Novel Loci for metabolic networks and multi-tissue expression studies reveal genes for atherosclerosis

Association testing of multiple correlated phenotypes offers better power than univariate analysis of single traits. We analyzed 6,600 individuals from two population-based cohorts with both genome-wide SNP data and serum metabolomic profiles. From the observed correlation structure of 130 metabolites measured by nuclear magnetic resonance, we identified 11 metabolic networks and performed a multivariate genome-wide association analysis. We identified 34 genomic loci at genome-wide significance, of which 7 are novel. In comparison to univariate tests, multivariate association analysis identified nearly twice as many significant associations in total. Multi-tissue gene expression studies identified variants in our top loci, SERPINA1 and AQP9, as eQTLs and showed that SERPINA1 and AQP9 expression in human blood was associated with metabolites from their corresponding metabolic networks. Finally, liver expression of AQP9 was associated with atherosclerotic lesion area in mice, and in human arterial tissue both SERPINA1 and AQP9 were shown to be upregulated (6.3-fold and 4.6-fold, respectively) in atherosclerotic plaques. Our study illustrates the power of multi-phenotype GWAS and highlights candidate genes for atherosclerosis.

Alcohol-induced premature permeability in mouse placenta-yolk sac barriers in vivo

OBJECTIVE

Acute alcohol exposure induces malformation and malfunction of placenta-yolk sac tissues in rodents, reducing the labyrinth zone in the placenta and altering the permeability and fluidity of the cell membrane. During normal mouse placentation the cells line up in an optimal way to form a hemotrichorial placenta where layers II and III are connected through gap junctions. These act as molecular sieves that limit the passage of large molecules. PlGF is a developmentally regulated protein that controls the passage of molecules in the vasculosyncytial membranes and media of large blood vessels in the placental villi. In addition to the chorioallontoic placenta, rodents also have another type of placenta that consists of Reichert's membrane within the trophoblast cell layer on the maternal side and the parietal endodermal cells on the embryonic site. This forms a separate materno-fetal transport system. We study here whether alcohol affects these two placental barriers, leading to placental malfunction that in turn diminishes the nutrient supply to the embryo.

STUDY DESIGN

CD-1 mice received two intraperitoneal injections of 3 g/kg ethanol at 4 h intervals at 8.75 days post coitum (dpc). The placentas were collected on 9.5, 11.5 and 14.5 dpc and used for histopathological protein studies. Hemotrichorial cell layer structure interactions through connective tissue and gap junction were analyzed by electron microscopy. The permeability of the feto-maternal barrier was visualized with Evans Blue.

RESULTS

VEGF, a permeability inducer, was found to be up-regulated in the mouse placenta after acute alcohol exposure, and permeability was also affected by altered structures in the barriers that separate the feto-maternal blood circulation which destroyed the gap junctions in the hemotrichorial cell layer, reduced the thickness of Reichert's membrane and interfered with with Reichert's trophoblast/Reichert's parietal interaction. These defects together could have caused the permeability malfunction of the placenta-yolk sac tissues as visualized and quantified here by Evans Blue leakage.

CONCLUSIONS

An altered PlGF/VEGF ratio together with barrier malformation may contribute to placental malfunction by altering the permeability of the feto-maternal barriers. Further studies are needed in order to show whether premature permeability is involved in the intrauterine growth restriction observed in human FAS embryos.

The interplay between lipoprotein phenotypes, adiponectin, and alcohol consumption

CONTEXT AND OBJECTIVE

Lipoproteins are involved in the pathophysiology of several metabolic diseases. Here we focus on the interplay between lipoprotein metabolism and adiponectin with the extension of alcohol intake.

DESIGN AND SUBJECTS

Eighty-three low-to-moderate and 80 heavy alcohol drinkers were studied. Plasma adiponectin, other biochemical and extensive lipoprotein data were measured. Self-organizing maps were applied to characterize lipoprotein phenotypes and their interrelationships with biochemical measures and alcohol consumption.

RESULTS

Alcohol consumption and plasma adiponectin had a strong positive association. Heavy alcohol consumption was associated with decreased low-density lipoprotein cholesterol (LDL-C). Nevertheless, two distinct lipoprotein phenotypes were identified, one with elevated high-density lipoprotein cholesterol (HDL-C) and decreased very-low-density lipoprotein triglycerides (VLDL-TG) together with low prevalence of metabolic syndrome, and the other vice versa. The HDL particles were enlarged in both phenotypes related to the heavy drinkers. The low-to-moderate alcohol drinkers were characterized with high LDL-C and C-enriched LDL particles.

CONCLUSIONS

The analyses per se illustrated the multi-faceted and non-linear nature of lipoprotein metabolism. The heavy alcohol drinkers were characterized either by an anti-atherogenic lipoprotein phenotype (with also the highest adiponectin concentrations) or by a phenotype with pro-atherogenic and metabolic syndrome-like features. Clinically this underlines the need to distinguish the differing individual risk for lipid-related metabolic disturbances also in heavy alcohol drinkers.

Mild cognitive impairment associates with concurrent decreases in serum cholesterol and cholesterol-related lipoprotein subclasses

BACKGROUND AND OBJECTIVE

Accumulating evidence suggests that serum lipids are associated with cognitive decline and dementias. However, majority of the existing information concerns only serum total cholesterol (TC) and data at the level of lipoprotein fractions and subclasses is limited. The aim of this study was to explore the levels and trends of main cholesterol and triglyceride measures and eight lipoprotein subclasses during normal aging and the development of mild cognitive impairment by following a group of elderly for six years.

DESIGN

Longitudinal.

SETTING

City of Kuopio, Finland.

PARTICIPANTS

45 elderly individuals of which 20 developed mild cognitive impairment (MCI) during the follow-up.

MEASUREMENTS

On each visit participants underwent an extensive neuropsychological and clinical assessment. Lipoprotein levels were measured via 1H NMR from native serum samples.

RESULTS

Serum cholesterol and many primarily cholesterol-associated lipoprotein measures clearly decreased in MCI while the trends were increasing for those elderly people who maintained normal cognition.

CONCLUSION

These findings suggest that a decreasing trend in serum cholesterol measures in elderly individuals may suffice as an indication for more detailed inspection for potential signs of cognitive decline.

Metabolic signatures of insulin resistance in 7,098 young adults

Metabolite associations with insulin resistance were studied in 7,098 young Finns (age 31 ± 3 years; 52% women) to elucidate underlying metabolic pathways. Insulin resistance was assessed by the homeostasis model (HOMA-IR) and circulating metabolites quantified by high-throughput nuclear magnetic resonance spectroscopy in two population-based cohorts. Associations were analyzed using regression models adjusted for age, waist, and standard lipids. Branched-chain and aromatic amino acids, gluconeogenesis intermediates, ketone bodies, and fatty acid composition and saturation were associated with HOMA-IR (P < 0.0005 for 20 metabolite measures). Leu, Ile, Val, and Tyr displayed sex- and obesity-dependent interactions, with associations being significant for women only if they were abdominally obese. Origins of fasting metabolite levels were studied with dietary and physical activity data. Here, protein energy intake was associated with Val, Phe, Tyr, and Gln but not insulin resistance index. We further tested if 12 genetic variants regulating the metabolites also contributed to insulin resistance. The genetic determinants of metabolite levels were not associated with HOMA-IR, with the exception of a variant in GCKR associated with 12 metabolites, including amino acids (P < 0.0005). Nonetheless, metabolic signatures extending beyond obesity and lipid abnormalities reflected the degree of insulin resistance evidenced in young, normoglycemic adults with sex-specific fingerprints.

