Femoral Plaques Confound the Association of Circulating Oxidized Low-Density Lipoprotein With Carotid Atherosclerosis in a General Population Aged 35 to 55 Years

The Interplay of Vitamin D Deficiency and Cellular Senescence in The Pathogenesis of Obesity-Related Co-Morbidities

This scoping review aims to clarify the interplay between obesity, vitamin D deficiency, cellular senescence, and obesity-related metabolic consequences, mainly subclinical atherosclerosis, and non-alcoholic fatty liver disease (NAFLD). Obesity is a significant global health problem that involves cellular, environmental, behavioral, and genetic elements. The fundamental cause of obesity throughout all life stages is an energy imbalance, and its consequences are countless and, foremost, very common. Obesity has been comprehensively studied in the literature given its association with low serum vitamin D, with many proposed mechanisms linking the two conditions. Moreover, markers of exaggerated cellular senescence have been proven to accumulate in obese individuals. Subclinical atherosclerosis initiates an early stage that ends in serious cardiac events, and obesity, low vitamin D, and senescent cells largely contribute to its associated chronic low-grade inflammation. Furthermore, NAFLD signifies the hepatic manifestation of metabolic syndrome, and studies have highlighted the important role of obesity, vitamin D deficiency, and cellular senescence in its development. Therefore, we outlined the most important mechanisms tying these conditions to one another.

Relationship between lipoproteins, thrombosis and atrial fibrillation

The prothrombotic state in atrial fibrillation (AF) occurs as a result of multifaceted interactions, known as Virchow’s triad of hypercoagulability, structural abnormalities, and blood stasis. More recently, there is emerging evidence that lipoproteins are implicated in this process, beyond their traditional role in atherosclerosis. In this review, we provide an overview of the various lipoproteins and explore the association between lipoproteins and AF, the effects of lipoproteins on haemostasis, and the potential contribution of lipoproteins to thrombogenesis in AF. There are several types of lipoproteins based on size, lipid composition, and apolipoprotein category, namely: chylomicrons, very low-density lipoprotein, low-density lipoprotein (LDL), intermediate-density lipoprotein, and high-density lipoprotein. Each of these lipoproteins may contain numerous lipid species and proteins with a variety of different functions. Furthermore, the lipoprotein particles may be oxidized causing an alteration in their structure and content. Of note, there is a paradoxical inverse relationship between total cholesterol and LDL cholesterol (LDL-C) levels, and incident AF. The mechanism by which this occurs may be related to the stabilizing effect of cholesterol on myocardial membranes, along with its role in inflammation. Overall, specific lipoproteins may interact with haemostatic pathways to promote excess platelet activation and thrombin generation, as well as inhibiting fibrinolysis. In this regard, LDL-C has been shown to be an independent risk factor for thromboembolic events in AF. The complex relationship between lipoproteins, thrombosis and AF warrants further research with an aim to improve our knowledge base and contribute to our overall understanding of lipoprotein-mediated thrombosis.

Association of Plasma Marker of Oxidized Lipid with Histologic Plaque Instability in Patients with Peripheral Artery Disease

BACKGROUND

The association between oxidized low-density lipoprotein (OxLDL) and plaque instability in coronary and carotid artery disease is well established. However, the association between OxLDL and the histologic changes of plaque in peripheral artery disease has not been clearly elucidated. This study aims to investigate the association between plasma OxLDL and histologic plaque instability in patients with peripheral artery disease.

METHODS

Prospectively obtained plaques from 48 patients who underwent endovascular atherectomy (n = 20), surgical endarterectomy (n = 9), or bypass surgery (n = 19) for treatment of atherosclerotic femoropopliteal artery disease were evaluated for histologic fibrosis, sclerosis, calcification, necrosis, cholesterol cleft, and foamy macrophages using hematoxylin and eosin, oil red O, and immunohistochemical staining. Unstable plaques were defined as plaques that were positive for foamy macrophages and with lipid content of more than 10% of the total plaque area. Plasma OxLDL levels were measured using an enzyme-linked immunosorbent assay (Mercodia AB, Uppsala, Sweden).

