (LDL) level below 100 mg/dl is now considered optimum for all individuals. In addition, high-density lipoprotein cholesterol (HDL) and triglyceride cutoff points have been modified to reflect more accurately the risk associated with abnormalities in these lipoproteins. As with the previous guidelines, the primary target of therapy remains LDL. Therapeutic lifestyle changes consisting of diet, weight reduction, and increased physical activity should be included in all treatment regimens. Based on their potent LDL-lowering properties and their proven ability to decrease mortality in a variety of patient populations, statins are generally the first choice for pharmacologic therapy. A secondary target of therapy includes non-HDL goals for patients with high triglyceride levels and the metabolic syndrome, which is characterized by abdominal obesity, elevated triglyceride levels, low HDL levels, and insulin resistance. Management of these secondary targets includes weight reduction and increased physical activity, and treatment of the lipid and nonlipid risk factors. Overall, ATP III represents an aggressive approach to treating dyslipidemia, greatly extending the number of individuals who qualify for treatment.

Plasma lipid modifications in elderly people after administration of two virgin olive oils of the same variety (Olea europaea var. hojiblanca) with different triacylglycerol composition

In the present study we examined whether two virgin olive oils (VOO1 and VOO2), of the same variety (Olea europaea var. hojiblanca with a similar composition of minor components but differing in the content of triacylglycerol molecular species, had different effects on blood pressure and plasma lipid levels in a healthy elderly population. Thirty-one participants, aged 84-9 (SD 6.4) years, were asked to participate in the study. No differences were found with regard to blood pressure after both experimental periods (VOO1 and VOO2). However, plasma total cholesterol and LDL-cholesterol were reduced only after VOO1 (P<0.01). The reduction of plasma cholesterol concentrations was related to the incorporation of oleic acid into plasma cholesteryl esters and phospholipids strongly correlated with plasma total cholesterol and LDL-cholesterol levels in all experimental periods studied (r2>0.418, P<0.07), except for phospholipids in VOO1 (P=0.130 for total cholesterol and p=0.360 for LDL-cholesterol). These results have demonstrated that blood pressure and plasma lipids can be modified by the consumption of VOO in elderly people, but that the extent of such modification depends on the composition and amount of active minor components and triacylglycerol molecular species.

Effect of the microsomal triglyceride transfer protein -493 G/T polymorphism and type 2 diabetes mellitus on LDL subfractions

Genetic variation in the microsomal triglyceride transfer protein (MTP) affects the secretion pattern and plasma concentration of apolipoprotein (aopB)-containing lipoproteins and a common functional -493 G/T polymorphism has been reported to influence plasma lipids levels. Recent data suggest that carriers of the T allele might be more sensitive to detrimental factors such as features of the insulin resistance syndrome. Since type 2 diabetes is associated with obesity and insulin resistance, the present study investigated the effect of this polymorphism on plasma lipids, apoB and LDL subfractions in 281 Chinese type 2 diabetic subjects and 364 non-diabetic controls. The frequency of the rare T allele was 0.162 and 0.126 in subjects with and without diabetes respectively. There were no differences in the effect of the polymorphism on plasma lipids and apoB in the two groups. However, the TT genotype was associated with a higher concentration of small dense LDL-III than the GT or GG variants in the diabetic subjects (P=0.01) whereas no such effect was observed in the controls. In the diabetic patients, age, plasma triglyceride and the MTP genotype were independent determinants of LDL-III concentrations in linear regression analysis (R(2)=10%, P=0.04) whereas in the controls, only plasma triglyceride and age were important determinants (R(2)=15%, P=0.01). In conclusion, the -493 G/T polymorphism only has a minor effect on LDL subfraction pattern in Chinese and the effect is only apparent in the presence of type 2 diabetes.

Multinucleated variant endothelial cells (MVECs) have a greater capacity for LDL cholesterol uptake than typical mononuclear endothelial cells (TECs)

The existence of large endothelial cells in the human aorta, especially on atherosclerotic lesions has been reported. They have multiple nuclei and are called "multinucleated variant endothelial cells (MVECs)". In the present study caveolin expression was demonstrated in both MVECs and small typical endothelial cells (TECs). Caveolin was expressed diffusely as fine particles, and caveoles were expressed as prominent accumulations of caveolin in the cytoplasm. LDL was bound to the endothelial surface. With double immunostaining for caveolin and LDL, the location of LDL corresponded to the immunoreactive caveoles. Over time, large dots of LDL appeared in MVECs, whereas a few fine particles remained in TECs. An electron microscopic chase study of LDL-gold uptake identified many LDL-gold particles in plasmalemmal vesicles and in endosomes or lysosomes of MVECs, but only a few particles were found in TECs. Gold containing vesicles often were located near the abluminal surface. The number of LDL-gold particles was 4.5 times greater per unit area in MVECs than in TECs. Some of the gold particles were located in the subendothelial collagen matrix. These findings indicate that MVECs have a greater capacity of LDL cholesterol uptake followed by transport to the subendothelial matrices than TECs, and that MVECs contribute to the development and advancement of atherosclerotic lesions.