High-throughput quantification of circulating metabolites improves prediction of subclinical atherosclerosis

AIMS

High-throughput metabolite quantification holds promise for cardiovascular risk assessment. Here, we evaluated whether metabolite quantification by nuclear magnetic resonance (NMR) improves prediction of subclinical atherosclerosis in comparison to conventional lipid testing.

METHODS AND RESULTS

Circulating lipids, lipoprotein subclasses, and small molecules were assayed by NMR for 1595 individuals aged 24-39 years from the population-based Cardiovascular Risk in Young Finns Study. Carotid intima-media thickness (IMT), a marker of subclinical atherosclerosis, was measured in 2001 and 2007. Baseline conventional risk factors and systemic metabolites were used to predict 6-year incidence of high IMT (≥ 90 th percentile) or plaque. The best prediction of high intima-media thickness was achieved when total and HDL cholesterol were replaced by NMR-determined LDL cholesterol and medium HDL, docosahexaenoic acid, and tyrosine in prediction models with risk factors from the Framingham risk score. The extended prediction model improved risk stratification beyond established risk factors alone; area under the receiver operating characteristic curve 0.764 vs. 0.737, P =0.02, and net reclassification index 17.6%, P =0.0008. Higher docosahexaenoic acid levels were associated with decreased risk for incident high IMT (odds ratio: 0.74; 95% confidence interval: 0.67-0.98; P = 0.007). Tyrosine (1.33; 1.10-1.60; P = 0.003) and glutamine (1.38; 1.13-1.68; P = 0.001) levels were associated with 6-year incident high IMT independent of lipid measures. Furthermore, these amino acids were cross-sectionally associated with carotid IMT and the presence of angiographically ascertained coronary artery disease in independent populations.

CONCLUSION

High-throughput metabolite quantification, with new systemic biomarkers, improved risk stratification for subclinical atherosclerosis in comparison to conventional lipids and could potentially be useful for early cardiovascular risk assessment.

Effect of repeated dietary counseling on serum lipoproteins from infancy to adulthood

BACKGROUND AND OBJECTIVE

As atherosclerosis is a lifelong process, prevention of exposure to its risk factors should start at an early age. Our aim was to study the influences of repeated low saturated fat dietary counseling on dietary intakes and lipoprotein measures from infancy to adulthood.

METHODS

Dietary intakes (food records) and serum lipid profile were studied annually from 7 months to 19 years of age in an atherosclerosis prevention study (Special Turku Coronary Risk Factor Intervention Project), comprising 540 children in the intervention group and 522 children in the control group. Serum total and high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) were measured and used to estimate very low-density lipoprotein-TG, intermediate-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and HDL(2)-C, as well as apolipoproteins A-1 and B.

RESULTS

Compared with controls, the intervention children had a lower saturated fat intake (mean daily difference [95% confidence interval] between groups: -2.1 [-2.3, -1.9] percentage of total energy intake in boys; -1.9 [-2.1, -1.7] percentage of total energy intake in girls, both P < .001) and LDL-C concentration (difference [95% confidence interval] between groups: -0.18 [-0.26, -0.10] mmol/L, P < .001 in boys; -0.10 [-0.19, -0.01] mmol/L, P = .037 in girls), whereas HDL-C and apolipoprotein A-1 did not differ between the study groups. In boys, total cholesterol and intermediate-density lipoprotein cholesterol, very low-density lipoprotein-TG, apolipoprotein B, and TG concentrations were also lower in the intervention than in the control group, whereas no differences were found in girls.

CONCLUSIONS

Repeated dietary counseling is effective in decreasing saturated fat intake and serum LDL-C values from infancy until 19 years of age in both genders. In boys, significant intervention effects are evident in various lipoprotein measures, indicating a more favorable lipid profile in the counseling group.

Full-length visfatin levels are associated with inflammation in women with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common gynaecological endocrinopathy characterized by oligomenorrhea, amenorrhoea, clinical and/or biochemical hyperandrogenism and polycystic ovaries. Abdominal deposition of excess body fat and metabolic diseases like insulin resistance and compensatory hyperinsulinemia are commonly observed in PCOS subjects. It has been suggested that visfatin is an adipokine secreted from the abdominal fat influencing glucose metabolism and might therefore contribute to the metabolic disturbances in PCOS.

MATERIALS AND METHODS

We measured circulating full-length visfatin levels with a specific enzyme immunoassay (AdipoGen Inc, Incheon, South-Korea) in 57 women with self-reported symptoms of PCOS (hirsutism and/or oligomenorrhea) and ultrasound confirmed polycystic ovaries, and in 57 controls from the Northern Finland 1966 Birth Cohort and explored its association with metabolic and inflammatory parameters.

RESULTS

Polycystic ovary syndrome cases had higher body mass index (BMI) (25·7 vs. 24·1 kg/m(2)) and waist circumference (83·2 vs. 78·8 cm) compared to controls, yet there was no difference in plasma visfatin levels between them. In contrast, visfatin significantly correlated with C-reactive protein (CRP) in the control group and with white blood cell count (WBC) in both groups. In linear regression analysis, adjusted for PCOS, smoking, socioeconomic status, BMI or waist circumference, serum lipids and markers of glucose metabolism and hormone status, only WBC remained significantly associated with plasma visfatin levels.

CONCLUSION

Our results suggest that circulating visfatin levels correlate with WBC and CRP but are not associated with PCOS, obesity or metabolic markers, suggesting that visfatin may act as a proinflammatory cytokine.

Genome-wide association study identifies multiple loci influencing human serum metabolite levels

Nuclear magnetic resonance assays allow for measurement of a wide range of metabolic phenotypes. We report here the results of a GWAS on 8,330 Finnish individuals genotyped and imputed at 7.7 million SNPs for a range of 216 serum metabolic phenotypes assessed by NMR of serum samples. We identified significant associations (P < 2.31 × 10(-10)) at 31 loci, including 11 for which there have not been previous reports of associations to a metabolic trait or disorder. Analyses of Finnish twin pairs suggested that the metabolic measures reported here show higher heritability than comparable conventional metabolic phenotypes. In accordance with our expectations, SNPs at the 31 loci associated with individual metabolites account for a greater proportion of the genetic component of trait variance (up to 40%) than is typically observed for conventional serum metabolic phenotypes. The identification of such associations may provide substantial insight into cardiometabolic disorders.

Genome-wide association study identifies loci influencing concentrations of liver enzymes in plasma

Concentrations of liver enzymes in plasma are widely used as indicators of liver disease. We carried out a genome-wide association study in 61,089 individuals, identifying 42 loci associated with concentrations of liver enzymes in plasma, of which 32 are new associations (P = 10(-8) to P = 10(-190)). We used functional genomic approaches including metabonomic profiling and gene expression analyses to identify probable candidate genes at these regions. We identified 69 candidate genes, including genes involved in biliary transport (ATP8B1 and ABCB11), glucose, carbohydrate and lipid metabolism (FADS1, FADS2, GCKR, JMJD1C, HNF1A, MLXIPL, PNPLA3, PPP1R3B, SLC2A2 and TRIB1), glycoprotein biosynthesis and cell surface glycobiology (ABO, ASGR1, FUT2, GPLD1 and ST3GAL4), inflammation and immunity (CD276, CDH6, GCKR, HNF1A, HPR, ITGA1, RORA and STAT4) and glutathione metabolism (GSTT1, GSTT2 and GGT), as well as several genes of uncertain or unknown function (including ABHD12, EFHD1, EFNA1, EPHA2, MICAL3 and ZNF827). Our results provide new insight into genetic mechanisms and pathways influencing markers of liver function.

Quitting a weight loss program is associated with anhedonia: preliminary findings of the Lifestyle Intervention Treatment Evaluation Study in northern Finland

OBJECTIVES

To examine whether a diagnosis for major depression, chronic depression or specific symptoms of depression is associated with the risk of quitting a weight loss program.