RESULTS

Of the 48 patients, 26 (54%) had unstable plaques. The unstable plaque group was younger, had fewer angiographic total occlusions, less calcification, and more CD68-positive and LOX-1-positive cells than the stable plaque group. Plasma OxLDL levels were significantly higher in the unstable plaque group than in the stable plaque group (57.4 ± 13.9 vs. 47.2 ± 13.6 U/L, P = 0.014). Multivariate analysis revealed that plasma OxLDL level, smoking, angiographic nontotal occlusion, and statin nonuse were independent predictors of unstable plaque.

CONCLUSIONS

Among patients with peripheral artery disease, the histologic instability of femoropopliteal plaque was independently associated with high plasma OxLDL, smoking, nontotal occlusion, and statin nonuse. Further large-scale studies are necessary to evaluate the role of noninvasive OxLDL measurement for predicting plaque instability and future adverse vascular event.

Comparative effects of high-dose atorvastatin versus rosuvastatin on lipid parameters, oxidized low-density lipoprotein, and proprotein convertase subtilisin kexin 9 in acute coronary syndrome

AIM

Current guidelines recommend administration of high-dose statins in acute coronary syndrome (ACS). It has been reported that statins upregulate proprotein convertase subtilisin kexin 9 (PCSK9) mRNA expression and increase circulating PCSK9 levels. We aimed to compare the effects of high-dose atorvastatin and rosuvastatin on serum oxidized low-density lipoprotein (oxidized-LDL) and PCSK9 levels in statin-naive patients with ACS.

PATIENTS AND METHODS

One hundred and six patients with ACS were enrolled in this study. The patients were assigned randomly to receive atorvastatin (80 mg/day) or rosuvastatin (40 mg/day) by using a ratio of 1 : 1 in randomization. The levels of total cholesterol (TC), triglyceride, high-density lipoprotein cholesterol, LDL-cholesterol, oxidized-LDL, and PCSK9 were compared between groups after a 4-week treatment.

RESULTS

Our study population included 53 patients in the atorvastatin group (age: 58.13±11.30 years, 11.32% female) and 53 patients in the rosuvastatin group (age: 59.08±12.44 years, 15.09% female). In both groups, lipid parameters, oxidized-LDL, and PCSK9 values changed significantly according to the baseline following treatment. High-dose atorvastatin and rosuvastatin induced similar decreases in LDL-cholesterol, oxidized-LDL, and triglyceride levels and similarly increased in high-density lipoprotein cholesterol and PCSK9 levels (P>0.05).

CONCLUSION

We showed that atorvastatin and rosuvastatin treatment regimens have comparable effects on lipid parameters and PCSK9 levels in ACS patients.

DUSP1 Is a Potential Marker of Chronic Inflammation in Arabs with Cardiovascular Diseases

Background

Cardiovascular disease (CVD) risks persist in patients despite the use of conventional treatments. This might be due to chronic inflammation as reflected in epidemiological studies associating circulating low-grade inflammatory markers with CVD recurrent events. Here, we explored this potential link by assessing plasma dual-specificity phosphatase 1 (DUSP1) levels and comparing them to high-sensitivity CRP (hsCRP) and oxidized low-density lipoprotein (oxLDL) levels and their associations to conventional CVD risk factors in confirmed CVD patients.

Methods

Human adults with reported CVD (n = 207) and controls (n = 70) living in Kuwait were used in this study. Anthropometric and classical biochemical parameters were determined. Plasma levels of DUSP1, oxLDL, and hsCRP were measured using human enzyme-linked immunosorbent assay kits.

Results

DUSP1 and hsCRP plasma levels and their least square means were higher in CVD cases, while oxLDL plasma levels were lower (p < 0.05). Multivariate logistic regression analysis showed that DUSP1 and hsCRP are independently associated with CVD in the studied population, as reflected by 2-fold and 1.5-fold increased risks with increased levels of DUSP1 and hsCRP, respectively. In our study, DUSP1 levels were found to be associated with CVD despite statin treatment and diabetes status (p < 0.05), whereas hsCRP mainly correlated with obesity markers.

