A Comparison of Three Different Methods to Evaluate Endothelium-Dependent Vasodilation in the Elderly

Genome-wide association study of caffeine metabolites provides new insights to caffeine metabolism and dietary caffeine-consumption behavior

Caffeine is the most widely consumed psychoactive substance in the world and presents with wide interindividual variation in metabolism. This variation may modify potential adverse or beneficial effects of caffeine on health. We conducted a genome-wide association study (GWAS) of plasma caffeine, paraxanthine, theophylline, theobromine and paraxanthine/caffeine ratio among up to 9,876 individuals of European ancestry from six population-based studies. A single SNP at 6p23 (near CD83) and several SNPs at 7p21 (near AHR), 15q24 (near CYP1A2) and 19q13.2 (near CYP2A6) met GW-significance (P < 5 × 10-8) and were associated with one or more metabolites. Variants at 7p21 and 15q24 associated with higher plasma caffeine and lower plasma paraxanthine/caffeine (slow caffeine metabolism) were previously associated with lower coffee and caffeine consumption behavior in GWAS. Variants at 19q13.2 associated with higher plasma paraxanthine/caffeine (slow paraxanthine metabolism) were also associated with lower coffee consumption in the UK Biobank (n = 94 343, P < 1.0 × 10-6). Variants at 2p24 (in GCKR), 4q22 (in ABCG2) and 7q11.23 (near POR) that were previously associated with coffee consumption in GWAS were nominally associated with plasma caffeine or its metabolites. Taken together, we have identified genetic factors contributing to variation in caffeine metabolism and confirm an important modulating role of systemic caffeine levels in dietary caffeine consumption behavior. Moreover, candidate genes identified encode proteins with important clinical functions that extend beyond caffeine metabolism.

DNA methylation patterns associated with oxidative stress in an ageing population

Background

Oxidative stress has been related to type 2 diabetes (T2D) and cardiovascular disease (CVD), the leading global cause of death. Contributions of environmental factors such as oxidative stress on complex traits and disease may be partly mediated through changes in epigenetic marks (e.g. DNA methylation). Studies relating differential methylation with intermediate phenotypes and disease endpoints may be useful in identifying additional candidate genes and mechanisms involved in disease.

Methods

To investigate the role of epigenetic variation in oxidative stress marker levels and subsequent development of CVD and T2D, we performed analyses of genome-wide DNA methylation in blood, ten markers of oxidative stress (total glutathione [TGSH], reduced glutathione [GSH], oxidised glutathione [GSSG], GSSG to GSH ratio, homocysteine [HCY], oxidised low-density lipoprotein (oxLDL), antibodies against oxLDL [OLAB], conjugated dienes [CD], baseline conjugated dienes [BCD]-LDL and total antioxidant capacity [TAOC]) and incident disease in up to 966 age-matched individuals.

Results

In total, we found 66 cytosine-guanine (CpG) sites associated with one or more oxidative stress markers (false discovery rate [FDR] <0.05). These sites were enriched in regulatory regions of the genome. Genes annotated to CpG sites showed enrichment in annotation clusters relating to phospho-metabolism and proteins with pleckstrin domains. We investigated the contribution of oxidative stress-associated CpGs to development of cardiometabolic disease. Methylation variation at CpGs in the 3'-UTR of HIST1H4D (cg08170869; histone cluster 1, H4d) and in the body of DVL1 (cg03465880; dishevelled-1) were associated with incident T2D events during 10 years of follow-up (all permutation p-values <0.01), indicating a role of epigenetic regulation in oxidative stress processes leading to development or progression of diabetes. Methylation QTL (meQTL) analysis showed significant associations with genetic sequence variants in cis at 28 (42%) of oxidative stress phenotype-associated sites (FDR < 0.05). Integrating cis-meQTLs with genotype-phenotype associations indicated that genetic effects on oxidative stress phenotype at one locus (cg07547695; BCL2L11) may be mediated through DNA methylation.

Conclusions

In conclusion, we report novel associations of DNA methylation with oxidative stress, some of which also show evidence of a relation with T2D incidence.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-016-0235-0) contains supplementary material, which is available to authorized users.

The effects of alpha 1-adrenoceptor blockade and angiotensin converting enzyme inhibition on central and brachial blood pressure and vascular reactivity: the doxazosin-ramipril study

We aimed to study whether inhibition of the renin–angiotensin–aldosterone system has effects on vascular structure and function beyond the effects on blood pressure reduction alone. Patients with mild-to-moderate hypertension (n = 61, age 54 ± 12 years, 34% women) received the angiotensin converting enzyme inhibitor ramipril 10 mg or the alpha 1-adrenoceptor blocker doxazosin 8 mg double-blind for 12 weeks. Aortic blood pressure, pulse wave velocity, and augmentation index were assessed by applanation tonometry. Endothelial function was studied by forearm post-ischemic flow mediated vasodilatation and by pulse wave analysis with beta 2-adrenoceptor agonist stimulation. Skin microvascular reactivity was assessed by laser Doppler fluxmetry and iontophoresis. Treatment with doxazosin or ramipril reduced aortic and brachial blood pressures (all P < 0.001), with greater reductions in aortic than brachial systolic blood pressures (P = 0.021) and aortic/brachial pulse pressure ratio (P = 0.005). Compared to doxazosin, ramipril reduced carotid-femoral and carotid-radial pulse wave velocity (both P < 0.05). Forearm endothelial dependent and independent vasodilatation, assessed by post-ischemic flow mediated vasodilatation and glyceryl trinitrate, and by pulse wave analysis remained unchanged by both doxazosin and ramipril. In addition, skin microvascular endothelial dependent (acetylcholine) and independent vasodilatation (sodium nitroprusside) remained unchanged. In conclusion, ramipril reduced indices of aortic stiffness, suggesting that angiotensin converting enzyme inhibitor therapy may have effects beyond blood pressure reduction. However, treatment did not appear to influence endothelial function. Evidence of endothelial dysfunction and its possible improvement by antihypertensive treatment might require more advanced hypertension.