STUDY DESIGN

The study involved 82 overweight adults participating in the Lifestyle Intervention Treatment Evaluation (LITE) follow-up study at Oulu University Hospital in northern Finland.

METHODS

Psychiatric diagnostic assessments were based on the Structured Clinical Interview for DSMIV disorders (SCID-I) conducted by a clinical psychiatrist. Anhedonia (lack of pleasure) was assessed as one of the core symptoms of major depression and chronic depression (dysthymia). Anhedonia was defined to be present if the participants reported having suffered a major loss of interest during the previous month.

RESULTS

Twenty participants (24.4%) quit during the 6-month intervention period. Anhedonia put individuals at risk of quitting the weight loss program (bivariate analysis OR 3.1, 95% CI 0.8-11.6, p=0.091, multivariate analysis OR 6.5, 95% CI 1.1-38.2, p=0.038). However, a diagnosis for major depression or chronic depression did not predict quitting.

CONCLUSIONS

Individual assessments of obesity and overweight should also include an assessment for subthreshold depression, mainly anhedonia.

Effects of low-dose liquorice alone or in combination with hydrochlorothiazide on the plasma potassium in healthy volunteers

Both liquorice and thiazide diuretics have hypokalaemic effects. In spite of their prevalent use, there are no studies on hypokalaemia caused by the combination of liquorice and thiazides. We recruited 10 healthy volunteers in order to study the effects of 32 g liquorice alone or in combination with 25mg hydrochlorothiazide a day for 2 weeks. The trial had a randomized, open and crossover design. During the liquorice phase, there were no changes in plasma potassium, sodium, creatinine, renin activity, serum aldosterone, blood pressure or heart rate. Weight tended to increase by 0.4 kg (70.2 to 70.6 kg; p=0.056). During the liquorice-hydrochlorothiazide phase, the plasma potassium decreased by 0.32 mmol/l (p=0.0015), plasma renin activity increased by 1.6 microg/l/h (p=0.0064) and the weight decreased by 0.9 kg (70.5 to 69.6 kg, p=0.0065). Twenty per cent of the subjects (2/10) became hypokalaemic during the combined liquorice-hydrochlorothiazide treatment. Furthermore, both subjects developed hypokalaemia within the first week of the combined treatment leading to premature discontinuation. The evaluation of liquorice consumption habits is warranted when initiating thiazide medications to avoid the excessive risk of hypokalaemia associated with the combined use of low-dose liquorice and thiazide diuretics.

Characterization of systemic metabolic phenotypes associated with subclinical atherosclerosis

Detailed molecular phenotyping gives insight into disease mechanisms and can individualize medical practice for improved risk assessment and treatment. We show in an epidemiological study (n = 4309) that the multi-metabolic profiles obtained by serum NMR metabonomics inherently associate with the extent of atherosclerosis already in preclinical stages. Data-driven analysis of the spectral profiles of healthy, young adults revealed three distinct metabolic phenotypes associated with high carotid intima-media thickness (IMT), a surrogate marker of cardiovascular disease. The phenotypes were characterized by varying combinations of well-known metabolic disturbances like elevated VLDL and LDL and low HDL levels. Low IMT was also associated with distinct metabolic phenotypes with lipoprotein as well as other biochemical characteristics partly opposing those found for the high IMT phenotypes. Profiles of low-molecular-weight metabolites quantified from the experimentation were also characteristic for the metabolic phenotypes and substantiate developments toward the use of multi-metabolic risk phenotypes. The methodology can be taken as a direct extension for the routine analytics used for the risk assessment of atherosclerosis; quantification of metabolites will complement and might even replace conventional lipid measurements. Serum NMR metabonomics is therefore anticipated as a rational option for comprehensive cardiovascular risk assessment.

The prevalence and predictive value of individual criteria for metabolic syndrome in schizophrenia: a Northern Finland 1966 Birth Cohort Study

The metabolic syndrome (MetS) is associated with elevated risk of diabetes and cardiovascular morbidity. However, little is known of the sensitivity, specificity and predictive value of individual criteria in patients with schizophrenia. We studied the prevalence of MetS using the International Diabetes Federation (IDF) and adapted National Cholesterol Education Program (NCEP-ATPIII) criteria in the Northern Finland 1966 Birth Cohort population. In addition, the sensitivity, specificity and predictive values for individual criteria were determined. Both adapted NCEP-ATPIII and IDF criteria for MetS identified the same cases (29% of all schizophrenia patients). Among the IDF criteria, hypertriglyceridemia had the highest sensitivity, correctly identifying 77.8% of the patients. Reduced HDL cholesterol was the most specific criteria, with 95% specificity equalling a positive likelihood ratio of 9.78. Thus both the IDF and NCEP-ATPIII criteria may be equally useful in identifying MetS.

Separating the mechanism-based and off-target actions of cholesteryl ester transfer protein inhibitors with CETP gene polymorphisms

BACKGROUND

Cholesteryl ester transfer protein (CETP) inhibitors raise high-density lipoprotein (HDL) cholesterol, but torcetrapib, the first-in-class inhibitor tested in a large outcome trial, caused an unexpected blood pressure elevation and increased cardiovascular events. Whether the hypertensive effect resulted from CETP inhibition or an off-target action of torcetrapib has been debated. We hypothesized that common single-nucleotide polymorphisms in the CETP gene could help distinguish mechanism-based from off-target actions of CETP inhibitors to inform on the validity of CETP as a therapeutic target.

METHODS AND RESULTS

We compared the effect of CETP single-nucleotide polymorphisms and torcetrapib treatment on lipid fractions, blood pressure, and electrolytes in up to 67 687 individuals from genetic studies and 17 911 from randomized trials. CETP single-nucleotide polymorphisms and torcetrapib treatment reduced CETP activity and had a directionally concordant effect on 8 lipid and lipoprotein traits (total, low-density lipoprotein, and HDL cholesterol; HDL2; HDL3; apolipoproteins A-I and B; and triglycerides), with the genetic effect on HDL cholesterol (0.13 mmol/L, 95% confidence interval [CI] 0.11 to 0.14 mmol/L) being consistent with that expected of a 10-mg dose of torcetrapib (0.13 mmol/L, 95% CI 0.10 to 0.15). In trials, 60 mg of torcetrapib elevated systolic and diastolic blood pressure by 4.47 mm Hg (95% CI 4.10 to 4.84 mm Hg) and 2.08 mm Hg (95% CI 1.84 to 2.31 mm Hg), respectively. However, the effect of CETP single-nucleotide polymorphisms on systolic blood pressure (0.16 mm Hg, 95% CI -0.28 to 0.60 mm Hg) and diastolic blood pressure (-0.04 mm Hg, 95% CI -0.36 to 0.28 mm Hg) was null and significantly different from that expected of 10 mg of torcetrapib.

CONCLUSIONS

Discordance in the effects of CETP single-nucleotide polymorphisms and torcetrapib treatment on blood pressure despite the concordant effects on lipids indicates the hypertensive action of torcetrapib is unlikely to be due to CETP inhibition or shared by chemically dissimilar CETP inhibitors. Genetic studies could find a place in drug-development programs as a new source of randomized evidence for drug-target validation in humans.

Vascular endothelial growth factor gene variation and the response to photodynamic therapy in age-related macular degeneration

PURPOSE

To evaluate the role of vascular endothelial growth factor (VEGF) gene polymorphisms in exudative age-related macular degeneration (AMD).

DESIGN

Retrospective, comparative case series.

PARTICIPANTS

Patients with recent exudative AMD (n = 162) and age-matched subjects without AMD (n = 85).