A randomized controlled trial of a public health nurse directed treatment program for rural patients with high blood cholesterol

BACKGROUND

Many rural residents do not have access to high-quality nutrition counseling for high blood cholesterol. The objective of this study was to assess the effectiveness of an intervention program designed to facilitate dietary counseling for hypercholesterolemia by rural public health nurses.

METHODS

Eight health departments (216 participants) were randomized to give the special intervention (SI) and nine (252 participants) to give the minimal intervention (MI). The SI consisted of three individual diet counseling sessions given by a public health nurse, using a structured dietary intervention (Food for Heart Program), referral to a nutritionist if lipid goals were not achieved at 3-month follow-up, and a reinforcement phone call and newsletters. Diet was assessed by the Dietary Risk Assessment (DRA), a validated food frequency questionnaire, at baseline, 3-, and 12-month follow-up; blood lipids and weight were assessed at baseline, 3-, 6-, and 12-month follow-up.

RESULTS

Participants were largely female (71%), older (mean age 55), and white (80%). At 3-month follow-up, the average reduction (indicating dietary improvement) in total Dietary Risk Assessment score was 3.7 units greater in the SI group (95% confidence interval [CI] 1.9 to 5.5, P = 0.0006), while both groups experienced a similar reduction in blood cholesterol, 14.1 mg/dL (0.37 mmol/L) for SI and 14.5 mg/dL (0.38 mmol/L) for minimal intervention group (difference -0.4 mg/dL [-0.010 mmol/L], 95% CI -12.5 to 11.7 [-0.32 to 0.30], P = 0.9). At 12-month follow-up, the reduction in total Dietary Risk Assessment score was 2.1 units greater in the SI group (95% CI 0.8 to 3.5, P = 0.005), while the reduction in blood cholesterol was similar in both groups, 18.4 mg/dL (0.48 mmol/L) for SI and 15.6 mg/dL (0.40 mmol/L) for minimal intervention group (difference 2.8 mg/dL [0.07 mmol/L], 95% CI -7.5 to 13.1 [-0.19 to 0.34], P = 0.6). During follow-up, weight loss was greater in the SI group; the difference between groups was statistically significant at 3 (1.9 lb [0.86 kg], 95% CI 0.3 to 3.4 [0.14 to 1.55], P = 0.022) and 6 months (2.1 lb [0.95 kg], 95% CI 0.1 to 4.1 [0.04 to 1.86], P = 0.04). At 12 months, the difference was not significant (1.6 lb [0.73 kg], 95% CI -0.05 to 3.7 [-0.02 to 1.68], P = 0.13).

CONCLUSIONS

Improvement in self-reported dietary intake was significantly greater in the SI group, while reduction in blood cholesterol was similar in both groups.

LDL apheresis

Low density lipoprotein (LDL) apheresis provides a safe and effective means of treating patients with homozygous familial hypercholesterolaemia (FH). It also has a role in preventing the progression of coronary artery disease in heterozygotes and others with severe dyslipidaemia who are refractory to or intolerant of high doses of lipid-lowering drugs. Established methods involve either adsorption of apolipoprotein B-containing lipoproteins by affinity columns containing anti-apolipoprotein B antibodies or dextran sulphate, or their precipitation at low pH by heparin, in each instance after first separating plasma from blood cells with a cell separator. The most recently developed method enables lipoproteins to be adsorbed directly from whole blood, using polyacrylate columns. All 4 methods have proved to be similarly efficient when used weekly or biweekly to lower LDL cholesterol and Lp(a) without unduly reducing HDL cholesterol. Economic constraints restrict the use of LDL apheresis to the treatment of potentially fatal disorders such as FH, where there is clear evidence of benefit compared with conventional therapy. Widening the indications to include the treatment of other dyslipidaemic disorders such as steroid-resistant nephrotic syndrome, post-transplant donor vessel disease, stroke and prevention of re-stenosis after coronary angioplasty requires evidence from controlled trials that is currently lacking.

