Importance of high-density lipoprotein cholesterol and triglyceride levels in coronary heart disease

PIK3CG single nucleotide polymorphisms are associated with poor responsiveness to clopidogrel and increased risk of ischemia in patients with coronary heart disease

BACKGROUND

This study explores the associations between PIK3CG single nucleotide polymorphisms (SNPs, rs1129293 and rs17398575) and patient responsiveness to clopidogrel to evaluate the risks of ischemia in patients with coronary heart disease (CHD).

METHODS

The study consisted of 513 CHD patients who received clopidogrel as part of antiplatelet therapy, after percutaneous coronary intervention. According to the patient responsiveness to clopidogrel, the subjects were assigned to either clopidogrel-resistant (CR) or clopidogrel-sensitive (CS) groups. CR group was determined by patients' platelet aggregation rate of ≥70% and poor responsiveness to clopidogrel, and CS group by patients' platelet aggregation rates of <70% and good responsiveness to clopidogrel. Polymerase chain reaction using TaqMan probe was employed to detect PIK3CG polymorphism. Haplotype and linkage disequilibrium analyses were performed. Prognosis analysis was performed using the Kaplan-Meier curve.

RESULTS

Significant difference was found in genotype and rs1129293 and rs17398575 allele frequency between the CR and CS groups. Haplotype analysis indicated that the frequency of TG allele was higher in the CR group compared with the CS group, and the frequency of CA allele was lower in the CR group compared with the CS group. Patients with rs1129293 CT + TT genotype and T allele, rs1129293 AG + GG genotype and G allele exhibited an increased CR risk. Logistic regression analysis determined hypertension history as an independent risk factor for CR. The Kaplan-Meier curve suggests that distribution curve of cumulative probability nonischemic events was different between patients with rs1129293 and rs17398575 alleles. Stable CHD patients with TT genotype of rs1129293 allele and GG genotype of rs17398575 allele showed poorer prognosis compared to those with other genotypes and patients with acute coronary syndromes.

CONCLUSION

A positive correlation may exist between PIK3CG SNPs (rs1129293 and rs17398575) and patients with poor responsiveness to clopidogrel. These findings show that this factor may contribute to an increased risk of ischemia in patients suffering from CHD.

Dietary alpha-linolenic acid, EPA, and DHA have differential effects on LDL fatty acid composition but similar effects on serum lipid profiles in normolipidemic humans

Our aim was to study the effects of increased dietary intake of alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), or docosahexaenoic acid (DHA) on serum lipids and LDL fatty acid compositions. To this end, a controlled parallel study was conducted in 74 healthy normolipidemic men and women aged 19-43 y. Participants were randomly assigned to 1 of 3 interventions and consumed a total intake of 4.4 g/d ALA (ALA group), 2.2 g/d EPA (EPA group), and 2.3 g/d DHA (DHA group) for 6 wk. Fatty acid ethyl esters were incorporated into margarines, which replaced the participant's normal spread. The ALA, EPA, or DHA intake led to a significant enrichment of the LDL with the respective (n-3) fatty acid. In addition, LDL EPA contents in the ALA group increased by 36% (P < 0.05) with no changes in LDL DHA. The EPA intervention led to an additional enrichment with DHA (24%; P < 0.001), whereas the DHA intervention further increased the amount of EPA (249%; P < 0.001). ALA, EPA, or DHA intake did not affect fasting serum concentrations of total and LDL cholesterol, but fasting serum triacylglycerol concentrations significantly decreased in the EPA (-0.14 mmol/L) and DHA (-0.30 mmol/L) interventions and also in the ALA intervention (-0.17 mmol/L). DHA intake significantly increased serum HDL cholesterol, whereas no changes were found with ALA or EPA intake. In conclusion, the present data support the hypothesis that isolated dietary ALA, EPA, and DHA intakes lead to differential enrichment in LDL due to interconversion. Moderate amounts of ALA, EPA, and DHA are effective in improving lipid profiles of normolipidemic humans.