Conclusions

Circulating DUSP1 might be a predictor of chronic subclinical inflammation and residual risk in CVD patients, whereas our data suggest that the association between hsCRP and CVD is largely accounted for adiposity risk factors.

Leukocyte telomere length and diet in the apparently healthy, middle-aged Asklepios population

Telomere length is a prognostic biomarker for aging diseases. As it is unknown whether diet plays a role in these associations, we aimed to assess the impact of diet on telomere length. Moreover, given that telomere length is modulated by oxidative stress and inflammation, an additional goal was to evaluate whether the latter may mediate possible telomere - diet associations. Southern blot measured leukocyte telomere length and food frequency questionnaire data were compared for 2509 apparently healthy men and women (~35 to 55 years) from the Asklepios population. No significant associations were found between telomere length and overall dietary characteristics, such as dietary diversity, quality, equilibrium, and the dietary inflammatory index. Exploratory analysis of individual dietary variables revealed that a higher daily intake of deep fried potato products was associated with shorter telomeres (P = 0.002, 151 bp per 100 g/day), also in both sexes separately. Deep fried potato product consumption was also significantly associated with C-reactive protein (P = 0.032) and uric acid (P = 0.042), but not other inflammation and oxidative stress markers. These results suggest an at most limited association between overall dietary patterns and telomere length in the general population. Nevertheless, the association between telomere length and deep fried potato product intake warrants additional research.

Femoral Artery Ultrasound Examination

We compared intima–media thickness (IMT) and the prevalence of plaques in the common carotid artery (CCA) and common femoral artery (CFA) in apparently healthy participants. This multicenter study included 322 participants (59.9% female; age 20-78 years, mean 52.1 ± 15.3 years) who underwent Echo-color Doppler examination of the CCA and CFA bilaterally. Prevalence and composition of plaque were recorded. A significant ( P < .01) difference between mean CCA-IMT and mean CFA-IMT was detected (0.70 vs 0.73 mm). Plaque prevalence was significantly higher in the CFA compared to the CCA (40.7% vs 30.4%). Atherosclerotic plaques were found in both CFA and CCA in 46% of the cases, solely in CFA in 38%, and in CCA alone in 17%. The observed difference in plaque prevalence was even greater when only fibrolipid isolated plaques were considered (CFA 39.4% vs CCA 22.1%). In a healthy general population, atherosclerotic plaques were present in the CFA but not in the CCA in over one-third of the cases. Further studies must confirm whether ultrasonography of the CFA might be introduced in the screening protocols for cardiovascular risk assessment.

The Ten-Year History of the Asklepios Study: An Interview with Professor Ernst R. Rietzschel, Primary Investigator and Leader of the Asklepios Study

The Asklepios study started 10 years ago when 2,500 subjects were screened between 2002 and 2004. And all of the 90+ publications we have for the moment are from those cross-sectional data. This is called round 1. Since 2011, in round 2, all of those patients have started to come back for a 10-year follow-up. At this moment, approximately 1,750 of those patients have been seen. The patients were followed by general practitioners (GP), and the GP again provided the information about what has happened with the medical status in the past 10 years including drug therapy: not only the drugs that they are taking at the moment were evaluated, but, because patients often use many drugs, the chronicles of drugs for major risk factors, for hypertension, lipids, contraceptives and more. Then, patients come to the study center where the same cluster of examinations are undertaken by one single doctor, Prof. Ernst R. Rietzschel and one study nurse, just like 10 years ago. Again, using a single observer at the two time frames has kept the methodology very strict.

The Additive Value of Femoral Ultrasound for Subclinical Atherosclerosis Assessment in a Single Center Cohort of 962 Adults, Including High Risk Patients with Rheumatoid Arthritis, Human Immunodeficiency Virus Infection and Type 2 Diabetes Mellitus

BACKGROUND

Presence of femoral atheromatic plaques, an emerging cardiovascular disease (CVD) biomarker additional to carotid plaques, is poorly investigated in conditions associating with accelerated atherosclerosis such as Rheumatoid Arthritis (RA), Human Immunodeficiency Virus (HIV) infection and Type 2 Diabetes Mellitus (T2DM).