Effects of atorvastatin on electrophoretic characteristics of LDL particles among subjects with heterozygous familial hypercholesterolemia

The effects of the HMG CoA reductase inhibitor atorvastatin on electrophoretic characteristics of LDL particles were evaluated in 46 patients (28 males and 18 females) with heterozygous familial hypercholesterolemia (FH) aged 20-61 carrying either a negative or a defective LDL receptor gene mutation. Following a 6 week drug-free baseline period, FH heterozygotes were treated with atorvastatin (median dose: 20 mg/day, range 10-80 mg/day)) for 6 months to maintain their plasma LDL-cholesterol concentrations between 4.0 and 5.0 mmol/l. Atorvastatin treatment significantly reduced plasma total cholesterol, LDL-cholesterol and triglyceride levels and increased plasma HDL-cholesterol. Furthermore, atorvastatin treatment significantly increased LDL peak particle diameter (LDL-PPD) by 0.5% (from 255.0+/-6.2 to 256.4+/-5.5 A, P=0.004) and reduced the absolute concentration of cholesterol among small (<255 A) and large (>260 A) LDL particles by 35% (P<0.001). Changes in LDL-PPD and plasma triglyceride levels were inversely correlated (R=-0.34; P=0.02). Stepwise multiple linear regression analyses showed that 41.6% of the variation in the LDL-PPD response to atorvastatin was attributable to the initial LDL-PPD (14.4%, P=0.003), the apo E polymorphism (12.4%, P=0.02), the nature of the LDL receptor gene mutation (9.6%, P=0.01) and change in triglyceride levels (5.2%, P=0.04). Moreover, the reduction in the cholesterol content of LDL <255 A was directly correlated with the daily dosage of atorvastatin (P=0.05). Results of the present study showed that atorvastatin alters significantly LDL heterogeneity in patients at high risk of coronary heart disease (CHD) such as FH heterozygotes. These results also suggest that genetic and metabolic factors may be important determinants of atorvastatin-induced changes of LDL particle size and distribution among FH heterozygotes.

Fatty acid abnormalities in chronic pancreatitis: effect of concomitant diabetes mellitus

OBJECTIVE

Patients with chronic pancreatitis suffer from malabsorption and nutritional deficiencies. However there is little data available concerning the fatty acid profile in chronic pancreatitis. Diabetes mellitus, a common complication of this disease, could interfere with the metabolism of fatty acids.

SUBJECTS

We therefore compared the fatty acid composition of LDL from four groups of male patients with (a) chronic pancreatitis without diabetes (ND-CP; n=12), (b) diabetes secondary to chronic pancreatitis and insulin-treated (CP-D; n=35); (c) type 1 diabetes (n=25); and (d) controls (n=20).

RESULTS

The patients in both groups of chronic pancreatitis (ND-CP and CP-D) had lower mean values for linoleic acid than that seen in the type 1 DM and control groups, whereas monounsaturated fatty acids (MUFA; 18 : 1(n-9) and (16 : 1(n-7)) were significantly increased in these two groups (ND-CP and CP-D). Docosa-hexaenoic-acid (22 : 6(n-3)) was significantly decreased in the CP-D group (P>0.05), a response that could be explained by the effects of diabetes mellitus and by selenium deficiency. In this way, diabetes was associated with a decrease in the docosa-hexaenoic-acid (22 : 6(n-3); r=0.30, P=0.005), and selenium was correlated with DHA (r=0.28, P=0.029) and with the 22 : 6(n-3)/20 : 5(n-3) ratio (evaluating the delta 4 desaturation); r=0.31, P=0.022), independently of the diabetes effect. Selenium was negatively correlated with 20 : 4(n-6)/20 : 3(n-6) ratio (evaluating the delta 5 desaturase; r=-0.30; P=0.025). These results suggest that these two factors may have a role in the regulation of the desaturation process. If we consider that a ratio of 16 : 1(n-7)/18 : 2(n-6) greater than 0.086 in plasma indicates an EFAn-6 deficiency, 40% of our CP patients, 57.6% of CP-D patients and 13.6% of type 1 DM patients were involved.

CONCLUSIONS

The consequences of these deficiencies are not evaluated in this disease. However, correction of the fundamental deficiencies in essential fatty acids and in selenium seems desirable in chronic pancreatitis.

