The role of lipoprotein[a] in atherosclerosis

Serum lipoprotein(a) and reclassification of coronary heart disease risk; application of prediction in a cross-sectional analysis of an ongoing Iranian cohort

INTRODUCTION

Recent studies have introduced elevated lipoprotein(a) (Lp(a)) as a risk factor for coronary heart disease (CHD). This study investigated whether the addition of Lp(a) as a novel biomarker to the Framingham Risk Score (FRS) model improves CHD risk prediction.

METHODS

The study included 1101 Iranian subjects (443 non-diabetic and 658 diabetic patients) who were followed for 10 years (2003-2013). Lp(a) levels and CHD events were recorded for each participant.

RESULTS

The Net Reclassification Index (NRI) after adding Lp(a) to the FRS model was 19.57% and the discrimination slope was improved (0.160 vs. 0.173). The Akaike Information Criterion (AIC), a measure of model complexity, decreased significantly after adding Lp(a) to the FRS model (691.9 vs. 685.4, P value: 0.007).

CONCLUSIONS

The study concluded that adding Lp(a) to the FRS model improves CHD risk prediction in an Iranian population without making the model too complex. This could help clinicians to better identify individuals who are at risk of developing CHD and to implement appropriate preventive measures.

Lipoprotein(a) plasma levels are not associated with incident microvascular complications in type 2 diabetes mellitus

AIMS/HYPOTHESIS

Microvascular disease in type 2 diabetes is a significant cause of end-stage renal disease, blindness and peripheral neuropathy. The strict control of known risk factors, e.g. lifestyle, hyperglycaemia, hypertension and dyslipidaemia, reduces the incidence of microvascular complications, but a residual risk remains. Lipoprotein (a) [Lp(a)] is a strong risk factor for macrovascular disease in the general population. We hypothesised that plasma Lp(a) levels and the LPA gene SNPs rs10455872 and rs3798220 are associated with the incident development of microvascular complications in type 2 diabetes.

METHODS

Analyses were performed of data from the DiaGene study, a prospective study for complications of type 2 diabetes, collected in the city of Eindhoven, the Netherlands (n = 1886 individuals with type 2 diabetes, mean follow-up time = 6.97 years). To assess the relationship between plasma Lp(a) levels and the LPA SNPs with each newly developed microvascular complication (retinopathy n = 223, nephropathy n = 246, neuropathy n = 236), Cox proportional hazards models were applied and adjusted for risk factors for microvascular complications (age, sex, mean arterial pressure, non-HDL-cholesterol, HDL-cholesterol, BMI, duration of type 2 diabetes, HbA_1c and smoking).

RESULTS

No significant associations of Lp(a) plasma levels and the LPA SNPs rs10455872 and rs3798220 with prevalent or incident microvascular complications in type 2 diabetes were found. In line with previous observations the LPA SNPs rs10455872 and rs3798220 did influence the plasma Lp(a) levels.

CONCLUSIONS/INTERPRETATION

Our data show no association between Lp(a) plasma levels and the LPA SNPs with known effect on Lp(a) plasma levels with the development of microvascular complications in type 2 diabetes. This indicates that Lp(a) does not play a major role in the development of microvascular complications. However, larger studies are needed to exclude minimal effects of Lp(a) on the development of microvascular complications.

Novel Risk Stratification Assays for Acute Coronary Syndrome

PURPOSE OF REVIEW

Since identification of aspartate aminotransferase as the first cardiac biomarker in the 1950s, there have been a number of new markers used for myocardial damage detection over the decades. There have also been several generations of troponin assays, each with progressively increasing sensitivity for troponin detection. Accordingly, the "standard of care" for myocardial damage detection continues to change. The purpose of this paper is to review the clinical utility, biological mechanisms, and predictive value of these various biomarkers in contemporary clinical studies.

RECENT FINDINGS

As of this writing, a fifth "next" generation troponin assay has now been cleared by the US Food and Drug Administration for clinical use in the USA for subjects presenting with suspected acute coronary syndromes. Use of these high-sensitivity assays has allowed for earlier detection of myocardial damage as well as greater negative predictive value for infarction after only one or two serial measurements. Recent algorithms utilizing these assays have allowed for more rapid rule-out of myocardial infarction in emergency department settings. In this review, we discuss novel assays available for the risk assessment of subjects presenting with chest pain, including both the "next generation" cardiac troponin assays as well as other novel biomarkers. We review the biological mechanisms for these markers, and explore the positive and negative predictive value of the assays in clinical studies, where reported. We also discuss the potential use of these new markers within the context of future clinical care in the modern era of higher sensitivity troponin testing. Finally, we discuss advances in new platforms (e.g., mass spectrometry) that historically have not been considered for rapid in vitro diagnostic capabilities, but that are taking a larger role in clinical diagnostics, and whose prognostic value and power promise to usher in new markers with potential for future clinical utility in acute coronary syndrome.