This study is registered at ClinicalTrials.gov (NCT02901977) and at EudraCT (# 2007-000631-25).

Use of a proximity extension assay proteomics chip to discover new biomarkers associated with albuminuria

Background The underlying mechanisms for the development of albuminuria and the increased cardiovascular risk in patients with elevated albuminuria levels are incompletely understood. We therefore investigated the associations between 80 cardiovascular proteins and the urinary albumin to creatinine ratio (ACR). Methods We used a discovery/replication approach in two independent community-based cohorts of elderly patients: the Uppsala Longitudinal Study of Adult Men ( n = 662; mean age 78 years) and the Prospective Investigation of the Vasculature in Uppsala Seniors ( n = 757; mean age 75 years; 51% women). A proteomic chip with a panel of 80 plasma proteins associated with different aspects of cardiovascular disease was analysed. In the discovery cohort, we used a false discovery rate of 5% to take into account the multiple statistical testing. Nominal p values were used in the replication. Results Higher levels of T-cell immunoglobulin mucin-1, placenta growth factor, growth/differentiation factor-15, urokinase plasminogen activator surface receptor and kallikrein-11 were robustly associated with a higher ACR in both cohorts in multivariable linear regression models adjusted for sex, established cardiovascular risk factors, antihypertensive treatment, prevalent cardiovascular disease and glomerular filtration rate ( p < 0.02 for all). All associations were also significant in separate analyses of patients without diabetes. Conclusions We discovered and replicated associations between ACR and five cardiovascular proteins involved in tubular injury, atherosclerosis, endothelial function, heart failure, inflammation, glomerulosclerosis and podocyte injury. Our findings put forward multiplex proteomics as a promising approach to explore novel aspects of the complex detrimental interplay between kidney function and the cardiovascular system.

Population attributable risks and costs of diabetogenic chemical exposures in the elderly

Background

A previous analysis examined the contribution of endocrine disruptor exposures (endocrine-disrupting chemicals, EDCs) to adult diabetes, but was limited to effects of phthalates in middle-aged women and did not simultaneously examine multiple EDCs which are known to coexist in the environment. We therefore endeavoured to quantify potential reductions in diabetes and disease costs that could result from reducing synthetic chemical diabetogenic exposures in the elderly in Europe.

Methods

We leveraged the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study (∼1000 participants), which has measured exposure to phthalates; dichlorodiphenyltrichloroethylene; polychlorinated biphenyls (PCBs) and perfluoroalkyl substances to examine their independent contribution to diabetes. We estimated risk reductions assuming identical 25% reductions across levels of 4 selected compounds (PCB 153, monoethylphthalate, dichlorodiphenyldichloroethylene and perfluorononanoic acid), and diabetes costs saved in European men and women if diabetogenic exposures are limited.

Results

Reduction of chemical exposures was associated with a 13% (95% CI 2% to 22%) reduction in prevalent diabetes, compared with 40% resulting from an identical (25%) reduction in body mass index (BMI) in cross-sectional analyses. Extrapolating to Europe, 152 481 cases of diabetes in Europe and €4.51 billion/year in associated costs could be prevented, compared with 469 172 cases prevented by reducing BMI.

Conclusions

These findings support regulatory and individual efforts to reduce chemical exposures to reduce the burden and costs of diabetes.

Metabolic Syndrome Development During Aging with Special Reference to Obesity Without the Metabolic Syndrome

BACKGROUND

Obesity and its associated metabolic complications continue to increase worldwide. We investigated the development of metabolic syndrome (MetS) during aging in relation to body mass index (BMI) and exercise habits. We assigned special emphasis to the metabolic stability in individuals with obesity, but without MetS, a condition often referred to as metabolically healthy obesity.

MATERIALS AND METHODS

Cross-sectional analysis was carried out in a sample of 19,129 men and women aged 45-75 years from the EpiHealth study. In addition, longitudinal analyses were carried out in the ULSAM study (2322 men at baseline followed from age 50 to age 77) and in the PIVUS study (1016 men and women at baseline followed from age 70 to age 80). Participants were categorized into six groups according to BMI category (normal weight/BMI <25 kg/m², overweight/BMI 25-30 kg/m², and obesity/BMI >30 kg/m²) and MetS status (+/-, National Cholesterol Education Program criteria).

RESULTS

MetS prevalence and number of MetS components increased with age in all three samples. The PIVUS study showed that high baseline BMI, low baseline physical activity, and increasing BMI during follow-up were related to increasing MetS prevalence and increasing numbers of MetS components during follow-up. One-third to half of individuals initially belonging to the obesity without MetS category acquired MetS during aging.

CONCLUSIONS

MetS prevalence increased during aging, especially in individuals with high BMI, low level of physical activity, and weight gain. Obesity without MetS was not a stable condition over time as many of those individuals gained metabolic disturbances during aging.

