Jan Dirk Banga

Heterozygosity for a Hereditary Hemochromatosis Gene Is Associated With Cardiovascular Death in Women

Background-The genetic background of hereditary hemochromatosis (HH) is homozygosity for a cysteine-to-tyrosine transition at position 282 in the HFE gene. Heterozygosity for HH is associated with moderately increased iron levels and could be a risk factor for cardiovascular death. Methods and Results-We studied the relation between HH heterozygosity and cardiovascular death in a cohort study among 12 239 women 51 to 69 years of age residing in Utrecht, the Netherlands. Women were followed for 16 to 18 years (182 976 follow-up years). The allele prevalence of the HH gene in the reference group was 4.0 (95% CI 2.9 to 5.4). The mortality rate ratios for HH heterozygotes compared with wild types was 1.5 (95% CI 0.9 to 2.5) for myocardial infarction (n=242), 2.4 (95% CI 1.3 to 3. 5) for cerebrovascular disease (n=118), and 1.6 (95% CI 1.1 to 2.4) for total cardiovascular disease (n=530). The population-attributable risks of HH heterozygosity for myocardial infarction and cerebrovascular and total cardiovascular death were 3. 3%, 8.8%, and 4.0%, respectively. In addition, we found evidence for effect modification by hypertension and smoking. Conclusions-We found important evidence that inherited variation in iron metabolism is involved in cardiovascular death in postmenopausal women, especially in women already carrying classic risk factors.

Nitric oxide availability in diabetes mellitus

Diabetes mellitus is associated with early development of cardiovascular complications. Under physiological conditions the endothelium protects against the development of atherosclerosis. Endothelial cells produce, e.g., nitric oxide (NO), a substance which is capable of keeping vascular tone, coagulation and inflammation well balanced. However, in pathological conditions, such as in diabetes mellitus, impaired NO activity may be present. Decreased NO activity can be caused by impaired production of NO, due to uncoupling of receptor-mediated signal transduction, a deficiency of the NO synthase (NOS) substrate L-arginine, or a decreased availability of one or more cofactors essential for optimal functioning of NOS. However, hyperglycaemia also stimulates the production of advanced glycosylated end products, enhances the polyol pathway and activates protein kinase C. These conditions may lead to increased oxidative stress. Reactive oxygen species rapidly inactivate NO leading to the formation of peroxynitrite. Peroxynitrite is a toxic oxidant capable of damaging many biological molecules. Reduced NO availability may not only be of relevance to the development of atherosclerotic complications in diabetes but may also interfere with insulin-mediated postprandial glucose disposal and possibly contribute to the development of insulin resistance. Understanding of the complex metabolic disturbances interacting with the NO system may provide us with further therapeutic options to decrease cardiovascular morbidity and mortality in diabetes mellitus.

Effect of angiotensin-converting enzyme inhibition and angiotensin II type 1 receptor antagonism on postprandial endothelial function.

OBJECTIVES The purpose of this study was to determine whether endothelial dysfunction as a consequence of direct postprandial lipid response might be favorably influenced by angiotensin-converting enzyme inhibitors or angiotensin AT1 receptor antagonists. BACKGROUND Postprandial triglyceride-rich lipoproteins cause endothelial dysfunction. Angiotensin-converting enzyme inhibitors have been shown to improve vascular reactivity. For angiotensin II type 1 receptor antagonists this effect is as yet uncertain. METHODS A randomized, double-blind, placebo-controlled crossover study in 30 healthy volunteers, aged 18 to 33 years, evaluated the effect of quinapril (40 mg daily for two weeks) and losartan (50 mg daily for two weeks) on basal as well as postprandial endothelial function measured noninvasively as percentage diameter change in the brachial artery after reactive hyperemia. Endothelium-independent dilation was measured after nitroglycerine spray sublingual. RESULTS An acute oral fat load impaired endothelial function. Flow-mediated vasodilation (FMD) decreased from a median of 6.2% to 4.2% (p < 0.05). There was no significant difference in preprandial endothelial function after two weeks of treatment with either quinapril or losartan compared with placebo in these healthy volunteers. Both quinapril (FMD 6.4% to 6.3%) and losartan (7.1% to 5.4%) prevented endothelial dysfunction induced by an oral fat load, although the protective effect of quinapril appeared to be more profound. The response to the endothelium-independent vasodilator nitroglycerine was unaltered throughout the study. CONCLUSIONS Both losartan and quinapril prevent endothelial dysfunction induced by triglyceride-rich lipoproteins in healthy volunteers. However, the protective effect of quinapril is more pronounced.