Relook at lipoprotein (A): independent risk factor of coronary artery disease in north Indian population

AIMS

Lipoprotein (a) [Lp(a)] levels have shown wide ethnic variations. Sparse data on mean Lp(a) levels, its link with clinical variables and severity of coronary artery disease (CAD) in North Indian population needed further studies.

METHODS

150 patients, each of single vessel disease (SVD), double vessel disease (DVD) and triple vessel disease (TVD) with 150 healthy controls were drawn for the study. Serum Lp(a) estimation was performed by immunoturbidimetric method.

RESULTS

Lp(a) had a skewed distribution. Median Lp(a) level was significantly raised in cases as compared to controls (median 30.30 vs. 20 mg/dl, p < 0.001). Cases with acute coronary syndrome (ACS, 55.8%) had significantly higher median Lp(a) levels as compared to those with chronic stable angina (35.4 mg/dl vs. 23 mg/dl, p < 0.001). Significant difference in median Lp(a) levels were observed in patients with DVD or TVD versus control (30, 39.05 vs 20 mg/dl, p < 0.008). Lp(a) level was found to be an independent risk factor for CAD (AOR{adjusted odds ratio} 1.018, 95% CI 1.010-1.027; p < 0.001). Analysis using Lp(a) as categorical variable showed that progressive increase in Lp(a) concentration was associated with increased risk of CAD [AOR from lowest to highest quartile (1, 1.04, 1.43 and 2.65, p value for trend = 0.00026)]. Multivariably AOR of CAD for subjects with Lp(a) in the highest quartile (above 40 mg/dl) compared to those with Lp(a) ≤40 mg/dl was 2.308 (95% CI 1.465-3.636, p < 0.001).

CONCLUSION

Lp(a) above 40 mg/dl (corresponding to 75th percentile)assessed by an isoform insensitive assay is an independent risk factor for CAD. Raised Lp(a) level is also associated with increased risk of ACS and multivessel CAD.

Low-density lipoprotein subfraction, carotid artery intima-media thickness, nitric oxide, and tumor necrosis factor alpha are associated with newly diagnosed ischemic stroke

OBJECTIVES

Small dense (sd) low-density lipoprotein (LDL), tumor necrosis factor (TNF) alpha (α), and nitric oxide (NO) have recently emerged as important stroke risk factors. The aim of the study was to investigate the effects of increased levels of small LDL particle size, TNF-α and NO on the developed ischemic stroke and increased carotid artery intima-media thickness (CIMT).

MATERIALS AND METHODS

A total of 29 women and 25 men (a total of 54 ischemic stroke patients) and a similar age group of 50 controls (29 females and 21 males) were included in the study. CIMT, C-reactive protein (CRP), TNF-α, NO, and lipid subfraction test of the two groups were measured.

RESULTS

The mean LDL particle size was smaller in patients with stroke than in the controls (26.8 ± 0.31 nm vs. 27.0 ± 0.31 nm, P = 0.003). sd-LDL, TNF-α, NO, CRP, right CIMT, and left CIMT were higher in patients with stroke than in the controls (respectively; 8.2 ± 7.8 mg/dL vs. 3.3 ± 3.5 mg/dL, P < 0.001;75.6 ± 25.0 pg/mL vs. 65.4 ± 9.1 pg/mL, P = 0.009;76.4 ± 53.3 mmol/L vs. 41.5 ± 27.0 mmol/L, P < 0.001;1.9 ± 2.6 mm vs. 0.4 ± 0.3 mm P < 0.001;0.97 ± 0.38 mm vs. 0.83 ± 0.15 mm, P = 0.007;1.04 ± 0.44 mm vs. 0.87 ± 0.19 mm, P = 0.010).

CONCLUSION

These results show that sd-LDL is independently associated with the incidence of stroke and may be a risk factor in the development of stroke. In addition, TNF-α, NO, right CIMT, and left CIMT may be a risk factor in the development of ischemic stroke.