Highly sensitive analysis of cholesterol and sitosterol in foods and human biosamples by liquid chromatography with fluorescence detection

A simple and sensitive method is described for the quantitative analysis of important animal and plant sterols (cholesterol and sitosterol) by liquid chromatography with fluorimetric detection. The method is based on the derivatization of cholesterol and sitosterol with a fluorescent reagent (naproxen acyl chloride) in toluene. The resulting derivatives were isocratically separated on a C(8) column with a mixed solvent of methanol-isopropanol-water (90:5:5, v/v) as a mobile phase and monitored with a fluorimetric detector (excitation 231 nm and emission 352 nm). The linear range for the quantitation of cholesterol or sitosterol was 0.1-2.0 microM with a detection limit (S/N=3 with 10 microl injected) of about 25 nM. Recoveries of cholesterol spiked in milk (n=5) ranged over 99-104% with relative standard deviations (RSD) less than 6.0%. Application of the method to the analysis of cholesterol or sitosterol in milk, saliva and urine proved simple and feasible.

Risk of cardiovascular events in patients at optimal values for combined lipid parameters

BACKGROUND

Current prevention guidelines support efforts to achieve optimal high-density lipoprotein (HDL-C) and triglyceride (TG) values, in addition to low-density lipoprotein (LDL-C) in order to reduce cardiovascular (CV) events. The study objective was to evaluate the risk of CV events in patients attaining versus not attaining combined (LDL-C, HDL-C, and TG) optimal lipid values.

METHODS/RESULTS

This retrospective cohort analysis was conducted using a 1.1 million member managed care database. Eligible patients had a full lipid panel between 10/1/99 and 9/30/00, were naive to lipid therapy, and had health plan eligibility 12 months pre- and post-index (baseline) lipid laboratory value. Optimal lipid values (LDL-C, HDL-C, and TG) were established using the National Cholesterol Education Program Adult Treatment Panel (NCEP ATP III) guidelines, and patients were placed into one of four groups: none, one, two, or three lipid components non-optimal at baseline. The presence of cardiovascular risk, disease, and events were determined by selected International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9 CM) and Current Procedural Terminology (CPT codes). The definition of a CV event included: diagnosis of ischemic heart disease, peripheral arterial disease, stroke/TIA, or revascularization procedure. Odds ratios (OR) for a CV event associated with attainment of each optimal lipid fraction were determined by multivariate logistic regression. The study cohort included 30,348 patients, with a mean follow-up of 27 +/- 8 months. Mean age was 66 +/- 12 years; 16,549 (54%) were male; and 17,289 (57%) patients had coronary heart disease (CHD) or CHD risk equivalent. There were 5955 CV events that occurred in 4059 (13%) study patients. The presence of a single non-optimal lipid value slightly increased CV event risk [OR: 1.06; 95% CI: 0.95-1.18], whereas two or all three non-optimal lipid values significantly increased the risk of a CV event [OR: 1.22; 95% CI: 1.08-1.37; and 1.45; 95% CI: 1.24-1.68, respectively].

LIMITATIONS

As with all large observational databases there are potential limitations including: patient selection bias (e.g., more interventions in patients with greater illness, lack of mortality data, and frequency of lipid monitoring), unknown confounding variables, and potential coding errors.

CONCLUSION

Not attaining optimal combined lipid values, independently and significantly, increased the risk of CV events in this large at-risk population with approximately 68,283 patient years of follow-up. The combination of non-attainment of optimal LDL-C with non-attainment of optimal HDL-C or TG values, or both, increased the adjusted risk of CV events by 22-45%. Thus, therapeutic strategies should focus on assessment and management of multiple lipid abnormalities, and not on single lipid risk factor modification.

Metabolic syndrome in adolescents with spinal cord dysfunction

OBJECTIVE

The purpose of this study was to determine the prevalence of components of the metabolic syndrome in adolescents with spinal cord injury (SCI) and spina bifida (SB), and their associations with obesity in subjects with and without SCI and SB.