OBJECTIVE/METHODS

To assess the frequency of femoral/carotid subclinical atheromatosis phenotypes in RA, HIV and T2DM and search for each disease-specific probability of either femoral and/or carotid subclinical atheromatosis, we examined by ultrasound a single-center cohort of CVD-free individuals comprised of consecutive non-diabetic patients with RA (n=226) and HIV (n=133), T2DM patients (n=109) and non-diabetic individuals with suspected/known hypertension (n=494) who served as reference group.

RESULTS

Subclinical atheromatosis--defined as local plaque presence in at least on arterial bed--was diagnosed in 50% of the overall population. Among them, femoral plaques only were found in 25% of either RA or HIV patients, as well as in 16% of T2DM patients and 35% of reference subjects. After adjusting for all classical CVD risk factors, RA and HIV patients had comparable probability to reference group of having femoral plaques, but higher probability (1.75; 1.17-2.63 (odds ratio; 95% confidence intervals), 2.04; 1.14-3.64, respectively) of having carotid plaques, whereas T2DM patients had higher probability to have femoral and carotid plaques, albeit, due to their pronounced dyslipidemic profile.

CONCLUSION

RA and HIV accelerate predominantly carotid than femoral. A "two windows" carotid/femoral, rather than carotid alone ultrasound, screening improves substantially subclinical atheromatosis detection in patients at high CVD risk.

Relationship of lipid oxidation with subclinical atherosclerosis and 10-year coronary events in general population

OBJECTIVES

To assess 1) the association of lipid oxidation biomarkers with 10-year coronary artery disease (CAD) events and subclinical atherosclerosis, and 2) the reclassification capacity of these biomarkers over Framingham-derived CAD risk functions, in a general population.

METHODS

Within the framework of the REGICOR study, 4782 individuals aged between 25 and 74 years were recruited in a population-based cohort study. Follow-up of the 4042 who met the eligibility criteria was carried out. Plasma, circulating oxidized low-density lipoprotein (oxLDL) and oxLDL antibodies (OLAB) were measured in a random sample of 2793 participants. End-points included fatal and non-fatal acute myocardial infarction (AMI) and angina. Carotid intima-media thickness (IMT) in the highest quintile and ankle-brachial index <0.9 were considered indicators of subclinical atherosclerosis.

RESULTS

Mean age was 50.0 (13.4) years, and 52.4% were women. There were 103 CAD events (34 myocardial infarction, 43 angina, 26 coronary deaths), and 306 subclinical atherosclerosis cases. Oxidized LDL was independently associated with higher incidence of CAD events (HR = 1.70; 95% Confidence Interval: 1.02-2.84), but not with subclinical atherosclerosis. The net classification index of the Framingham-derived CAD risk function was significantly improved when ox-LDL was included (NRI = 14.67% [4.90; 24.45], P = 0.003). No associations were found between OLAB and clinical or subclinical events. The reference values for oxLDL and OLAB are also provided (percentiles).

CONCLUSIONS

OxLDL was independently associated with 10-year CAD events but not subclinical atherosclerosis in a general population, and improved the reclassification capacity of Framingham-derived CAD risk functions.

Addition of a novel, protective family history category allows better profiling of cardiovascular risk and atherosclerotic burden in the general population. The Asklepios Study

Objectives

Whereas the importance of family history (FH) is widely recognized in cardiovascular risk assessment, its full potential could be underutilized, when applied with its current simple guidelines-based definition (cFH): presence of premature cardiovascular disease (CVD) in a first-degree relative. We tested the added value of a new, extended family history definition (eFH), also taking into account later onset of disease, second-degree relatives and number of affected relatives, on profiling cardiovascular risk and atherosclerotic burden in the general population.

Design

longitudinal population study.

Setting

random, representative population sample from Erpe-Mere and Nieuwerkerken (Belgium, primary care).

Subjects

2524 male/female volunteers, aged 35–55 years, free from overt CVD.

Main outcome measures

Subjects were extensively phenotyped including presence of atherosclerosis (ultrasound) and a newly developed FH questionnaire (4 generations).