Plasminogen Activator Inhibitor 4G Polymorphism Is Associated With Decreased Risk of Cerebrovascular Mortality in Older Women

BACKGROUND A common 4G allele of a 4G/5G polymorphism in the promoter region of the plasminogen activator inhibitor-1 (PAI-1) gene is associated with increased transcription of the PAI-1 protein, which may lead to decreased fibrinolysis. It has therefore been proposed as a candidate risk factor for myocardial infarction or stroke. METHODS AND RESULTS We studied the relationship between PAI-1 4G/5G genotype and the risk of cardiovascular mortality in a prospective cohort study among 12 239 women initially aged between 52 and 67 years, with a maximum follow-up time of 18 years (153 732 follow-up years). PAI-1 4G/5G genotype was measured in DNA obtained from urine samples, which were collected at baseline, of 498 women who died of a cardiovascular disease and a random sample of 512 women from the same cohort who did not die of cardiovascular disease. The PAI-1 4G/5G genotype was not associated with risk of myocardial infarction or other cardiovascular mortality. However, PAI-1 4G4G homozygotes had a markedly reduced risk of cerebrovascular mortality compared with PAI-1 5G5G homozygotes: the relative risk was 0.4, with a 95% CI of 0.2 to 0.7, whereas the relative risk of cerebrovascular mortality in PAI-1 4G5G heterozygotes compared with PAI-1 5G5G homozygotes was 0.7, with a 95% CI of 0.4 to 1.1. CONCLUSIONS These findings are suggestive of an important contribution of PAI-1 in cerebrovascular pathology, probably via pathways other than fibrinolysis. PAI-1 may protect against destabilization of the atherosclerotic plaque, or it may inhibit neurotoxicity of tissue plasminogen activator in the brain.

Comparing Subcutaneous Danaparoid with Intravenous Unfractionated Heparin for the Treatment of Venous Thromboembolism: A Randomized Controlled Trial