METHODS

Fluorescein angiography (FA), clinical examination, and single nucleotide polymorphism (SNP) genotyping.

MAIN OUTCOME MEASURES

The frequencies of 3 VEGF gene SNPs were analyzed, 1 at the promoter site (rs699947, A-->C) and 2 intronic SNPs (rs2146323, A-->C, and rs3025033, A-->G), in relation to the risk of AMD, to choroidal neovascular (CNV) lesion size and configuration, and to the anatomic response to photodynamic therapy (PDT). These SNPs were chosen to cover all the haploblocks of the VEGF gene. The 86 patients who had undergone PDT were classified as either PDT responders or PDT nonresponders based on the outcome of PDT after the last treatment session. For the PDT responders, the treating physician had deemed the lesion to be clinically dry and without leakage from CNV in FA at a visit scheduled at least 12 weeks after the last PDT treatment. For the PDT nonresponders, the PDT sessions had been discontinued by the treating retina specialist because of an apparently poor response and a still exudative lesion after several PDT sessions.

RESULTS

The presence of exudative AMD or lesion size or configuration was not associated with the SNPs studied here. The frequencies of the rs699947 were significantly different in PDT nonresponders and PDT responders. The AA, AC, and CC genotypes were 14%, 39%, and 46%, respectively, in PDT nonresponders, compared with 40%, 48%, and 12%, respectively, in the PDT responders (P = 0.0008). The corresponding frequencies for the rs2146323 AA, AC, and CC genotypes were 4%, 32%, and 64%, respectively, in nonresponders and 24%, 38%, and 38%, respectively, in responders (P = 0.0369). The genotypes of the rs3025033 SNP were distributed evenly between the responders and nonresponders.

CONCLUSIONS

The VEGF gene polymorphic SNPs at rs699947 and rs2146323 are strong determinants of the anatomic outcome after PDT, but the SNPs studied were not associated with the presence of exudative AMD or with the CNV lesion size or configuration.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Characterization of metabolic interrelationships and in silico phenotyping of lipoprotein particles using self-organizing maps

Plasma lipid concentrations cannot properly account for the complex interactions prevailing in lipoprotein (patho)physiology. Sequential ultracentrifugation (UCF) is the gold standard for physical lipoprotein isolations allowing for subsequent analyses of the molecular composition of the particles. Due to labor and cost issues, however, the UCF-based isolations are usually done only for VLDL, LDL, and HDL fractions; sometimes with the addition of intermediate density lipoprotein (IDL) particles and the fractionation of HDL into HDL(2) and HDL(3) (as done here; n = 302). We demonstrate via these data, with the lipoprotein lipid concentration and composition information combined, that the self-organizing map (SOM) analysis reveals a novel data-driven in silico phenotyping of lipoprotein metabolism beyond the experimentally available classifications. The SOM-based findings are biologically consistent with several well-known metabolic characteristics and also explain some apparent contradictions. The novelty is the inherent emergence of complex lipoprotein associations; e.g., the metabolic subgrouping of the associations between plasma LDL cholesterol concentrations and the structural subtypes of LDL particles. Importantly, lipoprotein concentrations cannot pinpoint lipoprotein phenotypes. It would generally be beneficial to computationally enhance the UCF-based lipoprotein data as illustrated here. Particularly, the compositional variations within the lipoprotein particles appear to be a fundamental issue with metabolic and clinical corollaries.

The effect of eating behavior on weight loss and maintenance during a lifestyle intervention

OBJECTIVE

To investigate the effects of intensive counseling on eating behavior and weight loss and maintenance and their associations.

METHODS

A randomized weight loss counseling intervention with follow-up of 18 months, conducted between 2002-2004 at Oulu University Hospital, Finland included obese adults (n=82, body mass index >27 kg/m(2)). Subjects were randomized into 1) intensive counseling and 2) short-term counseling. Forty-nine subjects who completed the study were included. Eating behavior was repeatedly assessed by the Three Factor Eating Questionnaire-18 and Binge Eating Scale.

RESULTS

Eating behavior improved in both groups. Effect of counseling was -5.0+/-5.7 kg compared with -2.4+/-2.5 kg in the control group (p<0.05 between the groups) during the first 6 months. At 18 months the weight loss results were -2.6+/-6 kg and -0.7+/-3.5 kg, respectively (NS). Success in weight loss maintenance is associated with improved eating behavior (p<0.05). By contrast, failure in weight loss is associated with high scores of uncontrolled eating and binge eating symptoms at the baseline (p<0.05).

CONCLUSIONS

Both intensive and short-term interventions improved eating behavior and weight loss but there was no difference between the two modes of intervention. The association between the improvement of eating behaviour and the success of weight loss suggests a causal relationship which however should be confirmed in a prospective study focusing specifically on this aspect.

High-throughput serum NMR metabonomics for cost-effective holistic studies on systemic metabolism

A high-throughput proton (1H) nuclear magnetic resonance (NMR) metabonomics approach is introduced to characterise systemic metabolic phenotypes. The methodology combines two molecular windows that contain the majority of the metabolic information available by 1H NMR from native serum, e.g. serum lipids, lipoprotein subclasses as well as various low-molecular-weight metabolites. The experimentation is robotics-controlled and fully automated with a capacity of about 150-180 samples in 24 h. To the best of our knowledge, the presented set-up is unique in the sense of experimental high-throughput, cost-effectiveness, and automated multi-metabolic data analyses. As an example, we demonstrate that the NMR data as such reveal associations between systemic metabolic phenotypes and the metabolic syndrome (n = 4407). The high-throughput of up to 50,000 serum samples per year is also paving the way for this technology in large-scale clinical and epidemiological studies. In contradiction to single 'biomarkers', the application of this holistic NMR approach and the integrated computational methods provides a data-driven systems biology approach to biomedical research.

Polymorphism of the manganese superoxide dismutase gene but not of vascular endothelial growth factor gene is a risk factor for diabetic retinopathy

BACKGROUND

In diabetic retinopathy, the vascular endothelium is damaged due to oxidative stress and inflammation, and vitreous VEGF concentration becomes elevated. The association of diabetic retinopathy with single nucleotide polymorphisms (SNPs) was studied on two genes: VEGF, an important mediator of neovascularisation, and MnSOD, a major antioxidant enzyme.

METHODS

The study population was 755 individuals consisting of 131 diabetic (type 1 or type 2) patients with diabetic retinopathy (DR group), 98 diabetic controls without retinopathy (DC group) and 526 non-diabetic controls. VEGF SNPs rs699947, rs2010963, rs2146232, rs3025033, rs3025039 and Ala16Val polymorphism of the MnSOD gene were genotyped.

RESULTS

The frequencies of allele and genotype of the single genotyped VEGF SNPs or reconstructed haplotypes of these single SNPs did not differ between DR and DC groups. A higher frequency of the AlaAla genotype (p = 0.03) and Ala16 allele (p = 0.04) of the MnSOD gene in the DR group was found when compared with the DC group.

CONCLUSIONS

In conclusion, the studied VEGF SNPs were not associated with the risk of diabetic retinopathy, and so it is unlikely that the VEGF gene is a major locus determining the risk of diabetic retinopathy. A statistically significant association of MnSOD Ala16Val polymorphism with diabetic retinopathy was found.

The –1C to T polymorphism in the annexin A5 gene is not associated with the risk of acute myocardial infarction or sudden cardiac death in middle‐aged Finnish males

OBJECTIVE

A common polymorphism (-1C to T) in the translation initiation sequence of annexin A5 (ANV) gene has recently been associated with a decreased risk of acute myocardial infarction (AMI). The aim of the present study was to analyze the association between the ANV genepolymorphism and the risk of AMI and ischemic sudden cardiac death (SCD) in middle-aged Finnish males.