Results

Compared to cFH, eFH was superior in predicting an adverse risk profile (glycemic state, elevated blood pressure, lipid abnormalities, presence of metabolic syndrome components) and presence of atherosclerosis (all age & sex-adjusted p<0.05). Unlike cFH, eFH remained a significant predictor of subclinical atherosclerosis after adjusting for confounders. Most relations with eFH were not graded but showed clear informational breakpoints, with absence of CVD (including late onset) in any first-degree relative being a negative predictor of atherosclerosis, and a particularly interesting phenotype for further study.

Conclusions

A novel, extended FH definition is superior to the conventional definition in profiling cardiovascular risk and atherosclerotic burden in the general population. There remain clear opportunities to refine and increase the performance and informational content of this simple, readily-available inexpensive tool.

LDL Oxidation and Its Association With Carotid Artery Intima-Media Thickness and Other Cardiovascular Risk Factors in a Sample of Spanish General Population

We studied the association between oxidized low-density lipoproteins (OxLDLs) and early atherosclerosis, assessed by carotid artery intima-media thickness (cIMT), as well as with other known atherosclerosis risk factors in a sample of the general middle- and old-age population of Burgos (Spain). Circulating OxLDL showed a significant and independent association with the average cIMT of both carotid arteries but not with the absence or presence of ≥1 carotid atheroma plaques. Plasma OxLDL concentrations were associated with age, smoking, low-density lipoprotein-cholesterol, and triglycerides, independently of other variables. Our findings in an asymptomatic sample representative of the Spanish middle- and old-age population underscore the role of OxLDL in early atherosclerosis represented by the cIMT especially in older asymptomatic individuals, but this cannot be extended to more advanced atherosclerosis, represented by carotid plaques.

Association between presence of the metabolic syndrome and its components with carotid intima-media thickness and carotid and femoral plaque area: a population study

BACKGROUND

We aimed to explore the association between presence and number of components of the Metabolic Syndrome (MetS) and subclinical atherosclerosis outcomes (common carotid intima media thickness, plaque presence and sum of plaque area) in both the carotid and femoral bifurcations.

METHODS

Cross-sectional analysis of 771 volunteers from the ongoing epidemiological Cyprus Study (46% male; mean age = 60.1 ± 9.8). (a) Carotid intima-media thickness (IMTcc), (b) sum of plaque area in the carotid bifurcations (sum of the largest plaques in each carotid bifurcation-SPAcar), (c) sum of plaque area in the femoral bifurcations (sum of the largest plaques in each femoral bifurcation-SPAfem) and (d) sum of plaque area in both carotid and femoral bifurcations (sum of the areas of the largest plaques present in each of the four bifurcations-SPA) were measured at baseline using ultrasound. Presence and number of components of the MetS was ascertained using the National Cholesterol Education Program ATPIII definition and their association tested using multivariable regression models.

RESULTS

MetS was present in 259 (33.6%) individuals and was associated with a 0.02 mm increase in IMTcc (95% CI: 0.00 to 0.04, p = 0.047) after adjustment for age, sex, family history of CVD, alcohol consumption (BU/week) and smoking (pack-years). Each additional component of the MetS was associated with a 16% higher SPA (95% CI: 6.8% to 25.2%, pfor trend = 0.001), a 10% higher SPAcar (95% CI: 5% to 24%, pfor trend = 0.003) and a 14% higher SPAfem in the adjusted model.

CONCLUSIONS

We confirm an association between the MetS and IMTcc as well as report for the first time an association between the MetS and its components and femoral plaque area, in a general population over 40 years of age. Having any risk factors for the MetS increases the risk for subclinical atherosclerosis, with the risk increasing with each additional component. Using the dichotomous definition of the MetS may be overlooking the risk for subclinical atherosclerosis -and by inference future cardiovascular events- associated with having less than 3 risk factors.

Oral contraceptives modify DNA methylation and monocyte-derived macrophage function

Background

Fertile women may be encouraged to use contraception during clinical trials to avoid potential drug effects on fetuses. However, hormonal contraception interferes with pharmacokinetics and pharmacodynamics and modifies internal milieus. Macrophages depend on the milieu to which they are exposed. Therefore, we assessed whether macrophage function would be affected by the use of combined oral contraceptives (OCs) and if this influence depended on the androgenic or non-androgenic properties of progestin.