Danaparoid (Org 10172; Organon Scientific Development Group, Oss, the Netherlands), a heparinoid with a mean molecular weight of 5500 d, is obtained from the intestinal mucosa of the pig after removal of heparin. It is a mixture of sulfated glycosaminoglycans with low molecular weight: heparan sulfate (84%), dermatan sulfate (12%), and chondroitin sulfate (4%) [1, 2]. Only a subfraction (4%) of heparan sulfate contains the pentasaccharide sequence, common to heparin and to low-molecular-weight heparins, that has a high affinity to antithrombin III. This subfraction acts through the selective inhibition of factor Xa through antithrombin III, which leads to the inhibition of thrombin generation. The fraction of heparan sulfate with a low affinity for antithrombin III does not affect coagulation factors Xa and IIa but contributes substantially to antithrombotic activity, probably through an endothelial cellular mechanism [3]. The dermatan sulfate component of danaparoid activates heparin cofactor II, which acts at the level of factor IIa. The synergistic activity of these three components determines the antithrombotic profile. As reflected in its anti-factor Xa:anti-factor IIa inhibitory ratio of more than 28:1, danaparoid is a more selective inhibitor of factor Xa than heparin or the low-molecular-weight heparins. The dose-related response to danaparoid remains gradual and linear over a wide dosing range, which may contribute to its safety as an antithrombotic drug. Compared with heparin and low-molecular-weight heparins, danaparoid has almost no effect on physiologic platelet function and has low cross-reactivity with heparin-induced antibodies against platelets. The wide therapeutic range of danaparoid and its minimal effect on platelets may render it a safer anticoagulant than heparin or low-molecular-weight heparins. Treatment with unfractionated heparin is limited by the drugs pharmacokinetic, biophysical, and antihemostatic (nonanticoagulant) properties. Heparin must be given in sufficient quantities under frequent monitoring, its dose-response curve is nonlinear and unpredictable in individual persons, and the risk for bleeding increases with increasing doses and duration of treatment. Danaparoid has been shown in animal studies to be more effective than standard heparin or two different low-molecular-weight heparin preparations in preventing the extension of experimentally induced venous thrombi [4]. It has been both safe and effective in the prophylaxis of deep venous thrombosis in patients having cancer surgery [5], hip-fracture surgery [6], or hip-replacement surgery [7] and in patients with nonhemorrhagic stroke [8]. It has been used as an anticoagulant during hemodialysis [9, 10] and in patients with heparin-induced thrombocytopenia [11, 12] or disseminated intravascular coagulation [13]. Data from studies of the treatment of deep venous thrombosis in patients with hemorrhagic stroke indicate that treatment with danaparoid can prevent the extension of venous thromboembolism without aggravating cerebral bleeding [14]. No study has yet assessed the efficacy and safety of danaparoid in the treatment of patients presenting with acute deep venous thrombosis or pulmonary embolism. Danaparoid has a bioavailability of 100% after subcutaneous administration; the bioavailability of unfractionated heparin after subcutaneous injection is only 20% to 30%. Therefore, danaparoid is particularly suitable for subcutaneous administration, much like the low-molecular-weight heparin preparations [15-19], which have a bioavailablity of approximately 90%. Our study was designed to assess the efficacy and safety of two doses of subcutaneously administered danaparoid and of continuous intravenous administration of unfractionated heparin as initial treatment in patients presenting with acute proximal deep venous thrombosis of the leg, pulmonary embolism, or both. Methods Study Design Our study was a randomized, open, parallel-group clinical trial done in one university hospital and two university-affiliated hospitals in the Netherlands. The study protocol and forms giving informed consent were approved by the institutional review board at each hospital. Patients All patients gave witnessed informed consent before being entered into the study. Men and women 18 years of age or older who presented with clinical symptoms of acute proximal deep venous thrombosis of the leg or pulmonary embolism of no more than 7 days duration were eligible. Patients were excluded if they had had intracranial bleeding within 2 months or resuscitation by external chest compression within 48 hours; if they were allergic to heparin; if they were pregnant; if they were receiving treatment with coumarin derivatives; if they had been treated with thrombolytic drugs within 7 days; or if they were receiving ongoing treatment with aspirin, nonsteroidal anti-inflammatory drugs, dextran, or fibrinolytic drugs. The provisional diagnosis of venous thrombosis or pulmonary embolism had to be confirmed within 48 hours after the start of study treatment by compression ultrasonography or contrast venography (whichever could be done soonest) or by ventilation-perfusion lung scan. Treatment was discontinued and the patient was excluded from the study if the clinical diagnosis was not confirmed. Enrollment began in March 1991 and continued through August 1992. Dosing Schedule The efficacy and safety of two dosing schedules of danaparoid were compared with the efficacy and safety of continuous intravenous unfractionated heparin. The schedule for low-dose danaparoid was 1250 anti-factor Xa units given as an intravenous bolus, followed by subcutaneous doses of 1250 anti-factor Xa units every 12 hours. The schedule for high-dose danaparoid was 2000 anti-factor Xa units given as an intravenous bolus, followed by subcutaneous doses of 2000 anti-factor Xa units every 12 hours. The first subcutaneous injection was simultaneous with the intravenous bolus injection. The second subcutaneous injection was given at the time of the first of the routine twice-daily injections, unless this was within 6 hours of the first injection. Unfractionated heparin was given intravenously as a loading dose of 2500 U and was followed by an initial maintenance dose of 30 000 U every 24 hours. This maintenance dose was adjusted to reach activated partial thromboplastin 2.5 to 3.5 times the control values; these times were equivalent to a heparin level of 0.25 to 0.40 U/mL. This was measured daily and 4 hours after any dose adjustment. Study treatment was given for at least 5 days and was continued until an international normalized ratio of at least 3.0 was achieved with oral anticoagulation therapy, which was started 48 hours after the initiation of study treatment. The oral anticoagulant dose was calculated daily using the Thrombotest (Nyegaard and Co., Oslo, Norway; international sensitivity index, 0.94); this was done each morning using plasma samples taken before the morning dose had been given. If the international normalized ratio was below the target level after 8 days of study treatment, the attending physician decided whether to continue heparin therapy, continue danaparoid therapy, or switch patients being treated with danaparoid to intravenous heparin. Study treatment was randomized as follows. Consecutively numbered, identical boxes were kept in each hospital pharmacy; each box contained one of the three treatments, randomized per hospital. After giving informed consent, a patient was treated with medication from the next consecutive box. The investigators were blinded to the randomization schedule. Only when the study medication for one individual patient was delivered did the treatment become known. After being assigned to treatment, patients were excluded from the efficacy analysis only if diagnosis of deep venous thrombosis or pulmonary embolism could not be confirmed within 48 hours of admission. Evaluations and Scheduling The primary method of assessment for recurrence or extension was repeated ultrasonography of the leg, contrast venography, ventilation-perfusion scanning, or both contrast venography and ventilation-perfusion scanning. Assessment was done after at least 5 days and at most 8 days of study treatment, within 24 hours after stopping treatment, or if clinically indicated. Institutional physicians, who were blinded to treatment assignments, interpreted venograms, ultrasonograms, and lung scans. Clinical evidence of recurrence or extension was defined as documented clinical circumstances suggestive of venous thromboembolic disease leading to the discontinuation of study treatment. A daily physical examination (including tests for hemoglobin level, platelet count, and leukocyte count) and a urinalysis to test for erythrocyte count were done. Liver function tests were done and creatinine levels were measured before and at the end of study treatment. Plasma used to measure amidolytic anti-factor Xa activity was collected at the time of screening and at treatment days 2 and 4 (before and 2.5 hours after the morning injection on both days). This plasma was frozen at 20C and stored until assay. Plasma samples were collected at the time of screening for determination of activated partial thromboplastin times before study treatment. Follow-up assessment was done 2 months after the initiation of study treatment to gather information on state of health, recurrence or extension of venous thromboembolism, and bleeding complications. Compression Ultrasonography To establish the extent of thrombosis using ultrasonography [20], the deep venous system was divided into six segments: lower popliteal, upper popliteal, inferior femoral, mid-femoral, upper femoral, and common femoral veins. Each patient was first examined in the supine position so that the superficial femoral, common femoral, and iliac vein segments could be assessed. Patients were then examined in the prone position so