Effect of plasma C-reactive protein levels in modulating the risk of coronary heart disease associated with small, dense, low-density lipoproteins in men (The Quebec Cardiovascular Study)

This purpose of this study was to investigate how plasma C-reactive protein (CRP), a nonspecific acute-phase reactant, modulates the risk of coronary heart disease (CHD) associated with the small, dense, low-density lipoprotein (LDL) phenotype. LDL particle size and plasma CRP were measured in the Quebec Cardiovascular Study cohort of 2,025 men free of CHD at baseline, among whom 103 had a first CHD event during a 5-year follow-up period. Plasma CRP levels were measured using the Behring Latex-Enhanced (highly sensitive) CRP assay. LDL particle size phenotype was characterized using 2% to 16% polyacrylamide gradient gel electrophoresis. There were weak but significant associations between plasma CRP levels and features of LDL size, such as the proportion of LDL with a diameter <255 A (r = 0.09, p <0.001) and LDL peak particle size (r = -0.09, p <0.001). Variations in plasma CRP levels modulated the risk of CHD associated with small LDL peak particle size (relative risk 4.3 vs 2.5 in men with high vs low plasma CRP levels, respectively) and with an elevated proportion of LDL <255 A (relative risk 6.6 vs 3.0). Thus, increased plasma CRP levels further elevate the risk of CHD associated with having small, dense LDL particles.

Quantitative Analysis of Apolipoprotein E Secretion by Human Monocyte-Derived Macrophages in Culture

Apolipoprotein E (apo E) has an impact on lipid metabolism and its production by macrophages is considered to play a protective role against atherosclerosis. Apo A-I stimulates secretion of apo E from macrophages. We developed a new method to evaluate the ability of human monocyte-derived macrophages to secrete apo E, and the effects of factors such as apo A-I were examined. Monocytes separated from peripheral venous blood were cultured. The levels of apo E in macrophage-conditioned medium were quantified by immunoblotting with an anti-human apo E antiserum conjugated with alkaline phosphatase. The basal levels of apo E secretion and the response to exogenous apo A-I in macrophages from 10 healthy volunteers were measured. Sufficient accuracy and sensitivity were confirmed and coefficient of variation of the method was 18 +/- 11% (n = 10). It was confirmed that macrophage secreted apo E in a concentration-dependent manner in response to M-CSF and apo A-I. The average apo E concentration in the conditioned medium of macrophages from 10 healthy subjects was 30.9 +/- 14.7 ng/mg cell protein. After the addition of apo A-I, the average apo E concentration increased, by about 60%, to 49.4 +/- 29.7 ng/mg cell protein (p < 0.05). There was a positive correlation between the apo A-I-induced increase and plasma LDL cholesterol levels (r = +0.54, p < 0.05).

Effects of soy and other natural products on LDL:HDL ratio and other lipid parameters: a literature review

Abnormal lipid levels contribute significantly to the risk of coronary heart disease, a major cardiovascular disease and a serious health problem. Various dietary and pharmacologic treatments have been devised to reduce elevated blood cholesterol levels. Soy protein, soluble fiber, and plant sterol/ester-containing margarines are promising new food-component candidates that may help to realize this goal. Of particular interest in this context is the LDL:HDL ratio, a strong predictor of cardiac events. This report is a review of more than 50 recent trials to determine how such dietary components and garlic affect the LDL:HDL ratio and other lipid parameters. Consumption of new soy products containing high, fixed levels of isoflavones, cotyledon soy fiber, and soy phospholipids (Abaco and Abalon) significantly reduced the LDL:HDL ratio by up to 27%. Soluble dietary fibers such as psyllium and beta glucan from oat bran had a variable effect on LDL-cholesterol levels in the studies analyzed. Plant sterol esters, when consumed in margarines, lowered the LDL:HDL ratio by up to 22%. On average, Abacor and Abalon reduced the LDL:HDL ratio by 20%, LDL cholesterol by 15%, total cholesterol by 10%, and triglycerides by 6%, and increased HDL cholesterol by 5%. The new soy-based supplements may therefore play a valuable role in reducing cardiovascular risk.

Diabetes, plasma insulin, and cardiovascular disease: subgroup analysis from the Department of Veterans Affairs high-density lipoprotein intervention trial (VA-HIT)

BACKGROUND

Diabetes mellitus, impaired fasting glucose level, or insulin resistance are associated with increased risk of cardiovascular disease.

OBJECTIVES

To determine the efficacy of gemfibrozil in subjects with varying levels of glucose tolerance or hyperinsulinemia and to examine the association between diabetes status and glucose and insulin levels and risk of cardiovascular outcomes.

