New candidate genes for ST-elevation myocardial infarction.

BACKGROUND: Despite extensive research in atherosclerosis, the mechanisms of coronary atherothrombosis in ST-elevation myocardial infarction (STEMI) patients are undetermined. OBJECTIVES: Our aim was to find candidate genes involved in STEMI by analysing leucocyte gene expression in STEMI patients, without the influence of secondary inflammation from innate immunity, which was assumed to be a consequence rather than the cause of coronary atherothrombosis. METHODS: Fifty-one patients were included at coronary angiography because of STEMI. Arterial blood was sampled in the acute phase (P1), at 24-48 h (P2) and at 3 months (P3). Leucocyte RNA was isolated and gene expression analysis was performed by Affymetrix Human Transcriptome Array 2.0. By omission of up- or downregulated genes at P2, secondary changes from innate immunity were excluded. Genes differentially expressed in P1 when compared to the convalescent sample in P3 were determined as genes involved in STEMI. RESULTS: Three genes were upregulated at P1 compared to P3; ABCG1 (P = 5.81 × 10-5 ), RAB20 (P = 3.69 × 10-5 ) and TMEM2 (P = 7.75 × 10-6 ) whilst four were downregulated; ACVR1 (P = 9.01 × 10-5 ), NFATC2IP (P = 8.86 × 10-5 ), SUN1 (P = 3.87 × 10-5 ) and TTC9C (P = 7.18 × 10-6 ). These genes were also highly expressed in carotid atherosclerotic plaques. CONCLUSIONS: We found seven genes involved in STEMI. The study is unique regarding the blood sampling in the acute phase and omission of secondary expressed genes from innate immunity. However, the results need to be replicated by future studies.

Use of proteomics to identify biomarkers associated with chronic kidney disease and long-term outcomes in patients with myocardial infarction.

BACKGROUND: Patients with chronic kidney disease (CKD) have poor outcomes following myocardial infarction (MI). We performed an untargeted examination of 175 biomarkers to identify those with the strongest association with CKD and to examine the association of those biomarkers with long-term outcomes. METHODS: A total of 175 different biomarkers from MI patients enrolled in the Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART) registry were analysed either by a multiple reaction monitoring mass spectrometry assay or by a multiplex assay (proximity extension assay). Random forests statistical models were used to assess the predictor importance of biomarkers, CKD and outcomes. RESULTS: A total of 1098 MI patients with a median estimated glomerular filtration rate of 85 mL min-1 /1.73 m2 were followed for a median of 3.2 years. The random forests analyses, without and with adjustment for differences in demography, comorbidities and severity of disease, identified six biomarkers (adrenomedullin, TNF receptor-1, adipocyte fatty acid-binding protein-4, TNF-related apoptosis-inducing ligand receptor 2, growth differentiation factor-15 and TNF receptor-2) to be strongly associated with CKD. All six biomarkers were also amongst the 15 strongest predictors for death, and four of them were amongst the strongest predictors of subsequent MI and heart failure hospitalization. CONCLUSION: In patients with MI, a proteomic approach could identify six biomarkers that best predicted CKD. These biomarkers were also amongst the most important predictors of long-term outcomes. Thus, these biomarkers indicate underlying mechanisms that may contribute to the poor prognosis seen in patients with MI and CKD.

Morbidity and cause-specific mortality in first-time myocardial infarction with nonobstructive coronary arteries.