MATERIAL AND METHODS

A case-control study involving three distinct groups of subjects was carried out: (1) victims of SCD (n=98), (2) survivors of AMI (n=212), and (3) randomly selected control subjects without any history of coronary heart disease (n=243). The ANV polymorphism was genotyped in each study group.

RESULTS

Among the control group of healthy Finnish males the prevalence rates of the CC, CT, and TT genotypes were 83.1%, 15.2%, and 1.6%, respectively. Among the survivors of AMI, the prevalence rates of CC, CT, and TT were 79.7%, 20.3%, and 0%, respectively, and among the victims of SCD 83.7%, 16.3%, and 0%, respectively. No significant differences in the genotype or allele distributions were observed between the study groups.

CONCLUSION

The -1C to T polymorphism in the ANV gene is not associated with the risk of AMI or SCD in middle-aged Finnish males.

Variation in the vascular endothelial growth factor gene, carotid intima-media thickness and the risk of acute myocardial infarction

BACKGROUND

Vascular endothelial growth factor (VEGF) is a potent angiogenic growth factor, but its role in atherogenesis is still unclear. Our goal was to study whether three variants of the VEGF gene, previously associated with VEGF production, are linked to atherosclerosis defined as carotid intima-media thickness (IMT) and as the risk of acute myocardial infarction (AMI).

MATERIAL AND METHODS

Three VEGF gene single nucleotide polymorphisms (SNPs) (-2578A>C rs699947, -634C>G rs2010963 and +936C>T rs3025039) were genotyped in 516 control subjects of the OPERA (Oulu Project Elucidating Risk of Atherosclerosis) cohort and in 251 survivors of AMI. In the OPERA cohort, the genotyped SNPs were analysed for their association with IMT. The SNPs were also analysed for their association with the risk of AMI, a complication of advanced atherosclerosis. In addition, haplotype frequencies and their associated effects on IMT and on the risk of AMI were estimated.

RESULTS

None of the single genotyped polymorphisms was significantly associated with overall IMT or with the risk of AMI. However, the haplotype CCC was associated with higher overall IMT without plaques in women (p = 0.01, haplotypic effect +0.03 mm), the haplotype CCT with higher IMT without plaques in the internal carotid artery in men (p = 0.001, +0.11), while the haplotype AGT was associated with reduced AMI risk (p = 0.015, OR = 0.46).

CONCLUSIONS

Variation in the VEGF gene is weakly associated with IMT and the risk of AMI, but the effect can only be observed when the information of the SNPs is combined by constructing haplotypes.

Plasma HDL cholesterol and blood glucose in non-insulin-dependent diabetics related to liver lipids and microsomal enzyme activity

The major lipid predictors of coronary events, plasma high density lipoprotein cholesterol (HDL-C) and the HDL-C/total cholesterol (T-C) ratio, and blood glucose (BG) in 12 subjects with non-insulin-dependent diabetes mellitus were related to hepatic lipids, proteins and microsomal enzyme activity assessed by liver cytochrome P-450 (P-450). Non-insulin-dependent diabetics had low HDL-C/T-C ratio, liver phospholipid (PL) and P-450 and high serum and liver triglyceride (TG) concentrations. Plasma HDL-C was decreased, and BG high, especially in subjects with reduced PL and P-450. The HDL-C/T-C ratio was directly proportional to liver PL and P-450 and unrelated to hepatic TG. Increases in liver PL and microsomal enzyme activity may be favorably reflected both in cholesterol distribution and diabetic control.

Plasma high-density lipoproteins and liver lipids and proteins in man. Relation to hepatic histology and microsomal enzyme induction

The association of high-density lipoproteins (HDL) in plasma with liver lipids and proteins was investigated in 28 subjects with diagnostic liver biopsy. Lipids and proteins were evaluated in relation to hepatic histology and microsomal enzyme induction, assessed by liver cytochrome P-450. Moderate-severe hepatic parenchymal changes were associated with low liver phospholipids, protein and cytochrome P-450, low plasma HDL cholesterol (HDL-C), and high hepatic triglycerides. Liver microsomal induction accompanying anticonvulsant therapy was associated with high liver phospholipids and protein, high plasma HDL-C, apoproteins A-I and A-II, and high HDL-C/total cholesterol (T-C) ratio. HDL-C, A-I and the HDL-C/T-C ratio were directly proportional to liver phospholipids, protein and cytochrome P-450, inversely related to hepatic triglycerides. Increases in hepatic phospholipids and protein, characteristic of microsomal induction, may lead to the elevation of plasma HDL apoprotein and HDL-C levels and HDL-C/T-C ratios, and thus reduce the risk of coronary heart disease.

Estimation of VLDL, IDL, LDL, HDL2, apoA-I, and apoB from the Friedewald inputs--apoB and IDL, but not LDL, are associated with mortality in type 1 diabetes

BACKGROUND

There is an unmet need for a straightforward and cost-effective assessment of multiple lipoprotein risk factors for vascular diseases.

AIMS

1) To study the relation of various lipoprotein lipid and apolipoprotein (apo) measures on the Friedewald inputs, i.e. plasma triglycerides (TG), cholesterol (TC), and high-density lipoprotein cholesterol (HDL-C). 2) To build up regression models for the appropriate measures based solely on the Friedewald inputs.

METHODS

Data were available for 1,775 plasma samples, from which very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL), and HDL were also isolated by ultracentrifugation. For HDL(2)-C and apolipoproteins, 343 and 247 samples were available, respectively.

RESULTS

Accurate models were obtained for VLDL-TG (cross-validation r=0.98), LDL-C (r=0.91), HDL(2)-C (r=0.92), apoA-I (r=0.92), and apoB (r=0.95). A semi-quantitative model was obtained for IDL-C (r=0.78). Due to the anticipated role of IDL-C in atherosclerosis, it was still kept within the accepted models and pursued further. The associations of the estimates with premature deaths were studied in 4,084 patients with type 1 diabetes. The associations of IDL-C and LDL-C were markedly different, the best predictors of mortality being apoB, apoB to apoA-I ratio, and IDL-C.

CONCLUSIONS

The new models allow identification of clinically relevant lipoprotein profiles with no added cost to the conventional Friedewald formula.

High vitreous concentration of vascular endothelial growth factor in diabetic patients with proliferative retinopathy using statins

BACKGROUND

Vascular endothelial growth factor (VEGF) plays an important role in the development of diabetic retinopathy. Previous studies have suggested that angiotensin-converting enzyme (ACE) inhibitor therapy may reduce vitreous VEGF concentration in diabetic retinopathy. Also HMG CoA reductase inhibitors (statins), known for their beneficial effects on vascular endothelium, might influence vitreous VEGF concentration in diabetic retinopathy.

AIM

Vitreous VEGF concentration of diabetic patients with proliferative retinopathy using statin therapy and/or ACE inhibitor therapy was studied.

METHODS

Fifty diabetic patients with proliferative diabetic retinopathy, 21 diabetic control patients without proliferative retinopathy, and 43 non-diabetic control subjects underwent vitrectomy. Vitreous samples were collected at the beginning of surgery, and VEGF concentration was assessed using a chemiluminescent VEGF immunoassay.

RESULTS

Vitreous VEGF concentration was significantly higher in diabetic patients with proliferative retinopathy using statins than in those not using statins. The diabetic patients with proliferative retinopathy were divided into subgroups according to use of ACE inhibitor and/or statin medication. These groups did not differ significantly in concentration of vitreous VEGF.