Homozygosity for 807 T Polymorphism in α2 Subunit of Platelet α2β1 Is Associated With Increased Risk of Cardiovascular Mortality in High-Risk Women

Background —Platelet adhesion to collagen is the initial step in both hemostasis and thrombosis; this adhesion is mediated by α 2 β 1 on the surface of platelet membranes. An 807 C to T single nucleotide exchange polymorphism close to the gene coding for the α 2 subunit of α 2 β 1 is associated with the density of α 2 β 1 on the platelet membrane. Methods and Results —We studied the relation of the α 2 β 1 807 C/T genotype to cardiovascular mortality in a prospective cohort study of 12 239 women who were invited for the breast cancer screening program of Utrecht, the Netherlands. The initial age was between 52 and 67 years. Women were followed on vital status between 1976 and 1995 (168 513 women-years). Data were analyzed by using a nested case-control design. The α 2 β 1 807 C/T genotype was not associated with cardiovascular mortality in the total population: the rate ratio for cardiovascular mortality in 807 TT homozygotes compared with 807 CC wild types was 1.2 (95% CI 0.8 to 1.7). However, the α 2 β 1 807 T polymorphism was associated with an increased risk of cardiovascular mortality in women who smoked or in women who had indications of compromised endothelium, such as diabetes and microalbuminuria. In those who were exposed to ≥2 of these factors, the risk ratio (95% CI) between α 2 β 1 807 TT homozygotes and 807 CC wild types was 14.1 (5.0 to 39.9). Conclusions —α 2 β 1 807 TT homozygosity, coding for increased α 2 β 1 density on the platelet membrane, is associated with an increased risk of cardiovascular mortality in those women with indications of compromised endothelium.

Effect of statin versus fibrate on postprandial endothelial dysfunction: role of remnant-like particles

BACKGROUND Postprandial lipemia is associated with endothelial dysfunction. Remnant-like particles (RLP) have been suggested to contribute to these adverse vascular effects. We investigated the effect of cerivastatin and gemfibrozil upon oral fat load induced changes in endothelial function and postprandial lipid profile in vivo. METHODS In a randomized cross-over trial, 15 healthy volunteers received cerivastatin (0.4 mg once daily), gemfibrozil (900 mg once daily) or placebo for 3 weeks. Lipid profiles and flow mediated dilation (FMD) were assessed before and 4 h after an oral fat load. Endothelium-independent dilation was tested after nitroglycerine 0.4 mg sublingual spray. RESULTS After the placebo period, the oral fat load induced an increase in triglycerides (TG) and RLP-cholesterol (RLP-C) (0.9 +/- 0.7 and 0.08 +/- 0.04 mmol/l, respectively) and a significant decrease in FMD (9.1 +/- 3.4 to 4.3 +/- 3.3%, P < 0.05). After gemfibrozil, TG increase was attenuated (0.5 +/- 0.5 mmol/l), whereas RLP-C increase (0.05 +/- 0.09 mmol/l) and FMD decrease (9.0 +/- 3.8 to 5.2 +/- 2.6%, P < 0.05) were not different from placebo therapy. Cerivastatin did not affect TG increase (0.7 +/- 0.8 mmol/l). RLP-C increase (0.02 +/- 0.07 mmol/l) and FMD (7.9 +/- 2.6 to 8.4 +/- 2.8%) change were attenuated significantly compared to placebo. Endothelium-independent vasodilatation remained unaltered throughout the protocol. CONCLUSION Cerivastatin, but not gemfibrozil significantly reduces RLP-C increase after an oral fat load in combination with a reversal of fat-load induced endothelial dysfunction. The present data imply that lowering of RLP-C, rather than lowering of total TG levels, may contributes to the prevention of endothelial dysfunction after an oral fat load during statin use.