BACKGROUND: Myocardial infarction (MI) with nonobstructive coronary arteries (MINOCA) is receiving increasing interest as a prognostically adverse entity distinct from myocardial infarction with significant coronary artery disease (MI-CAD). However, data are still limited regarding long-term cardiovascular morbidity and cause-specific mortality in MINOCA. METHODS: This is a registry-based cohort study using data from patients admitted to Swedish coronary care units. We investigated various nonfatal outcomes (recurrent MI, hospitalization for heart failure or stroke) and fatal outcomes (cardiovascular, respiratory or cancer-related mortality) in 4069 patients without apparent acute cardiovascular disease, used as non-MI controls, 7266 patients with first-time MINOCA and 69 267 patients with first-time MI-CAD. RESULTS: Almost all event rates (median follow-up 3.8 years) increased in a stepwise fashion across the three cohorts [rates of major adverse events (MAE; composite of all-cause mortality, recurrent MI, hospitalization for heart failure or stroke): n = 268 (6.6%), n = 1563 (21.5%), n = 17 777 (25.7%), respectively]. Compared to non-MI controls, MINOCA patients had an adjusted hazard ratio (HR) of 2.12 (95% confidence interval 1.84-2.43) regarding MAE. MINOCA patients had a substantial risk of cardiovascular mortality and the highest numerical risks of respiratory and cancer-related mortality. Male sex, previous heart failure and chronic obstructive pulmonary disease had a stronger prognostic impact in MINOCA than in MI-CAD. Female MINOCA patients with atrial fibrillation were at particular risk. CONCLUSIONS: Patients with first-time MINOCA have a considerable risk of adverse events. This stresses the need for a comprehensive search of the cause of MINOCA, thorough treatment of underlying disease triggers and close follow-up.

Supplemental oxygen therapy does not affect the systemic inflammatory response to acute myocardial infarction.

BACKGROUND: Oxygen therapy has been used routinely in normoxemic patients with suspected acute myocardial infarction (AMI) despite limited evidence supporting a beneficial effect. AMI is associated with a systemic inflammation. Here, we hypothesized that the inflammatory response to AMI is potentiated by oxygen therapy. METHODS: The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) multicentre trial randomized patients with suspected AMI to receive oxygen at 6 L min-1 for 6-12 h or ambient air. For this prespecified subgroup analysis, we recruited patients with confirmed AMI from two sites for evaluation of inflammatory biomarkers at randomization and 5-7 h later. Ninety-two inflammatory biomarkers were analysed using proximity extension assay technology, to evaluate the effect of oxygen on the systemic inflammatory response to AMI. RESULTS: Plasma from 144 AMI patients was analysed whereof 76 (53%) were randomized to oxygen and 68 (47%) to air. Eight biomarkers showed a significant increase, whereas 13 were decreased 5-7 h after randomization. The inflammatory response did not differ between the two treatment groups neither did plasma troponin T levels. After adjustment for increase in troponin T over time, age and sex, the release of inflammation-related biomarkers was still similar in the groups. CONCLUSIONS: In a randomized controlled setting of normoxemic patients with AMI, the use of supplemental oxygen did not have any significant impact on the early release of systemic inflammatory markers.

Myocardial infarction with normal coronary arteries is common and associated with normal findings on cardiovascular magnetic resonance imaging: results from the Stockholm Myocardial Infarction with Normal Coronaries study.

OBJECTIVES: Myocardial infarction with angiographically normal coronary arteries (MINCA) is an important subtype of myocardial infarction; however, the prevalence, underlying pathophysiology, prognosis and optimal management of this condition are still largely unknown. Cardiovascular magnetic resonance (CMR) imaging has the potential to clarify the underlying pathology in patients with MINCA. The objective of this study was to investigate the diagnostic value of CMR imaging in this group of patients. DESIGN: The prospective, multicentre, observational Stockholm Myocardial Infarction with Normal Coronaries (SMINC) study. SETTING: Coronary care units in the Stockholm metropolitan area. SUBJECTS: Patients between 35 and 70 years of age with MINCA were consecutively included in the screening phase of the SMINC study. All patients had a typical clinical presentation, fulfilling the universal definition of myocardial infarction and had normal coronary angiography finding. Patients with known structural or coronary heart disease or other known causes of elevated troponin levels were excluded. RESULTS: In total, 176 patients with MINCA were screened from 2007 to 2011. Of these, 152 underwent CMR imaging. The investigation was performed a median of 12 (interquartile range 6-28) days after hospital admission; 67% of the findings were normal, whereas 19% of patients had signs of myocardial necrosis and 7% had signs of myocarditis. The remaining patients (7%) had either unrecognized hypertrophic cardiomyopathy or could not be classified. CONCLUSION: In this consecutive series of patients with MINCA, CMR imaging may help to differentiate between those with myocarditis, myocardial necrosis and normal myocardium. The incidence of MINCA was higher than previously reported. After excluding cases of myocarditis, MINCA consists of a large group of patients with normal CMR imaging results and a smaller group with myocardial necrosis. The aetiologies of these different imaging findings need to be explored.