Low-density lipoprotein subfraction, carotid artery intima-media thickness, nitric oxide, and tumor necrosis factor alpha are associated with newly diagnosed ischemic stroke

OBJECTIVES

Small dense (sd) low-density lipoprotein (LDL), tumor necrosis factor (TNF) alpha (α), and nitric oxide (NO) have recently emerged as important stroke risk factors. The aim of the study was to investigate the effects of increased levels of small LDL particle size, TNF-α and NO on the developed ischemic stroke and increased carotid artery intima-media thickness (CIMT).

MATERIALS AND METHODS

A total of 29 women and 25 men (a total of 54 ischemic stroke patients) and a similar age group of 50 controls (29 females and 21 males) were included in the study. CIMT, C-reactive protein (CRP), TNF-α, NO, and lipid subfraction test of the two groups were measured.

RESULTS

The mean LDL particle size was smaller in patients with stroke than in the controls (26.8 ± 0.31 nm vs. 27.0 ± 0.31 nm, P = 0.003). sd-LDL, TNF-α, NO, CRP, right CIMT, and left CIMT were higher in patients with stroke than in the controls (respectively; 8.2 ± 7.8 mg/dL vs. 3.3 ± 3.5 mg/dL, P < 0.001;75.6 ± 25.0 pg/mL vs. 65.4 ± 9.1 pg/mL, P = 0.009;76.4 ± 53.3 mmol/L vs. 41.5 ± 27.0 mmol/L, P < 0.001;1.9 ± 2.6 mm vs. 0.4 ± 0.3 mm P < 0.001;0.97 ± 0.38 mm vs. 0.83 ± 0.15 mm, P = 0.007;1.04 ± 0.44 mm vs. 0.87 ± 0.19 mm, P = 0.010).

CONCLUSION

These results show that sd-LDL is independently associated with the incidence of stroke and may be a risk factor in the development of stroke. In addition, TNF-α, NO, right CIMT, and left CIMT may be a risk factor in the development of ischemic stroke.

Lipoprotein (A): Better assessor of coronary heart disease risk in south Indian population

In an attempt to search for risk factors which can explain the increasing prevalence of coronary heart disease (CHD) in Indian population, we conducted a case-control study to assess the association of Lipoprotein (a)(Lp(a)) with CHD. One hundred and fifty one consecutive patients with clinical and angiographic evidence of CHD and forty-nine healthy controls were drawn for the study. Triglycerides, very low density cholesterol (VLDL-C), total cholesterol (total-C)/high density cholesterol (HDL-C) ratio, low density cholesterol (LDL-C)/HDL cholesterol ratio and Lp(a) were found to be higher in patients than controls. In female sex and in those with family history of CHD, higher total and LDL cholesterol levels were observed to be associated with higher Lp(a) levels. Lp(a) levels were also found to be higher in triple vessel disease than other vessel disease patients. Significant difference in Lp(a) levels were observed between normal coronaries vs. single and triple vessel disease(P<0.05) and also between single vs. double and triple vessel disease (P<0.01).Lp(a) levels correlated positively with vessel severity(P<0.005). Lp(a) levels >25 mg/dl were associated with coronary heart disease (Odds ratio 1.98 P<0.05 95% CI 0.007-1.18). Our findings suggest a cut-off level of 25mg/dl for determination of risk of CHD. Studies from different areas involving larger sample size are needed to confirm the findings of the present study.

Novel cardiac-specific biomarkers and the cardiovascular continuum

The concept of the cardiovascular continuum, introduced during the early 1990s, created a holistic view of the chain of events connecting cardiovascular-related risk factors with the progressive development of pathological-related tissue remodelling and ultimately, heart failure and death. Understanding of the tissue-specific changes, and new technologies developed over the last 25-30 years, enabled tissue remodelling events to be monitored in vivo and cardiovascular disease to be diagnosed more reliably than before. The tangible product of this evolution was the introduction of a number of biochemical markers such as troponin I and T, which are now commonly used in clinics to measure myocardial damage. However, biomarkers that can detect specific earlier stages of the cardiovascular continuum have yet to be generated and utilised. The majority of the existing markers are useful only in the end stages of the disease where few successful intervention options exist. Since a large number of patients experience a transient underlying developing pathology long before the signs or symptoms of cardiovascular disease become apparent, the requirement for new markers that can describe the early tissue-specific, matrix remodelling process which ultimately leads to disease is evident. This review highlights the importance of relating cardiac biochemical markers with specific time points along the cardiovascular continuum, especially during the early transient phase of pathology progression where none of the existing markers aid diagnosis.