METHODS

Subgroup analyses from the Department of Veterans Affairs High-Density Lipoprotein Intervention Trial, a randomized controlled trial that enrolled 2531 men with coronary heart disease (CHD), a high-density lipoprotein cholesterol level of 40 mg/dL or less (</=1.04 mmol/L), and a low-density lipoprotein cholesterol level of 140 mg/dL or less (</=3.63 mmol/L). Subjects received either gemfibrozil (1200 mg/d) or matching placebo and were followed up for an average of 5.1 years. In this article, we report the composite end point (CHD death, stroke, or myocardial infarction).

RESULTS

Compared with those with a normal fasting glucose level, risk was increased in subjects with known diabetes (hazard ratio [HR], 1.87; 95% confidence interval [CI], 1.44-2.43; P =.001) and those with newly diagnosed diabetes (HR, 1.72; 95% CI, 1.10-2.68; P =.02). In persons without diabetes, a fasting plasma insulin level of 39 micro U/mL or greater (>/=271 pmol/L) was associated with a 31% increased risk of events (P =.03). Gemfibrozil was effective in persons with diabetes (risk reduction for composite end point, 32%; P =.004). The reduction in CHD death was 41% (HR, 0.59; 95% CI, 0.39-0.91; P =.02). Among individuals without diabetes, gemfibrozil was most efficacious for those in the highest fasting plasma insulin level quartile (risk reduction, 35%; P =.04).

CONCLUSION

In men with CHD and a low high-density lipoprotein cholesterol level, gemfibrozil use was associated with a reduction in major cardiovascular events in persons with diabetes and in nondiabetic subjects with a high fasting plasma insulin level.

Results from EuCliD (European Clinical Dialysis Database): impact of shifting treatment modality

BACKGROUND

The use of biocompatible high-flux membranes is more efficient than low-flux membranes in controlling a number of hemodialysis-related diseases. The aim of this cooperative study was to evaluate the 6-month effect of a switch from low- to high-flux dialysers on patients treated in 39 Spanish dialysis centres.

METHODS

The clinical data used in this analysis were prospectively collected by the EuCliD database, developed to monitor the quality of treatment delivered in a large network of European Dialysis Centres. Inclusion criteria for the study were the condition of end-stage renal disease (ESRD) on chronic hemodialysis and low-flux dialysis for at least six months before the switch to high-flux dialysis. Of 1,543 patients enrolled in the study between 2000 and 2001, 1,046 patients were considered for the analysis. 497 patients were excluded because they did not complete the follow-up. Outcome measures were the reduction of pre-dialysis beta-2 microglobulin, the improvement of anemia or reduction in rHu-EPO dose required to maintain best correction of anemia, reduction of inflammatory parameters (CRP), improvement in lipid profile (Total and HDL cholesterol, tryglycerides), maintenance of nutritional status. Albumin and "dry" (post-hemodialysis) body weight were both evaluated as nutritional indexes.

RESULTS

During the six months of high-flux hemodialysis, there was a significant increase in hemoglobin (from 11.55 +/- 1.41 to 11.88 +/- 1.43 g/L; p < 0.001). Considering the temporarily untreated patients on a 0 U/week dose, erythropoietin remained stable (from 5,670 +/- 4,199 to 5,657 +/- 4,411 U/week). During the second part of the follow-up, the lipid profile significantly improved (Fig. 3). Total cholesterol and triglycerides decreased significantly (p < 0.001), while HDL cholesterol increased (p = 0.006). Calculated levels of LDL cholesterol also significantly decreased (p = 0.001). Dry body weight remained stable (64.7 +/- 11.9 vs. 64.7 +/- 12.0 kg) as well as in albumin levels (3.93 +/- 0.43 vs. 3.94 +/- 0.43 g/dL) between the two modalities of treatment. The level of beta2-microglobulin significantly decreased during high-flux dialysis (33.5 +/- 14.4 vs. 26.3 +/- 8.6 mg/dL, p < 0.001).

CONCLUSION

All above mentioned results may have as a common denominator an improved blood purification from uremic toxins and a reduced level of chronic sub-clinical inflammation. All together, these results seem to confirm the superiority of high-flux dialysis in terms of clinical and physiological outcomes.

How should low-density lipoprotein cholesterol concentration be determined?

