S.J.H. Bredie

Retinal vein occlusion: A form of venous thrombosis or a complication of atherosclerosis? A meta-analysis of thrombophilic factors

Previous studies have shown an increased risk of retinal vein occlusion (RVO) in patients with hypertension, hypercholesterolemia and diabetes mellitus. Literature on the association between thrombophilic factors and RVO consists of small studies and case reports. The objective was to determine the relationship between thrombophilic risk factors and RVO. Thrombophilic risk factors analyzed were hyperhomocysteinemia, MTHFR gene mutation, factor V Leiden mutation, protein C and S deficiency, antithrombin deficiency, prothrombin gene mutation, anticardiolipin antibodies and lupus anticoagulant. For all currently known thrombophilic risk factors odds ratios for RVO were calculated as estimates of relative risk. The odds ratios were 8.9 (95% CI 5.7 - 13.7) for hyperhomocysteinemia, 3.9 (95% CI 2.3 - 6.7) for anticardiolipin antibodies, 1.2 (95% CI 0.9 - 1.6) for MTHFR, 1.5 (95% CI 1.0 - 2.2) for factor V Leiden mutation and 1.6 (95% CI 0.8 - 3.2) for prothrombin gene mutation. In conclusion, regarding thrombophilic risk factors and RVO there is only evidence for an association with hyperhomocysteinemia and anticardiolipin antibodies, factors that are known as risk factors for venous thrombosis as well as for arterial vascular disease. The minor effect of factor V Leiden mutation and the protrombin gene mutation (risk factors for venous thrombosis only) suggests that atherosclerosis might be an important factor in the development of CRVO.

The effect of concentrated n-3 fatty acids versus gemfibrozil on plasma lipoproteins, low density lipoprotein heterogeneity and oxidizability in patients with hypertrygliceridemia

We evaluated in a double-blind randomized trial with a double-dummy design in 28 patients with primary hypertriglyceridemia, the effect of gemfibrozil (1200 mg/day) versus Omacor (4 g/day), a drug containing the n-3 fatty acids eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), on lipid and lipoprotein levels, low density lipoprotein (LDL) subfraction profile and LDL oxidizability. Both Omacor and gemfibrozil therapy resulted in a similar significant decrease in serum triglyceride (TG), very low density lipoprotein (VLDL) triglyceride and VLDL cholesterol concentrations and an increase in high density lipoprotein (HDL) and LDL cholesterol concentrations. The increase in LDL cholesterol was due to a significant increase in cholesterol content of the relatively buoyant LDL subfractions LDL1, LDL2 and LDL3, whereas the relative contribution of the dense LDL subfractions LDL4 and LDL5 to total LDL tended to decrease. So, both therapies resulted in a more buoyant LDL subfraction profile, reflected by a significant increase of the value of parameter K (+10.3% on Omacor vs. +26.5% on gemfibrozil therapy, gemfibrozil vs Omacor P>0.05). Cu(2+)-induced oxidation of LDL was measured by continuous monitoring of conjugated dienes. After 12 weeks of Omacor treatment LDL appeared more prone to oxidative modification in vitro than LDL after gemfibrozil treatment, as measured by the significantly decreased lag time, preceding the onset of the lipid peroxidation. In both groups the rate of oxidation did not change with therapy. The amount of dienes formed during oxidation increased significantly on Omacor treatment, but not on gemfibrozil treatment. Plasma thiobarbituric acid reactive substances were higher after Omacor and lower after gemfibrozil treatment, although not significantly. We conclude that both Omacor and gemfibrozil have favorable effects on lipid and lipoprotein concentrations and the LDL subfraction profile. However, Omacor increased the susceptibility of LDL to oxidation, whereas gemfibrozil did not affect the resistance of LDL to oxidative modification in vitro. The clinical relevance of these changes remains to be established in the light of other postulated favorable effects of n-3 fatty acids on the course of cardiovascular disease.