Methods

Healthy adult women were enrolled and stratified into two groups: women who did not use OCs (Fs) and women treated with OCs (FOCs). FOCs were further stratified as a function of androgenic (FOCA⁺) and non-androgenic (FOCA^-) properties of progestins. Routine hematological, biochemical, inflammatory and endothelial dysfunction parameters were measured. Monocyte-derived macrophages (MDMs) were evaluated for the expression and activity of estrogen receptors and androgen receptors, and release of tumor necrosis factor α (TNFα) was measured from unstimulated and lipopolysaccharide-stimulated cells.

Results

As is already known, the use of OCs changed numerous parameters: the number of lymphocytes, iron levels, total iron-binding capacity of transferrin, triglycerides, high-density lipoprotein, total cholesterol, and C-reactive protein increased, while prothrombin time and alkaline phosphatase decreased. Hormonal levels also varied: cortisol was higher in FOCs, while luteinizing hormone, follicle-stimulating hormone, and testosterone were lower in FOCs. Asymmetric dimethylarginine, an index of endothelial function, was lower in FOC than in Fs, as were cysteine and bilirubin. The androgenic properties of progestins affected the activity of OCs: in particular, white blood cell count, hemoglobin, high-density lipoprotein and calcium were higher in FOCA^- than in FOCA⁺, whereas percentage oxygen saturation and γ-glutamyl transpeptidase were lower in FOCA^- than in FOCA⁺. Importantly, FOCs had a lower global DNA methylation, indicating that OC may have epigenetic effects on gene expression. OC did not modify the expression of androgen receptor but increased estrogen receptor α expression, more considerably in FOCA⁺, and decreased estrogen receptor β, more considerably in FOCA^-. Importantly, the activation state of estrogen receptor β in FOCs was decreased, while estrogen receptor α was not active in either Fs or FOCs. Unstimulated MDMs obtained from FOCs showed higher release of TNFα in comparison with Fs. After lipopolysaccharide stimulation, the release of TNFα was significantly higher in Fs than in FOCs.

Conclusions

OC use induced many changes in hematological and plasmatic markers, modifying hormonal levels, endothelial function, inflammation index and some redox state parameters, producing a perturbation of the internal milieu that impacted macrophagic function. In fact, different levels of estrogen receptor expression and release of TNFα were observed in macrophages derived from OC users. Some of the above activities were linked to the androgenic properties of progestin. Even though it is not known whether these effects are reversible, the results indicate that to avoid potential skewing of results only a single type of OC should be used during a single clinical trial.

High density lipoprotein cholesterol level is a robust predictor of lipid peroxidation irrespective of gender, age, obesity, and inflammatory or metabolic biomarkers

BACKGROUND

Obesity related dyslipidemia, chronic inflammation and oxidative stress were associated with atherosclerotic sequels. We analysed oxidized low-density lipoprotein (oxLDL) plasma levels of 797 participants of the STyrian Juvenile OBesity (STYJOBS) / Early DEteCTion of Atherosclerosis (EDECTA) Study cohort aged from 5 to 50 years. The rationale of STYJOBS/EDECTA is to investigate the preclinical phase of obesity by a well defined cohort of young and middle aged overweight/obese and normal weight subjects.

METHODS AND RESULTS

Plasma oxLDL was analysed by ELISA (Mercodia, Sweden). In the overweight/obese (OW/OB) study group, oxLDL levels were significantly increased compared to normal weighted controls (p<0.001). Probands with metabolic syndrome (MS) had significantly higher oxLDL levels than probands without MS; between overweight and obese participants, and between females and males, no significant difference was seen. In a multiple stepwise regression analysis including all study subjects, age, gender, anthropometric data, presence of metabolic syndrome, systolic, diastolic blood pressure, carotis communis intima media thickness, lipids, adipokines, metabolic, and inflammatory biomarkers, decreased high-density lipoprotein (HDL-cholesterol) and increased total cholesterol were the best predictors for increased oxLDL levels.