The National Cholesterol Education Program Adult Treatment Panel III Report (NCEP-ATP III) has identified low-density lipoprotein cholesterol (LDLC) as the primary target of therapy and has recommended using the Friedewald calculated LDL-C (CLDL- C). The present study compared a direct LDLC (D-LDL-C) method with the C-LDL-C and determined the possible impact on treatment decisions. C-LDL-C and D-LDL-C were compared in 464 consecutive patients. The D-LDL-C was 18% higher than the C-LDL-C at 100 mg/dL, an important level for medical decision making. This can result in inappropriate drug therapy (usually overtreatment) if the NCEP-ATP III treatment guidelines are followed with the D-LDL-C rather than the C-LDL-C. The C-LDL-C is preferred because this assay has been used in clinical trials documenting the benefits of cholesterol-lowering therapy.

Association of body mass index and health status in firefighters

This study evaluates the usefulness of body mass index (BMI) as a preventive screening tool for general health and duty fitness status among firefighters. Two major BMI categorization methods were used: (1) "standard" [low (< 27), medium (> or = 27 < 30), high (> 30)]; and (2) WHO [(normal (< 25), overweight (> or = 25 < 30), obese (> or = 30 < 39), morbidly obese (> or = 39)]. Using the "standard" categorization, nearly 60% of individuals had medium or high BMI's; using the World Health Organization categorization, 80.7% of individuals were found to be overweight, obese, or morbidly obese. Statistically significant, inverse correlation between BMI and each of the following parameters was noted: systolic and diastolic blood pressure, VO2max, METS, and total cholesterol. Inconsistent or statistically insignificant correlation was found between BMI and HDL, Chol/HDL ratio, triglycerides, FVC% predicted, and FEV1 second% predicted. Findings were similar to previous studies of such correlates. BMI continues to prove useful as a screening tool and may be useful in identifying individual firefighters for health and fitness intervention measures.

Intimal plaque development and oxidative stress in cholesterol-induced atherosclerosis in New Zealand rabbits

Although oxidative stress is well known in atherogenesis, the origin, nature and kinetics of free radicals involved have not been well described till now. Here, we correlated parameters of oxidative stress with cellular components during induction and stabilization of aortic intimal lesions which were induced in rabbits by feeding a cholesterol-enriched diet for 6 weeks and a normal diet for further 68 weeks. Plasma lipids, aortic plaque size and composition (macrophages, smooth muscle cells, oxidized LDL by morphometry), as well as aortic radical production (by luminol-enhanced chemiluminescence and TEMPO-9AC fluorescence) were measured after various time points. The parameters of oxidative stress were correlated with the different cellular components of the aortic plaques. The plaques increased until week 21, no significant regression was found until week 74, plasma cholesterol was maximal at week 6. Macrophages, oxidized LDL and generation of different species of free radicals were increased during plaque development, yet with different time kinetics. Whereas chemiluminescence correlated only weakly with the amount of intimal macrophages, strong correlations were found between TEMPO fluorescence and smooth muscle cells (r = 0.4778, P < 0.001) and between macrophages and oxidized LDL (r = 0.5896, P < 0.0001). Different indicators of oxidative stress were increased during plaque progression and stabilization. However, the various correlations show, that distinct types of reactive species secreted probably from macrophages and smooth muscle cells contribute to oxidative stress in the different phases of plaque development.

Specialized lipid profiles

Individuals with abnormal blood lipids and lipoproteins are at increased risk for cardiovascular disease. With the development of effective dietary, behavioral, and pharmaceutical treatments to optimize blood lipoproteins, accurate clinical assessment of blood lipids and lipoproteins are essential for patient management and research. This article discusses the use of a variety of lipid analyses currently available. The use of traditional lipoprotein measurements, including Friedewald calculation of low-density lipoprotein (LDL) cholesterol and ultracentrifugation methods to measure blood lipoproteins, are discussed. Newer analytic techniques, including the vertical analytic profile, nuclear magnetic resonance, direct LDL measurement, LDL size determination, and triglyceride-rich lipoprotein remnants, are also described. Despite the development of a number of lipid and lipoprotein assays, lipoprotein analysis with a Friedewald- calculated LDL measurement remains the lipoprotein analysis performed in approximately 93% of clinical laboratories. It remains to be determined if the alternative lipid and lipoprotein assays currently available will become more widely utilized in the future.

Flaxseed dietary supplement versus hormone replacement therapy in hypercholesterolemic menopausal women

OBJECTIVE

To assess serum lipid changes by a phytoestrogen dietary supplement compared with oral estrogen-progesterone replacement in hypercholesterolemic menopausal women.