In Vivo Imaging of Abdominal Aortic Aneurysms: Increased FDG Uptake Suggests Inflammation in the Aneurysm Wall

Purpose: To study the potential of integrated positron emission tomography and computed tomography (PET/CT) to identify aneurysm wall inflammation. Methods: The level of F18-fluorodeoxyglucose (FDG) uptake was studied in aneurysmal and normal-sized aortas of 34 male patients [17 with abdominal aortic aneurysm (AAA) and 17 age-matched controls] identified in a database of 278 consecutive patients evaluated for staging of primary lung cancer. The maximal standardized uptake value (SUV) was calculated to quantify FDG uptake in the AAA wall. Results: AAAs showed significantly higher FDG uptake than the normal-sized aorta in age-matched controls (SUV 2.52±0.52 versus 1.78±0.45, respectively; p<0.001). The level of FDG uptake did not correlate with maximal aneurysm diameter (r=0.09; 95% CI −0.42 to 0.56; p=0.7). Conclusion: FDG-PET/CT is a promising technique to identify inflammation of the aneurysm wall. Irrespective of aneurysm diameter, asymptomatic AAAs show more FDG uptake and more inflammatory activity in the wall than the non-dilated abdominal aorta of sex/age-matched controls. Future studies will be directed at the predictive value of increased FDG uptake for aneurysm wall strength, rupture risk, and the utility of FDG-PET/CT in assessing the effect of medical interventions.

Increased Levels of Low-Density Lipoprotein Oxidation in Patients with Familial Hypercholesterolemia and in End-Stage Renal Disease Patients on Hemodialysis

Patients with familial hypercholesterolemia (FH) and patients with end-stage renal disease (ESRD) undergoing dialysis suffer from accelerated atherosclerosis. Oxidation of low-density lipoprotein (LDL) cholesterol is crucial in atherogenesis. In the present study, we determined the LDL oxidation level and oxidizability of isolated LDL of 11 male patients with FH, 15 male ESRD patients on hemodialysis, and 15 age-matched male normolipidemic healthy controls. FH patients were without lipid-lowering medication for at least 4 weeks and were reassessed after 2 years of cholesterol-lowering therapy (statins). LDL oxidation level was measured by ELISA using monoclonal antibody 4E6 to oxidized LDL (oxLDL) as the capture antibody and anti-human apoB antibody for detection; results were expressed as percentage oxLDL. In FH patients and in ESRD patients on hemodialysis, both groups having a higher percentage of cardiovascular disease, mean plasma LDL oxidation levels were significantly elevated compared with controls (4.9 ± 1.3; 3.7 ± 2.0; 1.7 ± 0.6%, respectively). Within each group of subjects, LDL oxidation level was not associated with history of cardiovascular disease. Furthermore, in neither group was a significant correlation found between plasma concentration of LDL cholesterol and LDL oxidation level. After cholesterol-lowering therapy, LDL oxidation level in FH patients had not changed significantly and remained elevated compared with controls, despite a reduction of LDL cholesterol by 55% on average. Also, absolute plasma oxLDL concentrations, obtained by multiplying LDL oxidation level with plasma LDL cholesterol concentration, were significantly higher in FH patients before and after cholesterol-lowering therapy and in ESRD patients on hemodialysis than in controls (489 ± 145; 189 ± 122; 100 ± 65; and 59 ± 27 μmoles/L, respectively). No correlation was found between plasma oxLDL concentration and parameters of LDL oxidizability, LDL fatty acids, and LDL alpha-tocopherol content. We conclude that cholesterol-lowering therapy does not normalize elevated LDL oxidation levels in FH patients and elevated LDL oxidation level in FH and in ESRD might mirror atherosclerosis.

Segregation analysis of plasma apolipoprotein B levels in familial combined hyperlipidemia

Familial combined hyperlipidemia (FCH) is a heritable lipid disorder that is associated with an increased risk of premature cardiovascular disease. An elevated plasma apolipoprotein (apo) B concentration is reported to be a diagnostic feature of the disorder. Recently we demonstrated a strong relation between plasma apoB concentrations and the cholesterol concentration in VLDL plus LDL, both elevated in FCH families. Therefore, examination of the inheritance of elevated plasma apoB levels in FCH families may reveal important information about the mechanism responsible for the aggregation of elevated plasma lipids in FCH. This study included 663 Dutch family members in 40 families ascertained through FCH probands. Plasma apoB concentration correlated significantly with apoB-related cholesterol both in the probands and the relatives (r=.83 and r=.90, respectively). Adjustment for age, sex, body mass index, and smoking habits accounted for 35.7% of the variation in apoB levels, and there was strong familial aggregation in adjusted apoB levels in these families. Complex segregation analysis was performed to determine the mechanism of inheritance behind this familial aggregation. The aggregation of elevated apoB levels was best explained by a major gene effect inherited by a codominant mechanism. Estimated mean apoB levels for the three supposed genotypes AA, AB, and BB were 111.5, 126.7, and 165.7 mg/dL, respectively, with relative frequencies of 43.5%, 44.9%, and 11.6%, respectively. In conclusion, despite assumed metabolic and genetic heterogeneity of FCH, there is clear evidence for a single gene effect on apoB concentrations in families ascertained through FCH. Linkage studies based on this analysis may further clarify the molecular basis of the apoB regulation in these families.