Non-targeted metabolomics combined with genetic analyses identifies bile acid synthesis and phospholipid metabolism as being associated with incident type 2 diabetes

AIMS/HYPOTHESIS

Identification of novel biomarkers for type 2 diabetes and their genetic determinants could lead to improved understanding of causal pathways and improve risk prediction.

METHODS

In this study, we used data from non-targeted metabolomics performed using liquid chromatography coupled with tandem mass spectrometry in three Swedish cohorts (Uppsala Longitudinal Study of Adult Men [ULSAM], n = 1138; Prospective Investigation of the Vasculature in Uppsala Seniors [PIVUS], n = 970; TwinGene, n = 1630). Metabolites associated with impaired fasting glucose (IFG) and/or prevalent type 2 diabetes were assessed for associations with incident type 2 diabetes in the three cohorts followed by replication attempts in the Cooperative Health Research in the Region of Augsburg (KORA) S4 cohort (n = 855). Assessment of the association of metabolite-regulating genetic variants with type 2 diabetes was done using data from a meta-analysis of genome-wide association studies.

RESULTS

Out of 5961 investigated metabolic features, 1120 were associated with prevalent type 2 diabetes and IFG and 70 were annotated to metabolites and replicated in the three cohorts. Fifteen metabolites were associated with incident type 2 diabetes in the four cohorts combined (358 events) following adjustment for age, sex, BMI, waist circumference and fasting glucose. Novel findings included associations of higher values of the bile acid deoxycholic acid and monoacylglyceride 18:2 and lower concentrations of cortisol with type 2 diabetes risk. However, adding metabolites to an existing risk score improved model fit only marginally. A genetic variant within the CYP7A1 locus, encoding the rate-limiting enzyme in bile acid synthesis, was found to be associated with lower concentrations of deoxycholic acid, higher concentrations of LDL-cholesterol and lower type 2 diabetes risk. Variants in or near SGPP1, GCKR and FADS1/2 were associated with diabetes-associated phospholipids and type 2 diabetes.

CONCLUSIONS/INTERPRETATION

We found evidence that the metabolism of bile acids and phospholipids shares some common genetic origin with type 2 diabetes.

ACCESS TO RESEARCH MATERIALS

Metabolomics data have been deposited in the Metabolights database, with accession numbers MTBLS93 (TwinGene), MTBLS124 (ULSAM) and MTBLS90 (PIVUS).

Circulating levels of perfluoroalkyl substances are associated with dietary patterns - A cross sectional study in elderly Swedish men and women

BACKGROUND

In our daily life, we are exposed to perfluoroalkyl substances (PFAS) with possible health implications. The main exposure route for these substances is diet but comparative studies on how dietary habits influence exposure are lacking.

OBJECTIVES

To examine the relations between blood levels of PFAS and adherence to three predefined dietary patterns (a WHO recommended diet, a Mediterranean-like diet, and a Low-Carbohydrate High-Protein (LCHP) diet) in an elderly Swedish population.

METHODS

Dietary data from 7-day food records and serum concentrations of PFAS were obtained from a 70-year-old Swedish population (n=844), the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. The Healthy Diet Indicator score (based on WHO recommendations), the Mediterranean Diet Score and LCHP score were used to assess adherence. Multivariate linear regression was used to assess the associations between eight major PFAS and adherence to each dietary pattern.

RESULTS

The WHO recommended diet was positively associated with perfluorohexane sulfonic acid (PFHxS). The LCHP diet was positively related to four out of eight PFAS; namely, perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnDA). The Mediterranean-like diet was positively associated with most PFAS; namely perfluorooctanoic acid (PFOA), perfluorooctane sulfonamide (PFOSA), PFHxS, PFNA, PFDA, and PFUnDA.

CONCLUSIONS

All dietary patterns were positively associated with blood levels of PFAS. The highest body burden of PFAS was found in individuals with high adherence to a Mediterranean-like diet, whilst individuals who more closely followed the officially recommended diet displayed a lower body burden of these compounds.

Effects of cigarette smoking on cardiovascular-related protein profiles in two community-based cohort studies

BACKGROUND AND AIMS

Cardiovascular diseases account for the largest fraction of smoking-induced deaths. Studies of smoking in relation to cardiovascular-related protein markers can provide novel insights into the biological effects of smoking. We investigated the associations between cigarette smoking and 80 protein markers known to be related to cardiovascular diseases in two community-based cohorts, the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS, n = 969, 50% women, all aged 70 years) and the Uppsala Longitudinal Study of Adult Men (ULSAM, n = 717, all men aged 77 years).

METHODS

Smoking status was self-reported and defined as current smoker, former smoker or never-smoker. Levels of the 80 proteins were measured using the proximity extension assay, a novel PCR-based proteomics technique.

RESULTS

We found 30 proteins to be significantly associated with current cigarette smoking in PIVUS (FDR<5%); and ten were replicated in ULSAM (p < 0.05). Matrix metalloproteinase-12 (MMP-12), growth/differentiation factor 15 (GDF-15), urokinase plasminogen activator surface receptor (uPAR), TNF-related apoptosis-inducing ligand receptor 2 (TRAIL-R2), lectin-like oxidized LDL receptor 1 (LOX-1), hepatocyte growth factor (HGF), matrix metalloproteinase-10 (MMP-10) and matrix metalloproteinase-1 (MMP-1) were positively associated, while endothelial cell-specific molecule 1 (ESM-1) and interleukin-27 subunit alpha (IL27-A) showed inverse associations. All of them remained significant in a subset of individuals without manifest cardiovascular disease.