Epidemiology and risk factors of cerebral ischemia and ischemic heart diseases: similarities and differences

Cerebral ischemia and ischemic heart diseases, common entities nowadays, are the main manifestation of circulatory diseases. Cardiovascular diseases, followed by stroke, represent the leading cause of mortality worldwide. Both entities share risk factors, pathophisiology and etiologic aspects by means of a main common mechanism, atherosclerosis. However, each entity has its own particularities. Ischemic stroke shows a variety of pathogenic mechanisms not present in ischemic heart disease. An ischemic stroke increases the risk of suffering a coronary heart disease, and viceversa. The aim of this chapter is to review data on epidemiology, pathophisiology and risk factors for both entities, considering the differences and similarities that could be found in between them. We discuss traditional risk factors, obtained from epidemiological data, and also some novel ones, such as hyperhomocisteinemia or sleep apnea. We separate risk factors, as clasically, in two groups: nonmodifiables, which includes age, sex, or ethnicity, and modifiables, including hypertension, dyslipidemia or diabetis, in order to discuss the role of each factor in both ischemic events, ischemic stroke and coronary heart disease.

Increased stroke risk and lipoprotein(a) in a multiethnic community: the Northern Manhattan Stroke Study

CONTEXT

Elevated lipoprotein(a) [Lp(a)] is associated with ischemic stroke (IS) among Whites, but data is sparse for non-White populations.

OBJECTIVE

Using a population-based case-control study design with subjects from the Northern Manhattan Stroke Study, we assessed whether Lp(a) levels were independently associated with IS risk among Whites, Blacks and Hispanics.

DESIGN AND SETTING

Lp(a) levels were measured in 317 IS cases (mean age 69 +/- 13 years; 56% women; 16% Whites, 31% Blacks and 52% Hispanics) and 413 community-based controls, matched by age, race/ethnicity and gender. In-person assessments included demographics, socioeconomic status, presence of vascular risk factors and fasting lipid levels. Logistic regression was used to determine the independent association of Lp(a) and IS. Stratified analyses investigated gender and race/ethnic differences.

RESULTS

Mean Lp(a) levels were greater among cases than controls (46.3 +/- 41.0 vs. 38.9 +/- 38.2 mg/dl; p < 0.01). After adjusting for stroke risk factors (hypertension, diabetes mellitus, coronary artery disease, cigarette smoking), lipid levels, and socioeconomic status, Lp(a) levels > or =30 mg/dl were independently associated with an increased stroke risk in the overall cohort (adjusted odds ratio, OR, 1.8, 95% confidence interval, CI, 1.20-2.6; p = 0.004). There was a significant linear dose-response relationship between Lp(a) levels and IS risk. The association between IS risk and Lp(a) > or =30 mg/dl was more pronounced among men (adjusted OR 2.0, 95% CI 1.1-3.5; p = 0.02) and among Blacks (adjusted OR 2.7, 95% CI 1.2-6.2; p = 0.02).

CONCLUSION

Elevated Lp(a) levels were significantly and independently associated with increased stroke risk, suggesting that Lp(a) is a risk factor for IS across White, Black and Hispanic race/ethnic groups.

Lipids and carotid plaque in the Northern Manhattan Study (NOMAS)

Background

Lipids, particularly low-density (LDL) and high-density (HDL) lipoproteins, are associated with increased risk of stroke and cardiovascular disease, probably due to atherosclerosis. The objective of this cross-sectional analysis was to investigate the relation between blood lipids and carotid plaque.

Methods

As part of a prospective population-based study to determine the incidence and risk factors of stroke in a multiethnic population, we evaluated 1804 participants with lipid measurements and B-mode ultrasound of carotid arteries (mean age 69 +/- 10 years; 40% men; 51% Hispanic, 26% black, 23% white). The association between lipid parameters and carotid plaque was analyzed by multiple logistic regression.

Results

Plaque was present in 61% of participants. Mean total cholesterol was 202 +/- 41 mg/dl. After controlling for other lipid parameters, demographics, and risk factors, the only cholesterol subfraction associated with carotid plaque was LDL (OR per standard deviation (SD) = 1.14, 95% CI 1.02-1.27). Neither HDL nor triglycerides independently predicted carotid plaque. Apolipoprotein B (ApoB) was also associated with risk of plaque (OR per SD = 1.29, 95% CI 1.03-1.60). Apolipoprotein A-I (apoA-1) was associated with a decrease in multiple plaques (OR per SD = 0.76, 95% CI 0.60-0.97), while lipoprotein a was associated with an increased risk of multiple plaques (OR per SD = 1.31, 95% CI 1.03-1.66). ApoB:ApoA-I had the strongest relation with carotid plaque (OR per SD = 1.35, 95% CI 1.08-1.69).