Enhanced interleukin-10 production by dendritic cells upon stimulation with Toll-like receptor 4 agonists in systemic sclerosis that is possibly implicated in CCL18 secretion

Background: It has been suggested that the T‐cell attracting and profibrotic chemokine CCL18 might play a role in the pathogenesis of systemic sclerosis (SSc). However, it is unclear what underlies the higher CCL18 levels in SSc. The aim of our study was to determine whether Toll‐like receptor (TLR)‐mediated stimulation of monocytes and dendritic cells (DCs) contributes to the higher levels of CCL18 in SSc. Methods: CCL18 levels were measured in 40 patients with SSc, primary Raynauds phenomenon (RP) and healthy controls. The presence of TLR4 agonists in the circulation of SSc patients was investigated using TLR4 transgenic Chinese hamster ovary (CHO) cells. CCL18 and interleukin (IL)‐10 secretion by monocytes/macrophages and monocyte‐derived DCs (moDCs) was measured in the supernatant. The indirect effect of lipopolysaccharide (LPS)‐stimulated moDCs on CCL18 secretion by monocytes/macrophages was investigated using a transwell system. Results: CCL18 levels were significantly elevated in SSc patients compared to patients with RP and healthy controls. SSc sera strongly induced CD25 expression on CHO cells genetically modified to express TLR4 but not on those expressing CD14 only. By contrast, serum from systemic lupus erythematosus (SLE) patients or healthy individuals did not have an effect. Neither monocytes/macrophages nor moDCs from SSc patients secreted higher levels of CCL18 compared to healthy controls. However, moDCs matured with the TLR4 ligand LPS from patients with SSc did secrete significantly higher amounts of IL‐10 compared to those from healthy counterparts, which were IL‐10 dependent. Conclusions: Our results suggest that elevated CCL18 levels in SSc are not caused by an intrinsically enhanced CCL18 secretion by monocytes/macrophages but are, at least partly, orchestrated by an enhanced IL‐10 secretion by TLR4‐stimulated DCs. These observations suggest a role for TLR4 ligands and DCs in the pathogenesis of SSc, a topic that warrants further investigation.

Gender-related association between the −93T→G/D9N haplotype of the lipoprotein lipase gene and elevated lipid levels in familial combined hyperlipidemia

Familial combined hyperlipidemia (FCHL) is a frequent cause of premature coronary artery disease. Affected family members are characterized by different combinations of elevated cholesterol and/or triglyceride levels. A reduction in lipoprotein lipase (LPL) activity has been observed in a subgroup of FCHL patients. Recently, we have demonstrated an increased frequency of mutations in the LPL gene in Dutch FCHL patients compared to normolipidemic controls. In the present study, we have applied a pedigree-based maximum likelihood method to study the effect of LPL mutations on the phenotypic expression of FCHL in families. In 40 FCHL probandi, three different previously reported mutations in the LPL gene were identified resulting in amino acid changes, D9N, N291S, and S447X. The D9N mutation in exon 2 appeared to be in strong linkage disequilibrium with a T-->G substitution at position -93 in the promoter region of the LPL gene. We present data that the -93T-->G/D9N haplotype is associated with significantly higher levels of LDL and VLDL cholesterol, and VLDL triglycerides. Interestingly, the effect was only observed in male carriers. In line with our previous observations, these results further sustain that the LPL gene is a susceptibility gene for dyslipidemia which explains part of the variability in the phenotype observed among FCHL family members.