Is plaque formation in the common carotid artery representative for plaque formation and luminal stenosis in other atherosclerotic peripheral arteries? A post mortem study

The atherosclerotic carotid artery is easily accessible for non-invasive duplex investigation. The aim of the present post mortem study was to examine whether plaque accumulation and luminal stenosis in the common carotid artery is representative for atherosclerotic plaque accumulation and luminal stenosis in other peripheral arteries. A total of 3765 cross-sections were obtained at regular intervals from 240 arteries (24 individuals). Five types of peripheral arteries were investigated: common carotid, femoral, common iliac, external iliac and renal arteries. In each cross-section, the lumen area, vessel area, plaque area and maximal plaque thickness was measured. For each location, the percentage luminal stenosis and relative plaque area was calculated. Relative plaque area was defined as the percentage of the vessel area which was occupied by plaque. Weak correlations (r=0.41-0.59) were observed between percentage relative plaque area or maximal plaque thickness in the common carotid artery and percentage relative plaque area in other peripheral arteries. Neither plaque accumulation nor luminal stenosis in the common carotid artery correlated with the percentage luminal stenosis in other peripheral arteries (P > 0.05). We conclude that plaque area in the common carotid artery is weakly correlated with plaque area and not correlated with luminal stenosis in other peripheral arteries.

Effect of intensive lipid-lowering strategy on low-density lipoprotein particle size in patients with type 2 diabetes mellitus

A preponderance of small dense LDL particles is strongly associated with the occurrence of atherosclerotic disease. Although several studies have documented an increased prevalence of small dense LDL particles in diabetes mellitus no data are available to show the effect of lipid-lowering treatment upon the improvement of LDL particle size. In the present study we examined the effect of lipid-lowering treatment, following an intensive lipid-lowering strategy for 30 weeks pursuing ADA recommended target lipid levels, on LDL particle size in 50 type 2 diabetic patients with moderate hyperlipidemia. At week 0, 24 patients (48%) were characterized by small dense LDL phenotype pattern B. After the treatment period a shift towards normal LDL particle size was observed in 17 patients but seven patients (29%) showed the more atherogenic LDL subclass pattern B. After treatment, plasma HDL-cholesterol was significantly lower (P<0.05) in these patients compared to those who had LDL subclass pattern A. Multivariate regression analysis revealed VLDL-cholesterol or triglycerides and HDL(3)-cholesterol as independent determinants for LDL particle size. Change in HDL(2)-cholesterol was an independent determinant for change in LDL particle size. In conclusion, a strategy of intensive lipid-lowering, with the intention to reduce triglyceride levels below 1.7 mmol/l, may be insufficient to ensure improvement in LDL size in all patients.

Long-term treatment of hypercholesterolemia with fluvastatin: A 52-week multicenter safety and efficacy study

Abstract In this long-term (52-week) open-label extension to an earlier randomized, multicenter, double-blind, placebo-controlled, dose-finding trial, 381 patients with primary hypercholesterolemia received fluvastatin at increasing doses of 10 to 40 mg/day to achieve plasma low-density lipoprotein (LDL) cholesterol normalization, according to the European Atherosclerosis Society guidelines. The aim of the extension study was to assess the long-term efficacy, safety, and tolerability of fluvastatin. After 52 weeks of therapy, 75% of patients were receiving fluvastatin at 40 mg/day (mean dose: 36 ± 8 mg/day). The mean percent change in LDL-cholesterol levels from baseline was −24.8% (p