CONCLUSIONS

The findings of the present study suggest that cigarette smoking may interfere with several essential parts of the atherosclerosis process, as evidenced by associations with protein markers representing endothelial dysfunction, inflammation, neointimal formation, foam cell formation and plaque instability.

Discovery of new biomarkers for atrial fibrillation using a custom-made proteomics chip

BACKGROUND

Apart from several established clinical risk factors for atrial fibrillation (AF), a number of biomarkers have also been identified as potential risk factors for AF. None of these have so far been adopted in clinical practice.

OBJECTIVE

To use a novel custom-made proteomics chip to discover new prognostic biomarkers for AF risk.

METHODS

In two independent community-based cohorts (Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study (978 participants without AF, mean age 70.1 years, 50% women, median follow-up 10.0 years) and Uppsala Longitudinal Study of Adult Men (ULSAM) (n=725, mean age 77.5 years, median follow-up 7.9 years)), ninety-two plasma proteins were assessed at baseline by a proximity extension assay (PEA) chip. Of those, 85 proteins showed a call rate >70% in both cohorts.

RESULTS

Thirteen proteins were related to incident AF in PIVUS (148 events) using a false discovery rate of 5%. Of those, five were replicated in ULSAM at nominal multivariable p value (123 events, N-terminal pro-B-type natriuretic peptide (NT-pro-BNP), fibroblast growth factor 23 (FGF-23), fatty acid-binding protein 4 (FABP4), growth differentiation factor 15 (GDF-15) and interleukin-6 (IL-6)). Of those, NT-pro-BNP and FGF-23 were also associated with AF after adjusting for established AF risk factors. In a prespecified secondary analysis pooling the two data sets, T-cell immunoglobulin and mucin domain 1 (TIM-1) and adrenomedullin (AM) were also significantly related to incident AF in addition to the aforementioned five proteins (Bonferroni-adjustment). The addition of NT-pro-BNP to a model with established risk factors increased the C-statistic from 0.605 to 0.676 (p<0.0001).

CONCLUSIONS

Using a novel proteomics approach, we confirmed the previously reported association between NT-pro-BNP, FGF-23, GDF-15 and incident AF, and also discovered four proteins (FABP4, IL-6, TIM-1 and AM) that could be of importance in the development of AF.

Nonparametric estimation of the rediscovery rate

Validation studies have been used to increase the reliability of the statistical conclusions for scientific discoveries; such studies improve the reproducibility of the findings and reduce the possibility of false positives. Here, one of the important roles of statistics is to quantify reproducibility rigorously. Two concepts were recently defined for this purpose: (i) rediscovery rate (RDR), which is the expected proportion of statistically significant findings in a study that can be replicated in the validation study and (ii) false discovery rate in the validation study (vFDR). In this paper, we aim to develop a nonparametric approach to estimate the RDR and vFDR and show an explicit link between the RDR and the FDR. Among other things, the link explains why reproducing statistically significant results even with low FDR level may be difficult. Two metabolomics datasets are considered to illustrate the application of the RDR and vFDR concepts in high-throughput data analysis. Copyright © 2016 John Wiley & Sons, Ltd.

Urinary KIM-1, but not urinary cystatin C, should be corrected for urinary creatinine

OBJECTIVES

The interest for tubular damage markers such as urinary cystatin C (U-CystC) and kidney injury molecule-1 (U-KIM-1) grows, especially for the diagnosis of acute kidney injury. The trend to measure proteins in spot urine samples instead of 24-h urine collections calls for adjustment of urine dilution with urinary creatinine (UCr). However, it is not known whether UCr adjustment provides a more true value of basal U-CystC and U-KIM-1 levels than absolute values.

DESIGN & METHODS

This study examines the rationale for UCr correction for U-CystC and U-KIM-1 by exploring the linear relations between U-CystC and U-KIM-1 and UCr, respectively, and the biological day to day variation of absolute concentrations and UCr adjusted values of the two biomarkers.

RESULTS

Both U-CystC and U-KIM-1 concentrations correlated positively with UCr (R=0.37, P<0.001 and R=0.62, P<0.001, respectively) in 378 participants in a community cohort, which indicated a rationale for adjustment with UCr. However, U-CystC/Cr ratio associated negatively with UCr (R=- 0.31, P<0.001), which could indicate a certain amount of 'over-adjustment'. Morning urine collected for 10 consecutive days from 13 healthy volunteers showed a biological day to day variation of 82% for U-CystC, 75% for U-cystC/Cr ratio, 70% for U-KIM-1 and 46% for U-KIM-1/Cr ratio.

CONCLUSIONS

This study supports the use of U-KIM-1/Cr ratio in clinical population studies. Data supporting the use of U-CysC/U-Cr ratio were less convincing and the possible confounding of UCr has to be acknowledged in clinical settings.

Long-term prognosis of unrecognized myocardial infarction detected with cardiovascular magnetic resonance in an elderly population

BACKGROUND

Individuals with unrecognized myocardial infarctions (UMIs) detected with cardiovascular magnetic resonance (CMR) constitute a recently defined group whose prognosis has not been fully evaluated. However, increasing evidence indicate that these individuals may be at considerable cardiovascular risk. The aim of the present study was to investigate the prognostic impact of CMR detected UMIs for major adverse cardiac events (MACE) in community living elderly individuals.