Cardiovascular disease associated with radiotherapy: activation of nuclear factor kappa-B.

There have been several recent reports of an increased risk of cardiovascular disease after radiotherapy. Hence, with an increasing number of cancer survivors, the incidence of cardiovascular disease caused by radiotherapy will increase. The existence of a type of vascular disease, or vasculopathy, induced by radiotherapy has been known for decades. It is important to identify and understand the molecular causes of this vasculopathy to determine preventive strategies. Recently, a chronic inflammation with similarities to atherosclerosis has been observed, with activation of the transcription factor nuclear factor kappa-B (NF-κB) as a possible cause. However, the trigger for NF-κB activation is unclear although it may be that reactive oxygen species or direct DNA damage is involved. To minimize the risk of cardiovascular disease in vulnerable patients, careful selection of patients, radiation dose and fractionation are important, together with the development of new techniques that reduce radiation dose to the blood vessels. In the light of the finding of an interaction between risk factors for cardiovascular disease and radiotherapy, it is reasonable to modify these factors including diabetes mellitus, hyperlipidaemia, hypertension and smoking. We believe that preventive strategies focusing on NF-κB can reduce the risk of future adverse cardiovascular events.

Use of the whole leucocyte population in the study of the NFκB pathway.

The nuclear factor NF-{kappa}B (NFκB) is involved in the regulation of innate immunity and in particular, inflammatory genes. It is associated with the pathogenesis of many chronic diseases such as coronary heart disease (CHD). It is believed that individual susceptibility to CHD might be affected by differences in gene transcription and therefore gene expression in circulating cell populations such as leucocytes is of interest. The aim of this study was to investigate whether the total white blood cell population (leucocytes) could be used to study the effect of lipopolysaccharide (LPS) treatment on the expression of genes of the NFκB pathway. Gene expression of the NFκB pathway was examined in total leucocyte, monocyte and neutrophil populations. The majority of the 84 genes examined were up-regulated after treatment with LPS for 12 h in all cell populations examined. The total leucocyte population behaved in a similar manner to both neutrophils and monocytic cells, indicating that it alone could be used in studies, therefore avoiding cell separation, which is time-consuming and can result in cell activation. Furthermore, in clinical studies, it enables a larger number of patient samples to be studied simultaneously, while also reducing the amount of blood required from each. This will provide enough starting material for use with molecular techniques, such as chromatin immunoprecipitation (ChIP) and ChIP-sequencing, and allow large-scale gene expression studies of the NFκB pathway in patients with chronic and acute inflammation with established CHD.

Prevalence and cumulative incidence of cancer, and mortality in patients with Takotsubo syndrome with focus on the index event.

BACKGROUND: It has been suggested that Takotsubo syndrome (TS) is associated with cancer but previous studies have limitations. AIM: To make a comprehensive analysis of prevalence and cumulative incidence of cancer, and mortality among TS patients with focus on the index event. DESIGN: A register-based case-control study. METHODS: The first new cancer occurrences (International Classification of Diseases C00-C75, C81-C96) were compared between 505 patients with TS without obstructive coronary artery disease (CAD) and four age- and gender-matched controls comprising patients with acute coronary syndrome with obstructive CAD (CAD controls), respectively, with chest-pain without obstructive CAD at coronary angiography (controls without CAD). RESULTS: The prevalence of cancer before the index event was non-significantly (P = 0.052) higher in TS patients (15.8%) than in CAD controls (11.5%), respectively, higher (P = 0.028) than in controls without CAD (11.1%). There were no differences between the groups in cumulative incidence of cancer after the index event but a higher mortality in TS patients who developed cancer when compared with controls without CAD that developed cancer after the index event (P = 0.018). CONCLUSIONS: There is an increased prevalence of first diagnosed cancer in TS patients before the index event but no increased cumulative incidence of cancer after the index event. The results does not support investigation for the possibility of a malignancy specifically in TS patients but in the event of cancer this patient group might need special care. However, if there is lack of a clear stressor it could be of importance to investigate the possibility of a malignancy.