Conclusions

Among the common lipid parameters, LDL has the strongest relation with carotid plaque. Other lipid precursor proteins such as ApoB and ApoA-I may be stronger predictors of subclinical atherosclerosis, however, and better targets for treatment to reduce plaque formation and risk of cerebrovascular disease.

Plasma levels of lipoprotein (a) in patients with major depressive disorders

Depression and cardiovascular disease are among the most prevalent health problems. The evidence that depression is a risk factor for the development and progression of coronary heart disease has strengthened over the past several years, but the exact reasons are not yet clear. Elevated lipoprotein (a) (Lp(a)) concentrations seem to be the major factor for the progression of the atherosclerosis and coronary heart disease. In this study, we measured the plasma levels of Lp(a) in 35 patients with major depressive disorder and 35 healthy controls. The two groups were matched by age and gender. Lp(a) measurement was performed using an immunoturbidimetric method. Total cholesterol was significantly lower in the patient group (mean +/-SD: 144.65+/-22.13 vs. 186.14+/-34.48 mg/dl. The Lp(a) levels of the patient group differed significantly from control values. Patients with major depressive disorder had higher plasma levels of Lp(a) than healthy controls (34.94+/-18.01 vs. 20.08+/-11.27 mg/dl). The results of the present study suggest that the increase of Lp(a) may contribute to higher cardiovascular risk in patients with major depressive disorder.

Epidemiology of ischemic and hemorrhagic stroke: incidence, prevalence, mortality, and risk factors

The epidemiology of ischemic and hemorrhagic stroke is an ongoing exploration to identify risk factors that continue to expand with the advent of technological advancements and preventative medical practices. Identification of risk factors that can or cannot be modified is a crucial step in determining stroke risk. Many of the modifiable risk factors are well established, and specific interventions to reduce stroke risk have been established. Some risk factors are less established, and intervention to reduce risk is yet to be determined by evidence-based medicine. Data from ongoing randomized clinical trials continue to enhance our ability to prevent a first stroke.

Cardiovascular biomarkers: increasing impact of laboratory medicine in cardiology practice

The practice of cardiology is in continual evolution, in parallel with the progress achieved by medical research in understanding the pathophysiology of cardiovascular disease and in developing new therapeutic procedures. Consequently, manufacturers of cardiac biomarkers are pressed with new demands to improve the performance of the existing and the development of novel ones. Several highly sensitive and/or specific assays for myocardial ischemic damage and myocardial function detection have already become commercially available. Moreover, an increasing number of novel risk factors have been added to the classical risk factors of cardiovascular disease. Finally, the recent surge of genetic analysis procedures will likely soon provide the clinical cardiologist with a number of laboratory tests for defining the molecular diagnosis, assessing new risk factors, and better targeting the pharmaceutical approaches in patients with cardiovascular disease. In this review, we first present the general characteristics of a biomarker followed by the analytical and clinical performance of assay methods.

Changes in blood lipid levels following silastic ring vertical gastroplasty

BACKGROUND

The purpose of this study was to evaluate the effect of the Silastic Ring Vertical Gastroplasty (SRVG) operation on blood lipid levels in obese men and women during the first year following surgery.

METHODS

25 patients (11 men and 14 women) age 17-50 (mean 33 years) who suffered from morbid obesity (BMI >40, range 45.9+/-4.7 kg/m2) underwent SRVG. Blood samples were collected before operation and 3, 6 and 12 months following surgery and tested for: triglycerides, total cholesterol, HDL-C, LDL-C, VLDL-C, and Lp(a).

RESULTS

Both men and women lost weight significantly. Mean BMI decreased from 48.0 to 32.5 kg/m2 in men and from 44.3 to 29.0 kg/m2 in women (P<0.01). Blood lipid levels 1 year following surgery demonstrated the following changes: In women, triglycerides, total cholesterol, LDL, VLDL cholesterol and Lp(a) decreased from 160.7 mg/dL to 67.7 mg/dL (P<0.01), from 220 mg/dL to 189 mg/dL, from 138.3 mg/dL to 111 mg/dL, from 17 mg/dL to 12 mg/dL, and from 77.5 mg/dL to 18.5 mg/dL (P<0.01), respectively, and HDL increased from 45 mg/dL to 50.5 mg/dL. In men, triglycerides, total cholesterol, LDL, VLDL cholesterol and Lp(a) decreased from 246 mg/dL to 140 mg/dL (P<0.01), from 206 mg/dL to 170 mg/dL (P<0.01), from 134 mg/dL to 112 mg/dL (P<0.05), from 25 mg/dL to 15 mg/dL (P<0.01), and from 30.3 mg/dL to 11.6 mg/dL (P<0.01), respectively, and HDL increased from 31.3 mg/dL to 37.4 mg/dL (P<0.05).