METHODS

Late gadolinium enhancement CMR was performed in 248 randomly chosen 70-year-olds. Individuals with myocardial infarction (MI) scars, with or without a hospital diagnosis of MI were classified as recognized MI (RMI) or UMI, respectively. Medical records and death certificates were scrutinized. MACE was defined as cardiac death, non-fatal MI, a new diagnosis of angina pectoris, or symptom-driven coronary artery revascularization.

RESULTS

During follow-up (mean 11 years) MACE occurred in 10 % (n = 18/182) of the individuals without MI scars, in 20 % (n = 11/55) of the individuals with UMI, and in 45 % (n = 5/11) of the individuals with RMI, with a significant difference between the UMI group and the group without MI scars (p = 0.045), and between the RMI group and the group without MI scars (p = 0.0004). Cardiac death and/or non-fatal MI occurred in 15, 5, and 3 of the individuals in the NoMI, UMI, and RMI group respectively. Hazards ratios for MACE adjusted for risk factors and sex were 2.55 (95 % CI 1.20-5.42; p = 0.015) for UMI and 3.28 (95 % CI1.16-9.22; p = 0.025) for RMI.

CONCLUSIONS

The presence of a CMR detected UMI entailed a more than double risk for MACE in community living 70-year-old individuals.

Mosaic Loss of Chromosome Y in Blood Is Associated with Alzheimer Disease

Men have a shorter life expectancy compared with women but the underlying factor(s) are not clear. Late-onset, sporadic Alzheimer disease (AD) is a common and lethal neurodegenerative disorder and many germline inherited variants have been found to influence the risk of developing AD. Our previous results show that a fundamentally different genetic variant, i.e., lifetime-acquired loss of chromosome Y (LOY) in blood cells, is associated with all-cause mortality and an increased risk of non-hematological tumors and that LOY could be induced by tobacco smoking. We tested here a hypothesis that men with LOY are more susceptible to AD and show that LOY is associated with AD in three independent studies of different types. In a case-control study, males with AD diagnosis had higher degree of LOY mosaicism (adjusted odds ratio = 2.80, p = 0.0184, AD events = 606). Furthermore, in two prospective studies, men with LOY at blood sampling had greater risk for incident AD diagnosis during follow-up time (hazard ratio [HR] = 6.80, 95% confidence interval [95% CI] = 2.16–21.43, AD events = 140, p = 0.0011). Thus, LOY in blood is associated with risks of both AD and cancer, suggesting a role of LOY in blood cells on disease processes in other tissues, possibly via defective immunosurveillance. As a male-specific risk factor, LOY might explain why males on average live shorter lives than females.

Oral trehalose supplementation improves resistance artery endothelial function in healthy middle-aged and older adults

We hypothesized that supplementation with trehalose, a disaccharide that reverses arterial aging in mice, would improve vascular function in middle-aged and older (MA/O) men and women. Thirty-two healthy adults aged 50-77 years consumed 100 g/day of trehalose (n=15) or maltose (n=17, isocaloric control) for 12 weeks (randomized, double-blind). In subjects with Δbody mass less than 2.3kg (5 lb.), resistance artery endothelial function, assessed by forearm blood flow to brachial artery infusion of acetylcholine (FBFACh), increased ~30% with trehalose (13.3±1.0 vs. 10.5±1.1 AUC, P=0.02), but not maltose (P=0.40). This improvement in FBFACh was abolished when endothelial nitric oxide (NO) production was inhibited. Endothelium-independent dilation, assessed by FBF to sodium nitroprusside (FBFSNP), also increased ~30% with trehalose (155±13 vs. 116±12 AUC, P=0.03) but not maltose (P=0.92). Changes in FBFACh and FBFSNP with trehalose were not significant when subjects with Δbody mass ≥ 2.3kg were included. Trehalose supplementation had no effect on conduit artery endothelial function, large elastic artery stiffness or circulating markers of oxidative stress or inflammation (all P>0.1) independent of changes in body weight. Our findings demonstrate that oral trehalose improves resistance artery (microvascular) function, a major risk factor for cardiovascular diseases, in MA/O adults, possibly through increasing NO bioavailability and smooth muscle sensitivity to NO.

The metabolic fingerprint of p,p'-DDE and HCB exposure in humans

BACKGROUND

Dichlorodiphenyldichloroethylene (p,p'-DDE) and hexachlorobenzene (HCB) are organochlorine pesticides with well-known endocrine disrupting properties. Exposure to p,p'-DDE and HCB concerns human populations worldwide and has been linked to metabolic disorders such as obesity and type 2 diabetes, but details about these associations in humans from the general population are largely unknown.

OBJECTIVES

We investigated the associations between p,p'-DDE and HCB exposure and global metabolomic profiles in serum samples from 1016 participants from the Swedish population-based Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study.

METHODS

HCB and p,p'-DDE levels were determined using gas chromatography coupled to high-resolution mass spectrometry (GC-HRMS). Metabolite levels were determined by using a non-targeted metabolomics approach with ultra-performance liquid chromatography coupled to time-of- flight mass spectrometry (UPLC-TOFMS). Association analyses were performed using multivariate linear regression.

RESULTS

We found circulating levels of p,p-DDE and HCB to be significantly associated with circulating levels of 16 metabolites following adjustment for age, sex, education level, exercise habits, smoking, energy intake, and alcohol intake. The majority of the 16 metabolites belong to lipid metabolism pathways and include fatty acids, glycerophospholipids, sphingolipids, and glycerolipids. Overall, p,p'-DDE and HCB levels were found to be correlated to different metabolites, which suggests that different metabolic fingerprints may be related to circulating levels of these two pesticides.