Accumulation of apolipoprotein C-I-rich and cholesterol-rich VLDL remnants during exaggerated postprandial triglyceridemia in normolipidemic patients with coronary artery disease.

BACKGROUND: Exaggerated postprandial triglyceridemia is common in normolipidemic patients with coronary artery disease (CAD). Alterations in the composition of triglyceride-rich lipoproteins (TRLs) are likely to underlie this metabolic disturbance. However, the composition of very-low-density lipoproteins (VLDLs), which are the most abundant postprandial TRLs, has never been defined in CAD patients. METHODS AND RESULTS: We examined postprandial changes in the number and composition of VLDLs in middle-aged, normolipidemic CAD patients and control subjects. TRLs from 14 patients and 14 control subjects aged 45 to 55 years were subfractionated by density gradient ultracentrifugation into Svedberg flotation rate (Sf) fractions >400, 60 to 400, and 20 to 60. The VLDLs were separated from chylomicron remnants by immunoaffinity chromatography. In CAD patients, the postprandial concentrations of triglycerides and large (Sf 60 to 400) VLDL particles were elevated. In addition, their postprandial large VLDLs were enriched in apolipoprotein (apo) C-I and their postprandial small (Sf 20 to 60) VLDL remnants were enriched with apo C-I and cholesterol. CONCLUSIONS: Perturbed handling of postprandial triglycerides in normolipidemic CAD patients involves the accumulation of apo C-I-rich large VLDL particles and the generation of small, apo C-I- and cholesterol-rich VLDL remnants.

Mild-to-moderate hypertriglyceridemia in young men is associated with endothelial dysfunction and increased plasma concentrations of asymmetric dimethylarginine.

OBJECTIVES: The aim of this study was to investigate endothelial function and common carotid intima-media thickness (IMT) in healthy young men with mild-to-moderate hypertriglyceridemia. Plasma asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, was measured to further elucidate the mechanisms involved. BACKGROUND: Hypertriglyceridemia is a risk factor for coronary heart disease although the mechanisms behind the increased risk remain to be defined. Acute elevation of plasma triglycerides induced by an intravenous fat load is associated with impaired endothelial function. The results of studies examining acute effects induced by a high-fat meal or effects of chronic hypertriglyceridemia on endothelial function are more inconsistent. METHODS: Flow-mediated vasodilation and nitroglycerin-induced vasodilation of the brachial artery and common carotid IMT were measured noninvasively by ultrasound technique in 15 hypertriglyceridemic (HTG) subjects and 15 matched controls, mean age 34 years. Plasma concentrations of ADMA were measured by high-performance liquid chromatography. RESULTS: Flow-mediated vasodilation was decreased in the HTG group (p < 0.0001), whereas nitroglycerin-induced vasodilation and carotid IMT did not differ significantly. Asymmetric dimethylarginine concentrations were higher in the HTG group (p < 0.05). CONCLUSIONS: Hypertriglyceridemia in young men is associated with endothelial dysfunction and increased plasma concentration of ADMA but not with increased IMT of the common carotid artery. The corollary is that chronic hypertriglyceridemia results in endothelial dysfunction, possibly due to increased ADMA concentration, and that endothelial dysfunction might precede increased IMT among the early manifestations of atherosclerosis.

Skin dose alarm levels in cardiac angiography procedures: is a single DAP value sufficient?