METHODS

Fifty-four subjects (20 SCI and 34 SB) age 11 to 20 years with mobility impairments from lower extremity paraparesis were recruited from a hospital-based clinic. Sixty able-bodied subjects who were oversampled for obesity served as controls (CTRL). Subjects were categorized as obese if their percent trunk fat measured by dual x-ray absorptiometry (DXA) was > 30.0% for males and > 35.0% for females. Ten SCI, 24 SB, and 19 CTRL subjects were classified as obese. Fasting serum samples were collected to determine serum glucose, insulin, and lipid concentrations. Metabolic syndrome was defined as having > or =3 of the following components: (a) obesity; (b) high-density lipoprotein (HDL) <45 mg/dL for males; <50 mg/dL for females; (c) triglycerides 2100 mg/dL; (d) systolic or diastolic blood pressure > or =95th percentile for age/ height/gender, and (e) insulin resistance determined by either fasting serum glucose 100-125 mg/dL; fasting insulin > or =20 microU /mL; or homeostasis model assessment of insulin resistance > or = 4.0.

RESULTS

Metabolic syndrome was identified in 32.4% of the SB group and 55% of the SCI group. Metabolic syndrome occurred at a significantly higher frequency in obese subjects (SB = 45.8%, SCI = 100%, CTRL = 63.2%) than nonobese subjects (SB = 0%, SCI = 10%, CTRL = 2.4%).

CONCLUSIONS

The prevalence of metabolic syndrome in adolescents with SB/SCI is quite high, particularly in obese individuals. These findings have important implications due to the known risks of cardiovascular diseases and diabetes mellitus associated with metabolic syndrome in adults, particularly those with spinal cord dysfunction.

Lipids and inflammation: serial measurements of the lipid profile of blood donors who later developed rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis is characterised by inflammation and an increased cardiovascular risk. It was recently shown that active early rheumatoid arthritis is associated with dyslipidaemia, which may partially explain the enhanced cardiovascular risk. However, it is unknown when this dyslipidaemia starts.

OBJECTIVE

To investigate the progression of the lipid profile over time and the influence of inflammatory parameters on this lipid profile, in people who later developed rheumatoid arthritis.

METHODS

Levels of total cholesterol, high-density lipoprotein cholesterol (HDLc), triglycerides, apolipoprotein AI (apo AI), apolipoprotein B (apo B) and lipoprotein(a) (Lp(a)) were determined in 1078 stored, deep-frozen, serial blood bank samples, collected between 1984 and 1999, of 79 blood donors who later developed rheumatoid arthritis. These samples were compared with 1071 control samples of unselected blood donors, matched for age, sex and storage time.

RESULTS

Samples of patients who later developed rheumatoid arthritis showed, on average, 4% higher total cholesterol, 9% lower HDLc, 17% higher triglyceride and 6% higher apo B levels than matched controls (p< or =0.05). The magnitude of the differences in lipid levels between groups, explained by C reactive protein (CRP), was limited. For example, only 3.6% of the difference in HDLc levels between the groups was explained by the CRP concentrations.

CONCLUSION

Patients who later develop rheumatoid arthritis have a considerably more atherogenic lipid profile than matched blood donors at least 10 years before onset of symptoms. As inflammation only marginally explains the differences between the two groups, a modulating effect of lipids on inflammatory processes is hypothesised.

Increased disease activity is associated with a deteriorated lipid profile in patients with ankylosing spondylitis

BACKGROUND

Cardiovascular mortality is increased in patients with ankylosing spondylitis. A possible explanation might be a more prevalent atherogenic lipid profile in patients with ankylosing spondylitis than in the general population. It has been postulated that inflammation deteriorates the lipid profile, thereby increasing cardiovascular risk.

OBJECTIVE

To explore the association between disease activity and lipid profile in patients with ankylosing spondylitis.

METHODS

Disease activity parameters for ankylosing spondylitis and lipid levels (total cholesterol, high-density lipoprotein cholesterol (HDLc) and triglycerides) were measured in 45 patients with ankylosing spondylitis for 6 months after starting treatment with leflunomide or placebo. Findings in this treatment group were compared with those in 10 patients with ankylosing spondylitis treated with etanercept. A specialised regression model, adjusting for repeated measurements, age and sex, was used to assess the influence of the disease activity variables on the lipid levels.