CONCLUSIONS

Our findings establish a link between human exposure to organochlorine pesticides and metabolites of key metabolic processes mainly related to human lipid metabolism.

Evaluation of Temporal Changes in Cardiovascular Biomarker Concentrations Improves Risk Prediction in an Elderly Population from the Community

BACKGROUND

There is increasing interest in measurements of cardiovascular (CV) biomarker concentrations for risk prediction in the general population. We investigated the prognostic utility of a panel of novel CV biomarkers including biomarker changes over time.

METHODS

We measured concentrations of N-terminal pro-B-type natriuretic peptide (NT-proBNP), midregional proadrenomedullin, high-sensitivity cardiac troponin I, growth-differentiation factor-15 (GDF-15), soluble ST2 (sST2), and galectin-3 at baseline and 5 years later in 1016 elderly individuals participating in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Assessed outcomes included all-cause mortality and fatal and nonfatal CV events (in participants without CV disease at baseline) during 10 years of follow-up.

RESULTS

GDF-15 exhibited the strongest association with all-cause mortality (n = 158) with a hazard ratio (HR) per 1-SD increase in standardized ln GDF-15 of 1.68 (95% CI, 1.44–1.96). NT-proBNP was the only biomarker to predict CV events (n = 163; HR 1.54 [95% CI, 1.30–1.84]). GDF-15 and NT-proBNP also improved metrics of discrimination and reclassification of the respective outcomes. Changes in GDF-15 concentrations between 70 and 75 years predicted all-cause mortality whereas changes in NT-proBNP predicted both outcomes. The other biomarkers and their temporal changes provided only moderate prognostic value apart from sST2 which had a neutral relationship with adverse events.

CONCLUSIONS

Evaluation of temporal changes in GDF-15 and NT-proBNP concentrations improves risk prediction in an elderly population. These findings are of considerable interest given the emphasis on biomarkers as tools to identify and monitor at-risk individuals with preclinical and potentially modifiable stages of CV disease.

Genome-wide DNA methylation study identifies genes associated with the cardiovascular biomarker GDF-15

Growth-differentiation factor 15 (GDF-15) is expressed in low to moderate levels in most healthy tissues and increases in response to inflammation. GDF-15 is associated with cardiovascular dysfunction and over-expressed in the myocardium of patients with myocardial infarction (MI). However, little is known about the function of GDF-15 in cardiovascular disease, and the underlying regulatory network of GDF-15 is not known. To investigate a possible association between GDF-15 levels and DNA methylation, we performed a genome-wide DNA methylation study of white blood cells in a population-based study (N = 717). Significant loci where replicated in an independent cohort (N = 963). We also performed a gene ontology (GO) enrichment analysis. We identified and replicated 16 CpG-sites (false discovery rate [FDR] < 0.05), at 11 independent loci including MIR21. MIR21 encodes a microRNA (miR-21) that has previously been shown to be associated with the development of heart disease. Interestingly, GDF15 mRNA contains a binding site for miR-21. Four sites were also differentially methylated in blood from participants previously diagnosed with MI and 14 enriched GO terms (FDR < 0.05, enrichment > 2) were identified, including 'cardiac muscle cell differentiation'. This study shows that GDF-15 levels are associated with differences in DNA methylation in blood cells, and a subset of the loci are also differentially methylated in participants with MI. However, there might be interactions between GDF-15 levels and methylation in other tissues not addressed in this study. These results provide novel links between GDF-15 and cardiovascular disease.

Discovery of New Risk Markers for Ischemic Stroke Using a Novel Targeted Proteomics Chip

BACKGROUND AND PURPOSE

Emerging technologies have made it possible to simultaneously evaluate a large number of circulating proteins as potential new stroke risk markers.

METHODS

We explored associations between 85 cardiovascular proteins, assessed by a proteomics chip, and incident ischemic stroke in 2 independent cohorts of elderly (Prospective Investigation of the Vasculature in Uppsala Seniors [PIVUS]: n=977; 50% women, mean age=70.1 years, 71 fatal/nonfatal ischemic stroke events during 10.0 years; and Uppsala Longitudinal Study in Adult Men [ULSAM]: n=720, mean age=77.5 years, 75 ischemic stroke events during 9.5 years). The proteomics chip uses 2 antibodies for each protein and a polymerase chain reaction step to achieve a high-specific binding and the possibility to measure multiple proteins in parallel, but gives no absolute concentrations.

RESULTS

In PIVUS, 16 proteins were related to incident ischemic stroke using a false discovery rate of 5%. Of these, N-terminal pro-B-type natriuretic peptide (P=0.0032), adrenomedullin (P=0.018), and eosinophil cationic protein (P=0.0071) were replicated in ULSAM after adjustment for established stroke risk factors. In predefined secondary meta-analyses of individual data, interleukin-27 subunit α, growth/differentiation factor 15, urokinase plasminogen activator surface receptor, tumor necrosis factor receptor superfamily member 6, macrophage colony-stimulating factor 1, and matrix metalloproteinase-7 were also potential risk markers for ischemic stroke after adjustment for multiple comparisons (P<0.0006). The addition of N-terminal pro-B-type natriuretic peptide, adrenomedullin, and eosinophil cationic protein to a model with established risk factors increased the C-statistic from 0.629 to 0.689 (P=0.001).

CONCLUSIONS

Our data suggest that large-scale proteomics analysis is a promising way of discovering novel biomarkers that could substantially improve the prediction of ischemic stroke.