Maximum estimated skin doses to patients undergoing coronary angiography procedures were obtained using radiographic slow film and diode dosemeters. Conversion factors of maximum entrance skin dose versus dose-area product (MESD/DAP) for diagnostic (coronary angiography (CA); 20 patients; 2 operators) and interventional procedures (percutaneous transluminal coronary angiography (PTCA); 10 patients; 1 operator) were 4.3 (mean value of 10 CA; operator A), 3.5 (mean value of 10 CA; operator B) and 9.7 (mean value of 10 PTCA; operator B) mGy(Gycm2)(-1), respectively. The results emphasise a need for both operator- and procedure-specific conversion factors. Compared with a single, global factor for all cardiac procedures and/or operators that is commonly applied today, such a refinement is expected to improve the accuracy in skin dose estimations from these procedures. Consequently, reference DAP values used in the clinic to define patients who could suffer from a radiation induced skin injury following a cardiac procedure, should be defined for each operator/procedure. The film technique was found to be superior to the diode in defining conversion factors in this study, and allowed for a rapid and accurate estimation of MESD for each patient. With appropriate positioning of the diode, a combined film/diode technique has a potential use in the training of new angiography operators. The patient body mass index (BMI) value was a good indicator of the variation in average lung dose (critical organ) between patients. The highest lung dose/DAP value was obtained for normal sized patients (BMI: 19-26), and was close to 1.5 mGy(Gycm2)(-1) with both CA and PTCA procedures.

Myocarditis or "true" infarction by cardiac magnetic resonance in patients with a clinical diagnosis of myocardial infarction without obstructive coronary disease: A meta-analysis of individual patient data.

OBJECTIVE: Myocardial Infarction with Non-Obstructed Coronary Arteries (MINOCA) is common, but the causes are to a large extent unknown. Thus, we aimed to study the prevalence of myocarditis and "true" myocardial infarction determined by cardiac magnetic resonance (CMR) imaging in MINOCA patients, and risk markers for these two conditions in this population. METHODS: A search was made in the PubMed and Cochrane databases using the search terms "Myocardial infarction", "Coronary angiography", "Normal coronary arteries" and "MRI". All relevant abstracts were read and seven of the studies fulfilled the inclusion criteria; studies describing case series of patients fulfilling the diagnosis of acute myocardial infarction with normal or non-obstructive coronary arteries on coronary angiography that were investigated with CMR imaging. Data from five of these studies are presented. RESULTS: A total of 556 patients from 5 different sites were included. Fifty-one percent were men with a mean age of 52 ± 16 years. Thirty-three per cent of the patients had myocarditis (n = 183), whereas 21% of the patients had infarction on CMR (n = 115). Young age and a high CRP were associated with myocarditis whereas male sex, treated hyperlipidemia, high troponin ratio and low CRP were associated with "true" myocardial infarction. CONCLUSION AND RELEVANCE: The results of this meta-analysis of individual data showed that myocarditis and "true" myocardial infarction are common in MINOCA when determined by CMR imaging. This information emphasizes the importance of performing CMR imaging in MINOCA patients and can be used clinically to guide diagnostics and treatment of MINOCA patients.

Inverse relation between the concentration of low-density-lipoprotein vitamin E and severity of coronary artery disease.

Oxidation of low-density lipoprotein (LDL) is believed to play an important role in atherogenesis, and antioxidant vitamins are thought to protect against coronary artery disease (CAD). We investigated whether the vitamin E concentrations in serum and LDL were associated with the severity of CAD as assessed by a semiquantitative scoring system in which coronary angiograms are analyzed for the number and size of distinct stenotic lesions (global stenosis score). The study group consisted of 64 consecutive male survivors of myocardial infarction aged < 45 y. Lipid-adjusted serum and LDL vitamin E concentrations were significantly lower in the patients than in 35 age-matched male control subjects, whereas the absolute serum and LDL vitamin E concentrations did not differ significantly. No associations were found between the serum concentration or lipid-adjusted serum values of vitamin E and the stenosis score. In contrast, significant inverse correlation was found between the LDL vitamin E concentration, whether adjusted to the lipid (r=-0.477,P<0.001) or protein (r=-0.375, P<0.01) content of LDL, and the global coronary stenosis score. We conclude that a low LDL vitamin E concentration might play a role in the development of stenoses in coronary arteries and may contribute to clinically manifest CAD.