CONCLUSION

Decreased HDL-cholesterol is an important determinant of lipid peroxidation irrespective of obesity, age, gender, SAT distribution, and inflammatory/metabolic biomarkers.

Oxidized low-density lipoprotein and ankle-brachial pressure index in patients with clinically evident peripheral arterial disease

OBJECTIVES

To investigate whether oxidized low-density lipoprotein is a suitable predictor of peripheral arterial disease severity. The role of oxidized low-density lipoprotein in the pathogenesis of atherosclerosis has already been investigated. Its relevance as a predictor of the appearance and worsening of coronary arterial disease is also well known. However, the same is not true regarding peripheral arterial disease.

METHOD

Eighty-five consecutive patients with an ankle-brachial pressure index (ABPI) < 0.9 and the presence of either intermittent claudication or critical lower leg ischemia were included. The plasma level of IgG autoantibodies against oxidized low-density lipoprotein was evaluated through an enzyme-linked immunosorbent assay. The results were categorized into quartiles according to the ankle-brachial pressure index (a marker of peripheral arterial disease severity), and significant differences were investigated with the Kruskal-Wallis test.

RESULTS

There was no significant difference between the quartiles for this population (p = 0.33). No correlation was found between the ankle-brachial pressure index and oxidized low-density lipoprotein levels in subjects with clinically evident peripheral arterial disease with a wide range of clinical manifestations.

CONCLUSIONS

Oxidized low-density lipoprotein is not a good predictor of peripheral arterial disease severity.

Low wall shear stress predicts subsequent development of wall hypertrophy in lower limb bypass grafts

Background

Venous grafts commonly develop myointimal hyperplasia, which can lead to stenoses and, ultimately, with expression of adhesion molecules, lumenal occlusion. The aim of the present study was to investigate whether wall shear stress measured post-operatively would predict subsequent myointimal hypertrophy in lower limb venous bypass grafts.

Methods

Magnetic resonance imaging and ultrasound were performed in a cohort of patients following lower limb venous bypass graft surgery for peripheral arterial disease at baseline (1-2 weeks) and at follow-up (9-12 months). Wall shear stress was determined at baseline using computational fluid dynamics techniques and intima-media thickness along the length of the graft was measured by ultrasound at baseline and follow up.

Results

Complete follow-up was possible in eight patients, in whom low wall shear stress at baseline predicted high intima-media thickness. The relationship between wall shear stress (WSS) and intima-media thickness (IMT) was curvilinear with IMT increasing sharply at lower levels of WSS (IMT >1.0 mm at <0.3 Pa).

Conclusions

Low wall shear stress is associated with subsequent increase in myointimal thickness in lower limb venous bypass grafts. This is believed to be the first prospective study in humans to demonstrate the relationship between low wall shear stress and myointimal thickening and indicates a likely causative role for low wall shear stress in the development of myointimal hyperplasia.

Circulating oxidized low-density lipoprotein: a biomarker of atherosclerosis and cardiovascular risk?

Low-density lipoproteins (LDLs) are susceptible to structural modifications by oxidation, particularly the small dense LDL particles. The formation of lipid peroxidation derivates, such as thiobarbituric reactive substances, conjugated dienes, lipid hydroperoxides, and aldehydes, is associated with changes in apolipoprotein conformation and affects the functional properties of LDLs. Oxidized LDL (oxLDL) formation in the subendothelial space of the arterial wall is a key initiating step in atherosclerosis because it contributes to foam cell generation, endothelial dysfunction, and inflammatory processes. In the last decade, immunoassays were developed using monoclonal antibodies against oxidation-dependent epitopes of LDL which made it possible to directly measure oxLDL in the circulation. Increased circulating oxLDL concentrations have been related to cardiovascular disease in some studies, although not always independently after adjustment of classical lipid markers. The Asklepios Study, investigating 2524 healthy middle-aged subjects, showed that circulating oxLDL is affected by many biological and lifestyle factors, as well as (generalized) subclinical atherosclerosis.

Clin Chem Lab Med 2009;47:128–37.