METHODS

Twenty-five menopausal patients with total cholesterol greater than 6.2 mmol/L (240 mg/dL), a cholesterol/high-density lipoprotein-cholesterol ratio greater than 4.5 and triglycerides less than 3.5 mmol/L (310 mg/dL) after a 4-month diet, were randomized to add 40 g/day of crushed flaxseed to their diet or to take daily 0.625 mg of conjugated equine estrogens alone (hysterectomy, n = 10) or combined with 100 mg of micronized progesterone (intact uterus, n = 15). After 2 months of treatment, both groups continued the diet alone during a 2-month washout period before crossing over to the alternate treatment for 2 more months.

RESULTS

Differences were found between hormone replacement therapy and flaxseed respectively for decrease of low-density lipoprotein cholesterol (3.8 +/- 0.2 versus 4.4 +/- 0.2 mmol/L) (148 +/- 8 versus 170 +/- 8 mg/dL) (P =.10), increase of high-density lipoprotein cholesterol (1.6 +/- 0.04 versus 1.3 +/- 0.03 mmol/L) (62 +/- 1 versus 50 +/- 1 mg/dL) (P =.001), and increase of apolipoprotein A-1 (1.71 +/- 0.07 versus 1.42 +/- 0.05 g/L) (P =.003). These changes were not related to modifications in diet, exercise, or anthropometric measurements evaluated in parallel. Both treatments produced similar decreases in menopausal symptoms and in glucose and insulin levels. Only hormone replacement therapy as compared with flaxseed induced an elevation of sex hormone binding globulin (P =.004), lowered fibrinogen (P =.08), and plasminogen activator inhibitor type 1 (P =.01).

CONCLUSION

Although 40 g of flaxseed is as effective as oral estrogen-progesterone to improve mild menopausal symptoms and to lower glucose and insulin levels, only hormone replacement therapy significantly improves cholesterol profile in hypercholesterolemic women and favorably modifies markers related to cardiovascular health.

Oxidized LDL metabolites with high family risk for premature cardiovascular disease

OBJECTIVE

Considering the importance of primary prevention of Cardiovascular Disease (CVD) from childhood, especially in children with high family risk for premature atherosclerosis, and also the importance of oxidized LDL in the process of atherosclerosis, the main metabolites of ox-LDL i.e. Malondialdehyde (MDA) and Conjugated diene (CDE) have been measured in children of high risk families and compared with a control group.

METHODS

Children and adolescents (6-18 years) of parents with premature myocardial infarction (MI < or = 55 y in men and < or = 65 y in women), were selected as the case group. The control group included neighbors of the case group matched for age and socioeconomic status. All samples have been selected by simple random sampling. Both the case and control groups were divided in two subgroups: those with a total cholesterol and/or LDL-C > or = 95th centile and those with normal lipid levels. Each subgroup consisted of 32 subjects, so 128 subjects were studied (64 in the case and 64 in the control group). MDA and CDE were measured by spectrophotometry using molar absorbivity. Data were analyzed by SPSSv10/Win software using ANOVA, Bonferroni, Scheffe-Duncan, Tukey-HSD, and the Student's t-test.

RESULT

The mean MDA value in the case and control groups was significantly different (1.84 +/- 0.43 vs. 1.67 +/- 0.41 micromol/L, p=0.03), but this difference was not significant regarding the mean CDE level (0.50 +/- 0.05 vs. 0.47 +/- 0.04 micromol/L, p>0.05). The mean MDA level in the case group with hyperlipidemia was significantly higher than that in the case group without hyperlipidemia (1.985 +/- 0.516 vs. 1.690 +/- 0.366, micromol/L, P=0.02) and also higher than control group with or without hyperlipidemia (1.985 +/- 0.516 vs. 1.720 +/- 0.389, 1.615 +/- 0.429 micromol/L respectively, P<0.05). The mean CDE level in the case group with hyperlipidemia was significantly higher than the case group without hyperlipidemia (0.542 +/- 0.034 vs. 0.494 +/- 0.049 micromol/L, P=0.04) and higher than the control group with or without hyperlipidemia (0.542 +/- 0.034 vs. 0.464 +/- 0.051, 0.484 +/- 0.048 micromol/L respectively, p<0.05). In case boys with hyperlipidemia, the mean MDA (2.03 +/- 0.2 micromol/L) and the mean of CDE (0.56 +/- 0.04 micromol/L) was significantly higher than other subgroups (P<0.05).