CONCLUSIONS

Statin therapy is associated with high vitreous VEGF concentration in diabetic patients with proliferative retinopathy. In contrast to previous reports, ACE inhibitor use did not significantly influence vitreous VEGF concentration in these patients.

1H NMR metabonomics of plasma lipoprotein subclasses: elucidation of metabolic clustering by self-organising maps

(1)H NMR spectra of plasma are known to provide specific information on lipoprotein subclasses in the form of complex overlapping resonances. A combination of (1)H NMR and self-organising map (SOM) analysis was applied to investigate if automated characterisation of subclass-related metabolic interactions can be achieved. To reliably assess the intrinsic capability of (1)H NMR for resolving lipoprotein subclass profiles, sum spectra representing the pure lipoprotein subclass part of actual plasma were simulated with the aid of experimentally derived model signals for 11 distinct lipoprotein subclasses. Two biochemically characteristic categories of spectra, representing normolipidaemic and metabolic syndrome status, were generated with corresponding lipoprotein subclass profiles. A set of spectra representing a metabolic pathway between the two categories was also generated. The SOM analysis, based solely on the aliphatic resonances of these simulated spectra, clearly revealed the lipoprotein subclass profiles and their changes. Comparable SOM analysis in a group of 69 experimental (1)H NMR spectra of serum samples, which according to biochemical analyses represented a wide range of lipoprotein lipid concentrations, corroborated the findings based on the simulated data. Interestingly, the choline-N(CH(3))(3) region seems to provide more resolved clustering of lipoprotein subclasses in the SOM analyses than the methyl-CH(3) region commonly used for subclass quantification. The results illustrate the inherent suitability of (1)H NMR metabonomics for automated studies of lipoprotein subclass-related metabolism and demonstrate the power of SOM analysis in an extensive and representative case of (1)H NMR metabonomics.

A novel Bayesian approach to quantify clinical variables and to determine their spectroscopic counterparts in 1H NMR metabonomic data

BACKGROUND

A key challenge in metabonomics is to uncover quantitative associations between multidimensional spectroscopic data and biochemical measures used for disease risk assessment and diagnostics. Here we focus on clinically relevant estimation of lipoprotein lipids by 1H NMR spectroscopy of serum.

RESULTS

A Bayesian methodology, with a biochemical motivation, is presented for a real 1H NMR metabonomics data set of 75 serum samples. Lipoprotein lipid concentrations were independently obtained for these samples via ultracentrifugation and specific biochemical assays. The Bayesian models were constructed by Markov chain Monte Carlo (MCMC) and they showed remarkably good quantitative performance, the predictive R-values being 0.985 for the very low density lipoprotein triglycerides (VLDL-TG), 0.787 for the intermediate, 0.943 for the low, and 0.933 for the high density lipoprotein cholesterol (IDL-C, LDL-C and HDL-C, respectively). The modelling produced a kernel-based reformulation of the data, the parameters of which coincided with the well-known biochemical characteristics of the 1H NMR spectra; particularly for VLDL-TG and HDL-C the Bayesian methodology was able to clearly identify the most characteristic resonances within the heavily overlapping information in the spectra. For IDL-C and LDL-C the resulting model kernels were more complex than those for VLDL-TG and HDL-C, probably reflecting the severe overlap of the IDL and LDL resonances in the 1H NMR spectra.

CONCLUSION

The systematic use of Bayesian MCMC analysis is computationally demanding. Nevertheless, the combination of high-quality quantification and the biochemical rationale of the resulting models is expected to be useful in the field of metabonomics.

Effects of phosphatidylethanol on mouse adipocyte differentiation and expression of stearoyl-CoA desaturase 1

BACKGROUND

Phosphatidylethanol (PEth) is an aberrant phospholipid formed in vivo only in the presence of ethanol. In circulation PEth is associated with lipoproteins and is transferred from one lipoprotein to another. Lipoprotein-associated PEth affects endothelial and smooth muscle cells of blood vessels, but its effects on other cell types have not been explored. Adipocytes have a central role in metabolic syndrome and obesity. In this study we tested whether lipoprotein-associated PEth affects stearoyl-CoA desaturase 1 (SCD1) which plays a major role in lipid-mediated signaling in the differentiation of adipocytes.

METHODS

Mouse 3T3-L1 preadipocytes were differentiated to adipocytes in the presence of high-density lipoproteins (HDL) isolated from the plasma of healthy volunteers or PEth-containing HDL modified in vitro. After incubation, fat accumulation, SCD1 mRNA expression, SCD1 protein content, and fatty acid composition of adipocytes were determined.

RESULTS

Phosphatidylethanol-containing HDL particles inhibited adipocyte differentiation and decreased the 18:1/18:0 ratio of cellular fatty acids by 28% compared with native HDL particles. Moreover, PEth-containing HDL reduced the SCD1 protein content by 39%.

CONCLUSIONS

Lipoprotein-associated PEth may mediate the effects of ethanol on SCD1 and differentiation of preadipocytes to adipocytes.

Biochemical markers of alcoholism

Alcohol and alcohol-related diseases have become a major cause of death in Western countries. The most sensitive and specific of the commonly used biomarkers of alcohol intake are carbohydrate-deficient transferrin (CDT), and the combination of gamma-glutamyltransferase (GGT) and CDT. Other widely used laboratory markers are GGT, mean corpuscular volume of erythrocytes and the ratio of aspartate aminotransferase to alanine aminotransferase. Blood ethanol levels reveal recent alcohol use. However, more specific and sensitive biomarkers to improve the detection of excessive alcohol use at an early stage are needed. New biomarkers, not yet used in routine clinical work, include phosphatidylethanol, fatty acid ethyl esters, ethyl glucuronide, sialic acid, and acetaldehyde adducts.

An association between manganese superoxide dismutase polymorphism and outcome of chemotherapy in acute myeloid leukemia

Manganese superoxide dismutase (MnSOD) protects cells against oxidative stress by eliminating superoxides. Hypothetically, decreased MnSOD levels in cancer might lead to increased oxidative stress and, thus, to increased sensitivity of cells to chemotherapy agents. Eighty-nine patients with acute myeloid leukemia (AML) were analyzed for a functional C to T polymorphism of MnSOD, which could potentially lead to decreased enzyme concentrations inside mitochondria. A significant survival advantage (p=0.02) was observed for those AML patients carrying T-containing alleles of MnSOD compared to the patients with the CC genotype. These preliminary results may indicate an important role for genetic factors regulating the cellular redox state in determining the outcome of leukemia chemotherapy.

Effects of ethanol on lipids and atherosclerosis

Moderate alcohol consumption is associated with an increase in plasma high density lipoprotein (HDL) cholesterol concentration and a decrease in low density lipoprotein (LDL) cholesterol concentration. Changes in the concentration and composition of lipoproteins are estimated to account for more than half of alcohol's protective effect for coronary heart disease. Alcohol intake also affects plasma proteins involved in lipoprotein metabolism: cholesteryl ester transfer protein, phospholipid transfer protein, lecithin:cholesterol acyltransferase, lipoprotein lipase, hepatic lipase, and phospholipases. In addition, alcohol intake may result in acetaldehyde modification of apolipoproteins. Furthermore, "abnormal" lipids, phosphatidylethanol and fatty acid ethyl esters are formed in the presence of ethanol and are associated with lipoproteins in plasma. Ethanol and ethanol-induced modifications of lipids may modulate the effects of lipoproteins on the cells in the arterial wall. The molecular mechanisms involved in these processes are complex, requiring further study to better understand the specific effects of ethanol in the pathogenesis of atherosclerosis. This review discusses the effects of ethanol on lipoproteins and lipoprotein metabolism, as well as the novel effects of lipoproteins on vascular wall cells.