The plasminogen activator inhibitor-1 -675 4G/5G genotype influences the risk of myocardial infarction associated with elevated plasma proinsulin and insulin concentrations in men from Europe: the HIFMECH study.

UNLABELLED: Although the potential role of plasminogen activator inhibitor-1 (PAI-1) in the development of coronary artery disease is strongly supported by its biological characteristics, results of clinical studies remain controversial. OBJECTIVES: To investigate whether plasma PAI-1 concentrations and the -675 4G/5G polymorphism located in the PAI-1 gene could constitute risk markers for myocardial infarction (MI). PATIENTS AND METHODS: We used a European case-control study, the HIFMECH study, comparing 598 men with MI and 653 age-matched controls. RESULTS: Insulin resistance explained a major part of the variation in PAI-1 (24%) whereas inflammation had only a minor contribution (0.01%). For both cases and controls plasma PAI-1 concentrations were significantly higher in the North than the South, and in both regions were higher in individuals with MI compared with control subjects [overall odds ratio (OR) for a 1 SD increase=1.54, 95% confidence interval (CI) 1.34, 1.77]. This difference was observed in all the centers studied. Overall, the difference between cases and control subjects remained significant after controlling for inflammation variables (OR=1.30, 95% CI 1.08, 1.57), but lost significance after controlling for insulin resistance variables (OR=1.17, 95% CI 0.98, 1.40). The 4G allele was associated with significantly higher PAI-1 levels in cases but not controls and, taken independently, did not modify the risk of MI (P=0.9). However, a significant interaction was observed with both insulin or proinsulin and the risk of MI (P=0.05 and 0.02, respectively), but not with triglycerides or body mass index (BMI). The insulin or proinsulin effect on risk was observed only in the carriers of the 4G/4G genotype. This interaction appeared not to be mediated by plasma PAI-1 antigen concentrations (P=0.01 and 0.02 after adjustment for PAI-1 plasma levels). The interaction with proinsulin but not insulin remained statistically significant after further adjustment for other factors associated with insulin resistance (triglycerides and BMI) and C-reactive protein (P=0.01). CONCLUSION: This study suggests that PAI-1 has a role in risk of MI in the presence of underlying insulin resistance. A significant interaction between insulin or proinsulin and the -675 4G/5G polymorphism was observed in risk for MI. The mechanisms for these interactions remain to be determined.

Abnormalities of composition and of in vitro lipolysis products of human small very low density lipoproteins in hypertriglyceridemia.

Small (Sf 20-100) very low density lipoprotein (VLDL) particles were prepared by density gradient ultracentrifugation of plasma from normolipidemic and type IV hypertriglyceridemic post-infarction patients and healthy controls. The small VLDL separated from the plasma of severely hypertriglyceridemic post-infarction patients were found to contain twice the amount of cholesteryl esters per particle, compared with small VLDL from normolipidemic patients and healthy controls. There was a linear increase in the percentage of cholesterol that was esterified in the small VLDL with the serum VLDL triglyceride concentration (r = 0.66). When incubated for two hours with bovine lipoprotein lipase in excess and bovine albumin as a free fatty acid acceptor at one and the same triglyceride concentration in the medium, the end-product isolated by ultracentrifugation varied as a function of the serum VLDL triglyceride level. The amount of glyceride-glycerol recovered after two hours of incubation with lipoprotein lipase was 13.3 +/- 1.3% (mean +/- SEM) of the initial values and did not correlate with the VLDL triglyceride level. With rising serum VLDL triglyceride concentration, the product isolated in the low density lipoprotein (LDL) density region (1.006 less than d less than 1.063 kg/l) contained more total cholesterol and phospholipids. The linear correlation coefficients for these relations were 0.65 and 0.58 for cholesterol and phospholipids respectively. The ratio of total cholesterol to insoluble protein in the LDL density range after lipolysis rose with increasing serum VLDL triglyceride level (r = 0.68). The end-product was further characterized by density gradient ultracentrifugation of the incubate. In vitro LDL derived by lipolysis of normolipidemic small VLDL was denser than in vitro LDL of hypertriglyceridemic small VLDL. A significant relation was found between the percentage of cholesteryl esters of total cholesterol in the substrate and the relative amount of total cholesterol recovered in the LDL density fraction after lipolysis (r = 0.69). We suggest that the enrichment with cholesteryl esters of small VLDL from type IV hypertriglyceridemic patients is caused by lipid transfer from LDL and high density lipoprotein (HDL) and that the change in VLDL particle composition influences the precursor-product relationship to LDL.