CONCLUSION

SRVG improved blood lipid profile in obese patients during the first year following surgery. Reduction in cholesterol and its fractions reaches statistical significance only in men.

Convergence of genes implicated in Alzheimer's disease on the cerebral cholesterol shuttle: APP, cholesterol, lipoproteins, and atherosclerosis

Polymorphic genes associated with Alzheimer's disease (see ) delineate a clearly defined pathway related to cerebral and peripheral cholesterol and lipoprotein homoeostasis. They include all of the key components of a glia/neurone cholesterol shuttle including cholesterol binding lipoproteins APOA1, APOA4, APOC1, APOC2, APOC3, APOD, APOE and LPA, cholesterol transporters ABCA1, ABCA2, lipoprotein receptors LDLR, LRP1, LRP8 and VLDLR, and the cholesterol metabolising enzymes CYP46A1 and CH25H, whose oxysterol products activate the liver X receptor NR1H2 and are metabolised to esters by SOAT1. LIPA metabolises cholesterol esters, which are transported by the cholesteryl ester transport protein CETP. The transcription factor SREBF1 controls the expression of most enzymes of cholesterol synthesis. APP is involved in this shuttle as it metabolises cholesterol to 7-betahydroxycholesterol, a substrate of SOAT1 and HSD11B1, binds to APOE and is tethered to LRP1 via APPB1, APBB2 and APBB3 at the cytoplasmic domain and via LRPAP1 at the extracellular domain. APP cleavage products are also able to prevent cholesterol binding to APOE. BACE cleaves both APP and LRP1. Gamma-secretase (PSEN1, PSEN2, NCSTN) cleaves LRP1 and LRP8 as well as APP and their degradation products control transcription factor TFCP2, which regulates thymidylate synthase (TS) and GSK3B expression. GSK3B is known to phosphorylate the microtubule protein tau (MAPT). Dysfunction of this cascade, carved out by genes implicated in Alzheimer's disease, may play a major role in its pathology. Many other genes associated with Alzheimer's disease affect cholesterol or lipoprotein function and/or have also been implicated in atherosclerosis, a feature of Alzheimer's disease, and this duality may well explain the close links between vascular and cerebral pathology in Alzheimer's disease. The definition of many of these genes as risk factors is highly contested. However, when polymorphic susceptibility genes belong to the same signaling pathway, the risk associated with multigenic disease is better related to the integrated effects of multiple polymorphisms of genes within the same pathway than to variants in any single gene [Wu, X., Gu, J., Grossman, H.B., Amos, C.I., Etzel, C., Huang, M., Zhang, Q., Millikan, R.E., Lerner, S., Dinney, C.P., Spitz, M.R., 2006. Bladder cancer predisposition: a multigenic approach to DNA-repair and cell-cycle-control genes. Am. J. Hum. Genet. 78, 464-479.]. Thus, the fact that Alzheimer's disease susceptibility genes converge on a clearly defined signaling network has important implications for genetic association studies.

Primary Prevention of Ischemic Stroke

Background and Purpose— This guideline provides an overview of the evidence on various established and potential stroke risk factors and provides recommendations for the reduction of stroke risk.

Methods— Writing group members were nominated by the committee chair on the basis of each writer’s previous work in relevant topic areas and were approved by the American Heart Association Stroke Council’s Scientific Statement Oversight Committee. The writers used systematic literature reviews (covering the time period since the last review published in 2001 up to January 2005), reference to previously published guidelines, personal files, and expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulate recommendations based on standard American Heart Association criteria. All members of the writing group had numerous opportunities to comment in writing on the recommendations and approved the final version of this document. The guideline underwent extensive peer review before consideration and approval by the AHA Science Advisory and Coordinating Committee.