DEFECTIVE GLYCOSYLATION OF CHOLESTERYL ESTER TRANSFER PROTEIN IN PLASMA FROM ALCOHOL ABUSERS

AIMS

Alcohol consumption reduces the carbohydrate content of some glycoproteins, e.g. carbohydrate-deficient transferrin. The aim of this study was to investigate if there is such an alcohol-induced glycosylation defect in plasma cholesteryl ester transfer protein (CETP). A defect in the posttranslational glycosylation of CETP may affect its structure and electrical charge and may therefore affect its function. CETP activity is low in alcohol abusers.

METHODS

We studied the effect of alcohol consumption on CETP properties in 10 alcohol abusers and 10 control subjects. CETP was partially purified from lipoprotein-free plasma by FPLC using a Phenyl-Sepharose column. Isoelectric focusing, polyacrylamide gel electrophoresis, and western blotting were performed for partially purified CETP.

RESULTS

CETP had a lower molecular weight in the alcohol abusers than in the controls (range 50.6-84.0 kDa in the alcohol abusers vs 51.3-85.0 kDa in the controls). CETP purified from alcohol abusers had a higher isoelectric point, indicating a lower negative charge on the surface of the protein than in the controls' CETP. A similar effect was observed when control CETP was incubated with neuraminidase, an enzyme which is known to remove sialic acid from glycoproteins.

CONCLUSIONS

We conclude that CETP from alcohol abusers may have a glycosylation defect due to defective sialylation caused posttranslationally by alcohol itself or its metabolite acetaldehyde. The defective glycosylation of CETP associated with altered binding to lipoproteins may lead to the low CETP activity observed previously in alcoholic subjects.

A method for determination of phosphatidylethanol from high density lipoproteins by reversed-phase HPLC with TOF–MS detection

Phosphatidylethanol (PEth) is a unique phospholipid that is formed in the body only in the presence of ethanol. According to a new hypothesis, blood high-density lipoprotein (HDL) particles may act as carriers of PEth and mediate part of the antiatherogenic effects of moderate alcohol drinking. Liquid chromatographic method using reversed-phase C8 column and negative ion mode electrospray ionization-mass spectrometry detection with time-of-flight (TOF) instrument was developed for the determination of very small amounts of PEth that might be present on blood HDL particles. The samples used in the current study were human HDL spiked with PEth and internal standard phosphatidylpropanol (PProp). The use of reversed-phase column enabled a short analysis time of 19 min/injection, which is only one-third of the earlier normal-phase methods reported. Because of the narrow bore column (2.1 mm i.d.) and short analysis time, the solvent consumption was decreased. The sensitivity of detection obtained with TOF-MS was better than that of previous methods, with the detection limit being as low as 1 ng/ml in injected sample (20 pg on-column approximately 28 fmol PEth), corresponding to approximately 6.7 ng of PEth in milliliter of unprepared HDL. Good linearity of detection was obtained for a range of 1-100 ng/ml of PEth, whereas all of the deviations in precision and accuracy were less than 15%.

Phosphatidylethanol in high density lipoproteins increases the vascular endothelial growth factor in smooth muscle cells

To study whether qualitative changes in high density lipoprotein (HDL) phospholipids mediate part of the advantageous effects of ethanol on atherosclerosis, we investigated whether HDL associated phosphatidylethanol (PEth) affects the secretion of vascular endothelial growth factor (VEGF) from cultured human smooth muscle cells. Serum-starved human umbilical vein HUVS-112D smooth muscle cells were incubated in the presence of PEth-HDL, HDL, or buffer. The phosphorylation of protein kinase C (PKC) and mitogen activated protein kinase (p44/42 MAPK) was determined by specific antibodies against phosphorylated and total proteins. VEGF concentrations were measured from cell culture medium of the cells. PEth increased the secretion of VEGF into the culture medium of HUVS cells. PEth-HDL increased the PKC phosphorylation by 2.1-fold and p44/42 MAPK phosphorylation by 3.3-fold compared with HDL, indicating that PEth-containing HDL particles influence vascular smooth muscle cells by PKC and p44/42 MAPK signalling. This may mediate the effects of ethanol on vascular wall by increasing the VEGF secretion from smooth muscle cells. The secreted VEGF may inhibit the formation of neointima and in doing so helps prevent atherosclerosis.

A 4-fold risk of metabolic syndrome in patients with schizophrenia: the Northern Finland 1966 Birth Cohort study

OBJECTIVE

Schizophrenia is associated with a shortened life expectancy and increased somatic comorbidity with, e.g., cardiovascular disorders. One major risk factor for these disorders is the metabolic syndrome, which has been reported to have a higher frequency in schizophrenic patients. Our objective was to study the prevalence of metabolic syndrome in a population-based birth cohort.

METHOD

The study sample consisted of 5613 members of the Northern Finland 1966 Birth Cohort who participated in the field study from 1997 to 1998. Subjects were divided into 4 diagnostic categories (DSM-III-R): (1) schizophrenia (N = 31), (2) other functional psychoses (N = 22), (3) nonpsychotic disorders (N = 105), and (4) no psychiatric hospital treatment (N = 5455, comparison group). Subjects were assessed for the presence of metabolic syndrome according to the criteria of the National Cholesterol Education Program.

RESULTS

The prevalence of metabolic syndrome was higher in subjects with schizophrenia compared with the comparison group (19% vs. 6%, p = .010). The prevalence of metabolic syndrome in subjects with other psychoses was 5%. After controlling for sex, the results of logistic regression analysis showed that the risk of metabolic syndrome in schizophrenia was 3.7 (95% CI = 1.5 to 9.0).

CONCLUSIONS

The high prevalence of metabolic syndrome in schizophrenia even at such a relatively young age underscores the need to select antipsychotic medications with no or little capability to induce metabolic side effects. Also, developing comprehensive efforts directed at controlling weight and diet and improving physical activity are needed.

Cholesteryl ester transfer protein TaqIB variant, high-density lipoprotein cholesterol levels, cardiovascular risk, and efficacy of pravastatin treatment: individual patient meta-analysis of 13,677 subjects

BACKGROUND

Several studies have reported that the cholesteryl ester transfer protein (CETP) TaqIB gene polymorphism is associated with HDL cholesterol (HDL-C) levels and the risk of coronary artery disease (CAD), but the results are inconsistent. In addition, an interaction has been implicated between this genetic variant and pravastatin treatment, but this has not been confirmed.

METHODS AND RESULTS

A meta-analysis was performed on individual patient data from 7 large, population-based studies (each >500 individuals) and 3 randomized, placebo-controlled, pravastatin trials. Linear and logistic regression models were used to assess the relation between TaqIB genotype and HDL-C levels and CAD risk. After adjustment for study, age, sex, smoking, body mass index (BMI), diabetes, LDL-C, use of alcohol, and prevalence of CAD, TaqIB genotype exhibited a highly significant association with HDL-C levels, such that B2B2 individuals had 0.11 mmol/L (0.10 to 0.12, P<0.0001) higher HDL-C levels than did B1B1 individuals. Second, after adjustment for study, sex, age, smoking, BMI, diabetes, systolic blood pressure, LDL-C, and use of alcohol, TaqIB genotype was significantly associated with the risk of CAD (odds ratio=0.78 [0.66 to 0.93]) in B2B2 individuals compared with B1B1 individuals (P for linearity=0.008). Additional adjustment for HDL-C levels rendered a loss of statistical significance (P=0.4). Last, no pharmacogenetic interaction between TaqIB genotype and pravastatin treatment could be demonstrated.

CONCLUSIONS

The CETP TaqIB variant is firmly associated with HDL-C plasma levels and as a result, with the risk of CAD. Importantly, this CETP variant does not influence the response to pravastatin therapy.