A triglyceride-rich fat emulsion and free fatty acids but not very low density lipoproteins impair endothelium-dependent vasorelaxation.

OBJECTIVE: To investigate the effects of triglycerides and free fatty acids on endothelium-dependent and endothelium-independent vasorelaxation. METHODS: Femoral arterial rings from rats were studied in organ baths. The vascular segments were constricted with phenylephrine after 20 min of preincubation with the triglyceride-rich fat emulsion Intralipid, free fatty acids (16:0, 18:1, 18:3) bound to bovine serum albumin, or very low density lipoproteins. Endothelium-dependent and endothelium-independent relaxations were determined after administration of acetylcholine and nitric oxide donors, respectively. RESULTS: Preincubation with Intralipid caused a concentration-dependent impairment of endothelium-dependent but not endothelium-independent relaxation. Very low density lipoproteins did not affect vascular function. All free fatty acids impaired endothelium-dependent relaxation, whereas endothelium-independent relaxation was unaffected. Administration of the antioxidant vitamin C partly reversed the impairment of the endothelium-dependent relaxation induced by Intralipid and free fatty acids. CONCLUSIONS: The present study demonstrates that the triglyceride-rich fat emulsion Intralipid and individual FFAs impair endothelium-dependent relaxation of arterial rings from rat, whereas triglycerides in the form of VLDL do not affect endothelial function. The finding that the antioxidant vitamin C partly reverses this impairment indicates the involvement of oxidative mechanisms.

Normalisation of the composition of very low density lipoprotein in hypertriglyceridemia by nicotinic acid.

Large (Sf greater than 100) and small (Sf 100-20) very low density lipoprotein (VLDL) particles were isolated by density gradient ultracentrifugation and characterized chemically in 8 patients with primary hypertriglyceridemia before and after 6 weeks treatment with 4 grammes daily of nicotinic acid (NA). Concomitant changes in high density lipoprotein (HDL) subclass distribution were determined by gradient gel electrophoresis. Small VLDL was subjected to lipolysis in vitro by incubation with bovine lipoprotein lipase before and after NA, and the change in the lipolytic end-product isolated in the low density lipoprotein (LDL) fraction was investigated. Reductions were achieved in the plasma levels of triglycerides, free and esterified cholesterol, phospholipids and proteins in the two VLDL subfractions. In all, the composition of both large and small VLDL particles changed towards potentially less atherogenic particles that were poorer in cholesteryl esters. The HDL cholesterol concentration increased and the HDL protein distribution on gradient gel electrophoresis changed towards larger particles. The mechanism behind the change in cholesterol distribution between VLDL and HDL after NA treatment is unclear, but it could possibly relate to decreased lipid transfer activity. NA reduced the content of apolipoprotein B in both VLDL subclasses and did not decrease the calculated particle size or the number of triglyceride molecules per particle, indicating a reduction of VLDL particle number rather than of particle size. The LDL density fraction isolated after lipolysis in vitro of small VLDL contained less total cholesterol and phospholipids and had a density profile more similar to native LDL after the patients had been treated with NA.

Relationships of low density lipoprotein subfractions to angiographically defined coronary artery disease in young survivors of myocardial infarction.