Results— Schemes for assessing a person’s risk of a first stroke were evaluated. Risk factors or risk markers for a first stroke were classified according to their potential for modification (nonmodifiable, modifiable, or potentially modifiable) and strength of evidence (well documented or less well documented). Nonmodifiable risk factors include age, sex, low birth weight, race/ethnicity, and genetic factors. Well-documented and modifiable risk factors include hypertension, exposure to cigarette smoke, diabetes, atrial fibrillation and certain other cardiac conditions, dyslipidemia, carotid artery stenosis, sickle cell disease, postmenopausal hormone therapy, poor diet, physical inactivity, and obesity and body fat distribution. Less well-documented or potentially modifiable risk factors include the metabolic syndrome, alcohol abuse, drug abuse, oral contraceptive use, sleep-disordered breathing, migraine headache, hyperhomocysteinemia, elevated lipoprotein(a), elevated lipoprotein-associated phospholipase, hypercoagulability, inflammation, and infection. Data on the use of aspirin for primary stroke prevention are reviewed.

Conclusion— Extensive evidence is available identifying a variety of specific factors that increase the risk of a first stroke and providing strategies for reducing that risk.

Plasma lipoprotein(a) levels: a comparison between diabetic and non-diabetic patients with acute ischemic stroke

OBJECTIVE: The aim of this study was to evaluate lipoprotein(a) (Lp(a)), total cholesterol, high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL), very low density lipoprotein cholesterol (VLDL ), triglycerides , apolipoprotein A (apo A) and B100 (apo B100), uric acid, glycaemic and insulin plasmatic concentrations in patients affected by acute stroke. In this group of patients, we have compared the variables between type 2 diabetic patients and non-diabetic patients. METHOD: We evaluate a total of 34 non-diabetic patients (22 males and 12 females; mean age 66.71 ± 10.83 years) and a group of 26 type 2 diabetic patients (15 males and 11 females; mean age 66.35 ± 9.92 years) in a cross-sectional study. RESULTS: Mean Lp(a) concentration did not significantly differ between type 2 diabetic patients and non-diabetic subjects (29.49 ± 23.09 vs 44.81 ± 44.34 mg/dl). The distribution of Lp(a)levels was highly skewed towards the higher levels in both groups, being over 30 mg/dl in 50%. Lp(a) concentration was positively correlated with abdominal adiposity, using waist-hip ratio(WHR)(p< 0.05). No association was found between Lp(a) and others risk factors like sex, age, other lipidic parameters and the presence of stroke. CONCLUSIONS: Our results showed that there were no significant differences between diabetic and non-diabetic patients' serum Lp(a) levels, which indicates that elevated Lp(a) levels were associated with ischemic stroke, irrespective of the presence of type 2 diabetes mellitus (type 2 DM).

Does Lipoprotein(a) Inhibit Elastolysis in Abdominal Aortic Aneurysms?

PURPOSE

to test the hypothesis that there is a negative association between serum levels of lipoprotein(a) (Lp(a)) and elastin-derived peptides (EDP) as well as matrix metalloproteinase (MMP)-9 activation in the aneurysm wall in patients with asymptomatic abdominal aortic aneurysms (AAA).

MATERIAL AND METHODS

from 30 patients operated for asymptomatic AAAs, preoperative serum samples and AAA biopsies were collected. Lp(a) (mg/L) and EDP (ng/ml) in serum were measured by enzyme linked immunosorbent assays. MMP-9 activity (arbitrary units) in the AAA wall was measured by gelatin zymography and the ratio: active MMP-9/total MMP-9 were calculated.

RESULTS

there was a significant negative correlation (Spearman's rho) between serum levels of Lp(a) and EDP (r= -0.707, p<0.001), as well as the share of activated MMP-9 (r= -0.461, p=0.01) in the AAA wall.

CONCLUSION

this preliminary study indicate that Lp(a) inhibit elastolysis in asymptomatic AAA.

The increasing impact of laboratory medicine on clinical cardiology

The practice of cardiology continues to evolve along with a better understanding of the pathophysiology of cardiovascular disease and the development of new therapeutic procedures. Consequently, new demands are being made on the in vitro diagnostics industry to improve the performance of existing cardiac markers and to develop novel markers for new cardiac disease indications. Indeed, in the last 20 years there has been a progressive increase in new laboratory tests for markers of cardiac diseases. Several highly sensitive and/or specific assays for the detection of myocardial ischemic damage as well as some immunoassays for cardiac natriuretic hormones, now considered a reliable marker of myocardial function, have become commercially available. In parallel, a growing number of some novel risk factors, which can be assessed and monitored by laboratory methods, have been added to the classical risk factors for cardiovascular disease. Finally, the recent explosion of genetic analysis may soon place at the clinical cardiologist's disposal many laboratory tests for defining the diagnosis at the molecular level, assessing new risk factors, and better targeting the pharmaceutical approaches in patients with cardiovascular disease. In the present article, after a brief description of the analytical tests included in these four groups, each group's impact on clinical cardiology is discussed in detail.