[Flow mediated vasodilation in overweight children]

INTRODUCTION

Present knowledge suggests that cardiovascular disease originates and progresses from childhood and adolescence. Endothelial dysfunction is an early and crucial event in atherosclerosis.

PATIENTS AND METHOD

Prospective study that compares Flow Mediated Vasodilation (FMV) in children with overweight (OWC) and normal weight children. An ultrasound transducer a standard method were used to measure FMD.

RESULTS

The study included 82 children, of whom 49 were cases (OWC) and 33 controls. FMV values ranged from -6 to 56% (x=11.1%) in OW, and from 0 to 29.6% (x=16.6%) in control children (P<.005). Paradoxical vasoconstriction was found in 34.7% in OWC as compared to nil in controls (P<.005). A significant association was found between vasoconstriction and central obesity and hypertension.

CONCLUSION

The results of this study show that FMV is lower in obese compared to normal children; thus they are more likely to have endothelial dysfunction.

Carotid intima-media thickness progression and risk of vascular events in people with diabetes: results from the PROG-IMT collaboration

OBJECTIVE

Carotid intima-media thickness (CIMT) is a marker of subclinical organ damage and predicts cardiovascular disease (CVD) events in the general population. It has also been associated with vascular risk in people with diabetes. However, the association of CIMT change in repeated examinations with subsequent CVD events is uncertain, and its use as a surrogate end point in clinical trials is controversial. We aimed at determining the relation of CIMT change to CVD events in people with diabetes.

RESEARCH DESIGN AND METHODS

In a comprehensive meta-analysis of individual participant data, we collated data from 3,902 adults (age 33-92 years) with type 2 diabetes from 21 population-based cohorts. We calculated the hazard ratio (HR) per standard deviation (SD) difference in mean common carotid artery intima-media thickness (CCA-IMT) or in CCA-IMT progression, both calculated from two examinations on average 3.6 years apart, for each cohort, and combined the estimates with random-effects meta-analysis.

RESULTS

Average mean CCA-IMT ranged from 0.72 to 0.97 mm across cohorts in people with diabetes. The HR of CVD events was 1.22 (95% CI 1.12-1.33) per SD difference in mean CCA-IMT, after adjustment for age, sex, and cardiometabolic risk factors. Average mean CCA-IMT progression in people with diabetes ranged between -0.09 and 0.04 mm/year. The HR per SD difference in mean CCA-IMT progression was 0.99 (0.91-1.08).

CONCLUSIONS

Despite reproducing the association between CIMT level and vascular risk in subjects with diabetes, we did not find an association between CIMT change and vascular risk. These results do not support the use of CIMT progression as a surrogate end point in clinical trials in people with diabetes.

Shared Neuropathological Characteristics of Obesity, Type 2 Diabetes and Alzheimer's Disease: Impacts on Cognitive Decline

In the past few decades, the prevalence of obesity and type 2 diabetes mellitus (T2DM), as well as older individuals at risk for Alzheimer’s disease (AD), has increased. While the consumption of diets high in fat (total and saturated) have been linked to increased risk of AD, diets rich in antioxidants, polyunsaturated fats, and omega-3 fatty acids are associated with decreased risk. Additionally, AD patients are at increased risk for developing T2DM. Recent research suggests that there are stronger similarities between AD and T2DM than have previously been considered. Here we review the neurocognitive and inflammatory effects of high-fat diet consumption, its relationship to AD, and the treatment potential of dietary interventions that may decrease risk of cognitive decline and other associated neuropathological changes, such as insulin resistance, oxidative stress, and chronic inflammatory processes.

Perfluoroalkyl substances (PFAS) including structural PFOS isomers in plasma from elderly men and women from Sweden: Results from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS)

Per- and polyfluoroalkyl substances (PFASs) are a class of compounds with unique chemical properties that have been shown useful in a wide variety of applications because they provide materials with reduced surface tension and exceptional non-stick properties. PFASs are commonly found in impregnation materials, coatings of papers and textiles, fire-fighting foams, pesticides, and cleaning agents. The potential for human exposure to PFASs is high because of their widespread distribution. The aim of this study was to investigate levels of PFASs in men and women from Sweden and to assess the influence of gender and parity among women. Levels of 13 PFASs were determined in plasma samples collected during 2001-2004 from 1016 (507 women) 70year-old participants from the population-based Prospective Study of the Vasculature in Uppsala Seniors (PIVUS). The PFASs studied were nine perfluorinated carboxylic acids (PFCAs), four perfluorinated sulfonic acids (PFSAs) and perfluorooctane sulfonamide (PFOSA). In addition, structural isomers of perfluorooctane sulfonic acid (PFOS) were determined in a subset of 398 individuals. The detection rates were high and the majority of the studied compounds were detected in more than 75% of the participants. Levels of the selected analytes were found to be similar to other studies of non-occupationally exposed populations. Gender differences were observed in levels of PFHpA which was higher in men, while PFHxS was higher in women. Parity among women was shown to have a minor effect on PFAS concentrations and we found primi- and multiparous women to have slightly lower levels of PFUnDA when compared to nulliparous women.

Soluble Tumor Necrosis Factor Receptor 1 Is Associated with Glomerular Filtration Rate Progression and Incidence of Chronic Kidney Disease in Two Community-Based Cohorts of Elderly Individuals

OBJECTIVE

We aimed to explore and validate the longitudinal associations between soluble tumor necrosis factor receptor 1 (sTNFR1), glomerular filtration rate (GFR) progression, and chronic kidney disease (CKD) incidence in two independent community-based cohorts of elderly individuals with prespecified subgroup analyses in individuals without prevalent diabetes.