Low density lipoprotein (LDL) from 36 young post-infarction patients was separated by isopycnic density gradient ultracentrifugation to determine the relationships of plasma levels and chemical composition of different LDL subfractions to the global severity and rate of progression of coronary atherosclerosis assessed by angiography. There were marked elevations of the cholesterol and triglyceride concentrations in the very low density lipoprotein (VLDL) fraction, whereas the high density lipoprotein (HDL) cholesterol level was reduced in the patients compared with 70 healthy population-based controls. Plasma total LDL cholesterol and triglyceride concentrations were similar. The distribution of apolipoprotein B along the LDL density range, viz. the LDL particle distribution, was displaced towards the dense LDL region among the patients compared with 14 healthy normolipidaemic controls. A preponderance of dense LDL particles was associated with elevated plasma VLDL triglyceride concentration. The patients had significantly higher plasma concentrations of lipid and protein in dense LDL (d greater than 1.040 kg/l), while no group differences were found in the light LDL (d less than 1.040 kg/l). However, there were no percentage compositional differences in the light or dense LDL between patients and controls. Among all constituents of lipoprotein fractions and subfractions determined, only the plasma level of triglycerides in both light and dense LDL correlated significantly with the angiographic estimates of global severity and rate of progression of coronary atherosclerosis, respectively. On a percentage composition basis, both light and dense LDL tended to be richer in triglycerides in the subjects with a more severe coronary artery disease. Neither VLDL or HDL, nor LDL cholesterol were associated with the angiographic scores, the plasma LDL triglyceride concentration or the triglyceride enrichment of LDL. Although there is ample experimental evidence that triglyceride-enriched LDL predisposes to atherosclerosis, the LDL associations with coronary lesion severity and progression observed in the present study might not reflect a causal mechanism, but merely mirror the atherogenicity of disturbances affecting the metabolism of triglyceride-rich lipoproteins. Prospective studies of larger groups of unselected patients are needed to corroborate these findings.

Apolipoprotein B gene polymorphisms, lipoproteins and coronary atherosclerosis: a study of young myocardial infarction survivors and healthy population-based individuals.

Association studies were carried out in a sample of 87 patients from Sweden who had survived a myocardial infarction (MI) before the age of 45, and 91 age-matched healthy individuals, to compare the impact of polymorphisms at the apolipoprotein (apo) E and B gene loci on among-individual differences in plasma lipid traits and progression of atherosclerosis. In the group of healthy individuals, polymorphisms creating the common apo E isoforms were, as expected, associated with significant differences in total and low density lipoprotein (LDL) cholesterol (11.7% and 11.6% of sample variance). For apo B, the polymorphism with the largest effect on apo B levels (16% of sample variance) was the C to T transition 265 bp 5' of the cap site, in the promoter (detectable by MspI). Both this polymorphism and the threonine2488 neutral substitution (detectable by XbaI) were associated with significant effects on LDL-cholesterol (8.3% and 9.3% of sample variance, respectively). The asparagine/serine4311 polymorphism was associated with a significant effect on high density lipoprotein (HDL) cholesterol alone, and there was no significant association with the glutamate/lysine4154 polymorphism (detectable by EcoRI) or the leucine-alanine-leucine (LAL) insertion/deletion polymorphism in the signal peptide. In the patients, polymorphisms creating the three common apo E isoforms were associated with large effects on cholesterol, apo B and triglyceride levels (19.9%, 20.3% and 23.9% of sample variance) of similar magnitude as in the healthy individuals. Apo B polymorphisms were found to be associated with much smaller effects on lipid traits than in the healthy individuals. The only significant association was between the asparagine/serine4311 polymorphism and HDL-triglyceride levels. However, global severity of coronary atherosclerosis at the first angiography was found to be significantly associated with the LAL insertion/deletion polymorphism (P = 0.008). Thus variation at the apo B gene locus is associated with the development of atherosclerosis, but the data suggests that this may act through mechanisms not directly related to effects on measured lipid traits.