Transfer of Phosphatidylethanol Between Lipoproteins

BACKGROUND

Phosphatidylethanol (PEth) is an abnormal phospholipid formed only in the presence of ethanol. It has been recently shown that lipoprotein-associated PEth may mediate the effects of ethanol on endothelial cells, and this may explain, at least in part, the beneficial effect of ethanol on atherosclerosis. This study was performed to investigate the transfer of PEth between lipoproteins and the effects of PEth on cholesteryl ester transfer protein (CETP) activity in plasma.

METHODS

Lipoproteins were isolated from the plasma of healthy male volunteers (n = 16) and male alcoholics (n = 13). The transfer of cholesteryl esters and PEth was determined between labeled low-density lipoprotein (LDL) and unlabeled high-density lipoprotein particles in vitro. The electrophoretic mobility of PEth-modified LDL particles was determined by agarose gel electrophoresis.

RESULTS

PEth was transferred from PEth-modified LDL to high-density lipoprotein at an initial rate of 25.9 nmol/ml/hr. Monoclonal antibody (TP2) against the putative lipid-binding domain of CETP inhibited the transfer rate of PEth by approximately 64%, whereas the cholesteryl ester transfer was inhibited by 86%. This indicates that most of PEth was transferred by transfer proteins other than CETP.

CONCLUSIONS

The transfer of PEth between lipoproteins enables the redistribution of PEth from lipoprotein fractions with a slow turnover to those with a rapid clearance. Moreover, the PEth-induced change in the electrical charge of lipoproteins may affect the binding of lipoproteins to their receptors and binding proteins. This in turn may alter the metabolism of lipoproteins and lipid-mediated signaling pathways in the cells delineating the vascular wall.

Effects of estrogen replacement therapy on natriuretic peptides and blood pressure

OBJECTIVE

Estrogen replacement therapy (ERT) has been reported to affect blood pressure. Since natriuretic peptides have natriuretic and vasodilatory activity and also inhibit the renin-angiotensin-aldosterone system and lower blood pressure, it was hypothesized that the changes in blood pressure effected by ERT might be mediated via changes in natriuretic peptides.

METHODS

Fifty-eight postmenopausal hysterectomized women were randomized in a double-blind, double-dummy study to receive either peroral estradiol valerate 2 mg/day or transdermal estradiol gel containing 1 mg estradiol/day for 6 months. Blood pressure was measured by using an automatic, oscillometric device. Plasma atrial natriuretic peptide (ANP), N-terminal fragment of proANP (NT-proANP), B-type natriuretic peptide (BNP), aldosterone, and renin were determined by radioimmunoassay.

RESULTS

The mean decrease in diastolic blood pressure was -6 mmHg both in the peroral group (n = 26) (P = 0.002) and in the gel group (n = 27) (P = 0.001), and the corresponding decreases in systolic blood pressure were -4 mmHg (P = 0.070) and -7 mmHg (P = 0.028) in the sitting position. Plasma NT-proANP rose from 212 to 264 pmol/l (P = 0.001) on peroral ERT and from 240 to 292 pmol/l (P = 0.008) on transdermal ERT. No significant changes were observed in the plasma ANP, BNP, aldosterone, and renin levels.

CONCLUSIONS

Both peroral and transdermal ERT result in elevated plasma levels of NT-proANP, indicating an activation of the natriuretic peptide system. This could explain, at least in part, the lowering of blood pressure during ERT.

Lipoprotein-Associated Phosphatidylethanol Increases the Plasma Concentration of Vascular Endothelial Growth Factor

OBJECTIVE

To study whether qualitative changes in high-density lipoprotein (HDL) phospholipids mediate part of the beneficial effects of alcohol on atherosclerosis, we investigated whether phosphatidylethanol (PEth) in HDL particles affects the secretion of vascular endothelial growth factor (VEGF) from endothelial cells.

METHODS AND RESULTS

PEth increased the secretion of VEGF into the culture medium of EA.hy 926 endothelial cells. The mitogen-activated protein kinase (MAPK) phosphorylation increased by 3.3-fold and protein kinase C (PKC) by 2.2-fold by PEth-containing HDL. Moreover, we showed that intravenous injection of PEth incorporated into HDL particles increased plasma concentration of VEGF by 2.4-fold in rats in vivo. Similar effect was observed when the rats were injected with HDL particles isolated from alcohol drinkers.

CONCLUSIONS

HDL particles containing PEth affect endothelial cells by MAPK and PKC signaling. This may mediate the effects of ethanol on the arterial wall by increasing VEGF secretion from endothelial vascular cells. That may explain, at least in part, the beneficial effect of moderate alcohol consumption on atherosclerosis.

Candidate locus analysis of familial ascending aortic aneurysms and dissections confirms the linkage to the chromosome 5q13-14 in Finnish families

OBJECTIVE

The purpose of the study was to carry out a candidate gene analysis in families with familial thoracic aortic aneurysms and dissections.

METHODS

The study material consisted of 11 Finnish families (with 115 members genotyped) who underwent echocardiographic examination for measurement of the aortic root diameter. Selected candidate genes included the loci for Marfan and Ehlers-Danlos syndromes, the genes of matrix metalloproteinases 3 and 9 and tissue inhibitor of metalloproteinase 2 as well two loci on the chromosomes 5q13-14 and 11q23.2-q24, previously found to be linked to the disease.

RESULTS

The chromosomal locus 5q13-14 was linked to the disease risk (nonparametric linkage score 3.0, P =.005) confirming the previous linkage. Other candidate genes and loci were excluded as major loci in these families.

CONCLUSIONS

The identification of the gene at chromosomal location 5q13-14 causing the development of such diseases would give us important knowledge on the pathogenesis of the disease and enable the identification of subjects at risk. This in turn would lead to appropriate treatment before the occurrence of fatal complications and, likely, to the development of new treatment methods.

High-density lipoprotein increases the abundance of eNOS protein in human vascular endothelial cells by increasing its half-life

OBJECTIVES

Given the importance of endothelial nitric oxide synthase (eNOS) in regulating endothelium-dependent vasorelaxation, we investigated the effects of high-density lipoprotein in (HDL) on eNOS protein abundance in cultured human vascular endothelial cells.

BACKGROUND

Endothelial dysfunction, characterized by decreased nitric oxide production, is one of the early features in the development of atherosclerosis. We have recently shown in vivo that niacin therapy increases plasma HDL concentration and improves endothelium-dependent vasorelaxation in patients with coronary artery disease.

METHODS

Human vascular endothelial cells were cultured in the presence or absence of HDL or apolipoprotein (apo)A-I. The eNOS protein abundance was assessed by immunoblotting, and protein half-life was assessed by pulse-chase techniques. The eNOS messenger ribonucleic acid (mRNA) abundance was measured using real-time quantitative polymerase chain reaction.

RESULTS

High density lipoprotein, or apoA-I alone, increased eNOS protein abundance by 3.5 +/- 0.7 and 2.7 +/- 0.5-fold, respectively (p < 0.05 for both). However, neither HDL nor apoA-I increased eNOS mRNA abundance. It was shown that HDL increased eNOS protein half-life up to 3.3 +/- 0.2-fold (p = 0.001). Both HDL and apoA-I activated mitogen-activated protein-kinase and phosphatidylinositol 3-kinase (PI3K) Akt-pathways in human arterial endothelial cells, and inhibition of either of these pathways by specific pharmacologic inhibitors abolished the effect of HDL on eNOS.

CONCLUSIONS

We demonstrate that HDL activates both extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt, resulting in enhanced eNOS protein stability and subsequent accumulation of eNOS protein. This posttranslational regulation represents a previously unrecognized mechanism for regulating eNOS.