The Redox Status of Coenzyme Q10 in Total LDL as an Indicator of In Vivo Oxidative Modification: Studies on Subjects With Familial Combined Hyperlipidemia

Familial combined hyperlipidemia (FCH) is characterized by a familial occurrence of a multiple-type hyperlipidemia, associated with coronary risk. The latter may be related to increased levels of small, dense LDL particles that have been found to be more prone to oxidative modification. We isolated total LDL as fresh as possible from 12 normolipidemic relatives with a buoyant LDL subfraction profile (group 1), 7 normolipidemic subjects with a dense LDL subfraction profile (group 2), and 16 hyperlipidemic FCH subjects with a dense LDL subfraction profile (group 3). In these nonobese and normotensive men, we studied the resistance of total LDL against Cu(2+)-oxidation in vitro. In addition, we analyzed the alpha-tocopherol and the coenzyme Q10 contents of LDL and determined their relation to LDL oxidizability. LDL isolated from group 3 subjects was more susceptible to oxidative modification than LDL from group 1 subjects (lag time: 60.4 +/- 8.1 versus 70.4 +/- 11.4 minutes; P < .05). For the combined groups, the ratio of ubiquinol-10 to polyunsaturated fatty acids in LDL, together with the basal amount of dienes in LDL, were good predictors of the rate of LDL oxidation (R2 = .73, P = .0001). In groups 2 and 3, the redox status of coenzyme Q10 (ubiquinol-10/ubiquinone-10) and the ratio of ubiquinol-10 to alpha-tocopherol in LDL were reduced compared with group 1 (P < .05). The K-value a measure of the LDL density, correlated with the the redox status (r = .37, P < .05). We conclude that in subjects with FCH total LDL is more prone to oxidation, due to the predominance of dense LDL particles. In addition, the decreased redox status of coenzyme Q10 in LDL from subjects with a dense LDL subfraction profile suggests that the LDL in the circulation has already undergone some oxidation.

Effectiveness of Nurse Based Motivational Interviewing for smoking cessation in high risk cardiovascular outpatients: a randomized trial.

Objective: To evaluate the feasibility and effectiveness of Nurse Based Motivational Interviewing (NBMI) on top of a routine patient based Lifestyle Inventory with Feedback (LIFE) in a cardiovascular outpatient secondary prevention setting. Methods: All current smokers (n = 112), identified in 619 successive patients with cardiovascular disease, were randomized for either care as usual (LIFE), or LIFE plus NBMI (intervention group). Cumulative time investment was recorded. Results: After 3 months of follow-up, the abstinence rate in the control group was 7%, and another 15% diminished the number of cigarettes, whereas 26% of intervention patients quit smoking (p < 0.017) and another 31% diminished smoking. On average, each completed motivational interviewing session took 63.5 min. Per quitter, time investment was 3.8 h and NNT appeared 5.9. Conclusion: NBMI strategy on top of routinely administrated lifestyle self evaluation with professional feedback, significantly increases smoking cessation in an outpatient secondary prevention setting. Although cost effectiveness needs to be addressed, time investment per quitter in this approach appears low.

Apolipoprotein E polymorphism influences lipid phenotypic expression, but not the low density lipoprotein subfraction distribution in familial combined hyperlipidemia

The impact of apo E polymorphism on interindividual variation in plasma lipid, lipoprotein concentrations, and LDL subfraction profiles was studied in 201 well-defined patients (88 men and 103 women) with familial combined hyperlipidemia (FCH). When corrected for the concomitant influences of age, gender and obesity, the allelic variation in the apo E gene was shown to explain a statistically significant portion of the variability in lipid and (apo)lipoprotein concentrations. Carriers of the apo epsilon 2 allele exhibited a substantially higher plasma triglyceride concentration and a lower low density lipoprotein (LDL) cholesterol level, while subjects with the apo epsilon 4 allele had significant higher total plasma cholesterol and LDL cholesterol levels. In line with this observation, our FCH population was characterized by an over-representation of the apo E4 allele as compared with a Dutch standard population (chi 2 = 55.2, P < 0.0001). The contribution of apo E polymorphism to trait variability was different between sexes for plasma triglyceride, VLDL cholesterol, VLDL triglycerides, and high density lipoprotein (HDL) cholesterol levels. Apo E polymorphism had no impact on chemical composition of VLDL; for LDL particles the apo epsilon 2 allele was associated with a lower cholesterol to protein (C/P) ratio, whereas the opposite was true for the apo epsilon 4 allele. Despite the demonstrated impact of apo E polymorphism on plasma lipids and LDL chemical composition, in all phenotypic groups a dense LDL subfraction profile predominated. Thus, apo E polymorphism contributes to the lipid phenotypic expression in FCH, whereas further evidence was obtained that a dense LDL subfraction profile is an integral feature of FCH.