RESULTS

Multilevel regression analyses showed significant associations between disease activity parameters and lipid levels-for instance, an increase of 30 mm at the end of the first hour in erythrocyte sedimentation rate was associated with a decrease of about 6% in total cholesterol level and a decrease of about 11% in HDLc levels. Similar significant associations were found between other disease activity parameters and lipid levels.

CONCLUSION

Increase in disease activity was associated with decreases in lipid levels. The decrease in HDLc levels tended to be almost twice as large as the decrease in total cholesterol levels, resulting in a more atherogenic lipid profile. Hence, effective treatment of disease activity in patients with ankylosing spondylitis may lower the cardiovascular risk by improving the lipid profile.

Can foods with added soya-protein or fish-oil reduce risk factors for coronary disease? A factorial randomised controlled trial

BACKGROUND AND AIMS

To develop functional foods which are capable of reducing key risk factors for coronary heart disease in an at risk population. The specific hypothesis tested here was that providing bread, cracker biscuits and snack bars fortified with DHA (long-chain omega 3) and soya-protein would havd a positive impact on cholesterol and blood pressure.

METHODS AND RESULTS

A pragmatic, double-blind, factorial placebo-controlled randomised trial recruiting 213 middle-aged men and women with untreated elevated total cholesterol or blood pressure. The factors examined were the effect of giving supplies of bread, cereal bars and cracker biscuits fortified with 2 g fish oils (DHA, 22: 6n-3), or 25 g soya-protein (containing 50 mg of isoflavonoids) for five weeks. Primary and secondary outcomes included total, low-density and high-density cholesterol (HDL-C), and systolic and diastolic blood pressure. Compliance was assessed using biomarkers and food intake histories. DHA enriched foods increased HDL-C by 6.0% (95% CI 2.5%, 9.6%) but had no effect on total or low-density cholesterol or blood pressure. Overall, soya-protein did not influence any of the outcomes assessed. However, in women only, soya-protein increased systolic blood pressure by 5.9% (95% CI 1.73, 9.9%).

CONCLUSIONS

Adding DHA (fish-oils) to staple foods might supplement existing methods to help reduce CVD morbidity and mortality. However, these findings highlight the importance of ensuring that functional foods do not present any harms to particular subgroups within a general population, if they are to be made freely available to consumers. This latter point requires further attention by the research community in relation to soya-protein.

Individual serum triglyceride responses to high-fat and low-fat diets differ in men with modest and severe hypertriglyceridemia

It is not yet clear whether a low-fat or a high-fat diet is more suitable for the treatment of hypertriglyceridemia. Therefore, we conducted a dietary study with nonobese hypertriglyceridemic men using a randomized crossover design. After a 2-wk acclimation period, the subjects were randomly assigned to 2 groups. One group consumed a low-fat (29% of energy) diet for 3 wk, followed first by a 2-wk washout period, then a 3-wk high-fat (40% of energy) diet period. The second group consumed the low- and high-fat diets in reverse order. Both diets were isocaloric, rich in monounsaturated fatty acids (MUFAs) and long-chain (n-3)-PUFAs, and contained no alcohol. Absolute amounts of long-chain (n-3)-PUFAs and fiber were similar, as were the fatty acid and carbohydrate compositions. Serum triglyceride concentrations in fasting subjects decreased during the high-fat diet period by 34% (95% CI = -19 to -46%, P = 0.001), and during the low-fat diet period by 31% (95% CI = -0.5 to -51.8%, P = 0.048). Triglyceride concentrations did not differ between the low- and high-fat diet periods. However, the high-fat diet lowered triglyceride concentrations more effectively in all subjects with a baseline triglyceride concentration < 4.5 mmol/L, whereas the low-fat diet lowered triglyceride levels more effectively in half of the subjects with a baseline value > 4.5 mmol/L. Based on these findings, we recommend a high-fat triglyceride-lowering diet for patients with only slightly elevated serum triglyceride concentrations (<4.5 mmol/L). However, a lower-fat diet is more suitable for some subjects with more distinctly elevated triglyceride concentrations.