Relationship of lipoprotein(a) with intimal medial thickness of the carotid artery in Type 2 diabetic patients in south India

OBJECTIVE

The objective of this study was to investigate the association of lipoprotein(a) [Lp(a)] levels with intimal medial thickness (IMT) in Type 2 diabetic patients in south India.

STUDY DESIGN

We studied 587 consecutive Type 2 diabetic patients at the M.V. Diabetes Specialities Centre, Chennai. The mean age of the study group was 55 +/- 10 years and 71.2% were males. IMT of the right common carotid artery was determined using high-resolution B mode ultrasonography. Lp(a) levels were measured using ELISA. Since the frequency distribution of Lp(a) was skewed, Lp(a) values were log transformed and the geometric mean was used for statistical analysis. The tertiles of IMT were determined to analyse the association of Lp(a) and other factors with IMT.

RESULT

The mean Lp(a) level in the study patients was 18.9 +/- 3.1 mg/dl (geometric mean +/- sd) and the mean IMT of the study subjects was 0.93 +/- 0.19 mm (mean +/- sd). The prevalence of carotid atherosclerosis (defined as IMT > 1.1 mm) among subjects with elevated Lp(a) levels > 20 mg/dl was significantly higher compared with those with Lp(a) levels </= 20 mg/dl (26.9% vs. 16.3%, P = 0.003). Lp(a) levels increased with increase in tertiles of IMT (anova, P < 0.05). Pearson correlation analysis of carotid IMT with other cardiovascular risk factors revealed strong correlation of IMT with age (P < 0.0001), duration of diabetes (P < 0.0001), systolic blood pressure (P < 0.0001), diastolic blood pressure (P = 0.006), LDL-cholesterol (P = 0.023), HbA1c (P = 0.017) and Lp(a) (P < 0.0001). Multiple logistic regression analysis showed age (P = 0.010), LDL-cholesterol (P = 0.032) and Lp(a) (P = 0.021) to be associated with carotid atherosclerosis.

CONCLUSION

The results suggest that Lp(a) has a strong association with IMT of carotid arteries in Type 2 diabetic subjects in south India.

APO(a) variants and lipoprotein(a) in men with or without myocardial infarction

The lipoprotein Lp(a) with high plasma concentration is an independent genetic determinant for cardiovascular diseases. It was investigated as a quantitative factor of risk for myocardial infarction. A total of 345 Italian subjects, 127 Cases and 218 Controls, were studied. Lipids and lipoproteins were compared. Cases had atherogenic traits, such as lower HDL cholesterol and higher triglycerides than Controls. In particular, they had Lp(a) concentrations over the risk threshold, (median, 27 mg/dl in Cases vs 17 mg/dl in Controls; P = 0.0075, Mann-Whitney test) which confirmed the association of this parameter with the disease. Two main functional variants of the apo(a) gene, KringleIV and penta-nucleotide repeat, (PNR) were analyzed. Allele and genotype frequency distributions differed between Cases and Controls. Lp(a) concentrations differed according to PNR genotypes in Controls: subjects having alleles >8 showed lower Lp(a). This was not found in Cases. They had a higher prevalence of the smaller KringleIV alleles, the high Lp(a)-expressing ones. In Cases, genotypes consisting of two small KringleIV alleles were prevalently associated to PNR 8/9 and 8/10, thus preventing Lp(a) lowering. The putative apo(a) enhancer within LINE1 in the apo(a)-plasminogen intergenic region was investigated for functional polymorphisms. No variants that could be associated to the Lp(a) variability were found.

The role of risk factors in the development of atherosclerosis

Our understanding of risk factors for atherogenesis has changed significantly over the last decade. In addition to better grasp of the mechanism of action of the "classic" (causal) risk factors, a number of potentially important new factors has emerged. In this review we briefly summarize the evidence of the relation between atherosclerosis and the currently recognized causal risk factors, namely, age, smoking, LDL cholesterol, HDL cholesterol, hypertension, and diabetes. More emphasis has been put on description of the emerging entities such as atherogenic profile of plasma lipoproteins with discussion of LDL and HDL subclasses, Lp(a), homocysteine, and, last but not least, on the role of infection and inflammation in atherogenesis. Whenever possible, we tried to summarize the relevant lines of evidence such as epidemiological, pathological, genetic, and clinical trial data linking the specific factor with atherosclerosis.