CONCLUSION

Considering the increased susceptibility of LDL to oxidation in children with high family risk for premature CVD, special attention should be paid to consumption of foods and seasoning containing antioxidants from childhood especially in high risk families.

Perspectives: The significance of measuring non-HDL-cholesterol

The third Adult Treatment Panel of the National Cholesterol Education Program has recently issued revised guidelines for the treatment of cholesterol in adults. Increased attention to the metabolic syndrome and diabetes, including the inaccuracy of the low-density lipoprotein cholesterol (LDL-C) measurement in these patients because of elevated triglycerides is highlighted. To overcome the inaccuracy of the Friedewald equation in calculating LDL-C when the triglycerides are elevated, measuring non-high-density lipoprotein (non-HDL-C) may provide a better means to follow these patients toward their treatment goals. Recently, non-HDL-C was shown to be a better predictor of cardiovascular death than LDL-C, even in patients with triglyceride levels below 200 mg/dL. The authors review the basis for using non-HDL-C as a treatment target for cholesterol, in comparison with other lipoproteins.

The importance of lipid evaluation and management in the prevention and treatment of acute myocardial infarction

There is an obvious need to measure low-density lipoprotein cholesterol in all patients with acute myocardial infarction and coronary artery disease. The recent guidelines of the National Cholesterol Education Program have established the desired level for low-density lipoprotein cholesterol for such patients at <100 mg/dL. However, several studies have demonstrated a lack of low-density lipoprotein cholesterol measurement and lipid-lowering therapy with statins in patients with acute myocardial infarction and coronary artery disease. These findings point to a need for quality of care improvement efforts to foster both lipid measurement and statin use in such patients. Many studies have demonstrated the numerous beneficial effects of statin use. In addition to lipid lowering, these include plaque stability and ant platelet, ant macrophage, and antiatherothrombotic activities as well as enhanced endothelial activity. As a class of drugs, the statins have been shown to offer significant benefits with little in the way of associated risks.

Intraindividual variability of children's blood lipid and lipoprotein concentrations: a review

Of the numerous risk factors that have been associated with atherosclerosis and subsequent coronary heart disease, none have caught the public's attention more than plasma cholesterol. An increasing number of studies are focusing on intervention strategies aimed at "improving" the plasma lipid-lipoprotein profile of children. However, the efficacy of these strategies cannot be ascertained unless the biologic and analytic variability of these metabolites has been determined. From the limited available literature, it would appear that the biologic variability of total cholesterol, high- and low-density lipoprotein cholesterol, and triacylglycerol in children is similar to that reported for adults. Yet studies that have directly focused on this important issue with children are scarce, especially those that have included a representative sample and measurements of lipoprotein subfractions. Further research is warranted with children to better establish the extent of intraindividual variation associated with the lipid-lipoprotein profile.

Long-term safety and efficacy of low-fat diets in children and adolescents

The safety and efficacy of low-fat diets in children and adolescents were evaluated through a systematic review of the current literature. Eight major studies were reviewed. The safety of the diets was judged by measures of growth and development and by meeting nutritional requirements. The efficacy of the diets was evaluated by their effect on the plasma levels of total cholesterol and low-density lipoprotein (LDL) cholesterol. All studies except 1 showed that children and adolescents exhibited normal growth and development while on a low-fat diet. In 3 of the studies, nutritional requirements for calcium, zinc, phosphorous and vitamin E were below the recommended daily intake. In each of the 5 studies in which efficacy was determined, a significant decrease in the levels of total or LDL cholesterol was observed. Low-fat diets are generally safe and efficacious when performed under medical supervision.

[Localization of vessel lesions in arteriosclerosis and blood lipid composition]

AIM

To investigate correlations between composition of plasmic lipid fractions in patients with ischemic heart disease (IHD) and those with cerebrovascular insufficiency (CVI) caused by atherosclerosis.

MATERIAL AND METHODS

75 patients were divided into three groups; 26 patients with IHD free of CVI (group 1), 22 patients with CVI free of IHD (group 2), 27 patients with IHD and CVI (group 3). Blood lipids were measured by a standard mesiautomatic method using Technicon-AA-2 unit (USA).

RESULTS

Hyperlipidemia (HLE) type II was most frequent in group 1 while HLE type IV or hypoalphalipoproteinemia without rise in cholesterol or triglycerides--in groups 2 and 3.

CONCLUSION

In IHD without CVI dyslipidemia in most cases was associated with one of the additional risk factors (hypertension, smoking, diabetes mellitus) while in CVI it combined with two or three additional risk factors.