RESEARCH DESIGN AND METHODS

Two community-based cohorts of elderly individuals were used with 5-year follow-up data on estimated GFR: the Uppsala Longitudinal Study of Adult Men (ULSAM; n = 437 men; mean age: 78 years) and the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS; n = 703; mean age: 70 years; 51% women). GFR categories were defined as ≥60, 30-60, and <30 ml/min/1.73 m(2).

RESULTS

In longitudinal multivariable logistic regression models adjusted for inflammatory markers and established cardiovascular risk factors, higher serum sTNFR1 was significantly associated with an increased risk to progress to a lower GFR category in both ULSAM and PIVUS [odds ratio (OR) per standard deviation (SD) increase 1.28 (95% CI 1.03-1.60) and OR 1.56 (95% CI 1.30-1.87), respectively]. Also, in subgroup analyses in individuals with a GFR ≥60 ml/min/1.73 m(2) at baseline, higher sTNFRs were associated with incident CKD after 5 years in both cohorts [ULSAM: OR per SD increase 1.49 (95% CI 1.16-1.9) and PIVUS: OR 1.84 (95% CI 1.50-2.26)]. Associations were similar in individuals without diabetes.

CONCLUSIONS

Higher circulating sTNFR1 independently predicts the progression to a worse GFR category and CKD incidence in elderly individuals even in the absence of diabetes. Further studies are warranted to investigate the underlying mechanisms, and to evaluate the clinical relevance of our findings.

Genome-wide association study of plasma levels of polychlorinated biphenyls disclose an association with the CYP2B6 gene in a population-based sample

BACKGROUND

Polychlorinated biphenyls (PCBs) are a group of man-made environmental pollutants which accumulate in humans with adverse health effects. To date, very little effort has been devoted to the study of the metabolism of PCBs on a genome-wide level.

OBJECTIVES

Here, we conducted a genome-wide association study (GWAS) to identify genomic regions involved in the metabolism of PCBs.

METHODS

Plasma levels of 16 PCBs ascertained in a cohort of elderly individuals from Sweden (n=1016) were measured using gas chromatography-high resolution mass spectrophotometry (GC-HRMS). DNA samples were genotyped on the Infinium Omni Express bead microarray, and imputed up to reference panels from the 1000 Genomes Project. Association testing was performed in a linear regression framework under an additive model.

RESULTS

Plasma levels of PCB-99 demonstrated genome-wide significant association with single nucleotide polymorphisms (SNPs) mapping to chromosome 19q13.2. The SNP with the strongest association was rs8109848 (p=3.7×10(-13)), mapping to an intronic region of CYP2B6. Moreover, when all PCBs were conditioned on PCB-99, further signals were revealed for PCBs -74, -105 and -118, mapping to the same genomic region. The lead SNPs were rs8109848 (p=3.8×10(-12)) for PCB-118, rs4802104 (p=1.4×10(-9)) for PCB-74 and rs4803413 (p=2.5×10(-9)) for PCB-105, all of which map to CYP2B6.

CONCLUSIONS

In our study, we found plasma levels of four lower-chlorinated PCBs to be significantly associated with the genetic region mapping to the CYP2B6 locus. These findings show that CYP2B6 is of importance for the metabolism of PCBs in humans, and may help to identify individuals who may be susceptible to PCB toxicity.

Genome-wide association study of toxic metals and trace elements reveals novel associations

The accumulation of toxic metals in the human body is influenced by exposure and mechanisms involved in metabolism, some of which may be under genetic control. This is the first genome-wide association study to investigate variants associated with whole blood levels of a range of toxic metals. Eleven toxic metals and trace elements (aluminium, cadmium, cobalt, copper, chromium, mercury, manganese, molybdenum, nickel, lead and zinc) were assayed in a cohort of 949 individuals using mass spectrometry. DNA samples were genotyped on the Infinium Omni Express bead microarray and imputed up to reference panels from the 1000 Genomes Project. Analyses revealed two regions associated with manganese level at genome-wide significance, mapping to 4q24 and 1q41. The lead single nucleotide polymorphism (SNP) in the 4q24 locus was rs13107325 (P-value = 5.1 × 10⁻¹¹, β = −0.77), located in an exon of SLC39A8, which encodes a protein involved in manganese and zinc transport. The lead SNP in the 1q41 locus is rs1776029 (P-value = 2.2 × 10⁻¹⁴, β = −0.46). The SNP lies within the intronic region of SLC30A10, another transporter protein. Among other metals, the loci 6q14.1 and 3q26.32 were associated with cadmium and mercury levels (P = 1.4 × 10⁻¹⁰, β = −1.2 and P = 1.8 × 10⁻⁹, β = −1.8, respectively). Whole blood measurements of toxic metals are associated with genetic variants in metal transporter genes and others. This is relevant in inferring metabolic pathways of metals and identifying subsets of individuals who may be more susceptible to metal toxicity.

Profound parental bias associated with chromosome 14 acquired uniparental disomy indicates targeting of an imprinted locus

Acquired uniparental disomy (aUPD) is a common finding in myeloid malignancies and typically acts to convert a somatically acquired heterozygous mutation to homozygosity. We sought to identify the target of chromosome 14 aUPD (aUPD14), a recurrent abnormality in myeloid neoplasms and population cohorts of elderly individuals. We identified 29 cases with aUPD14q that defined a minimal affected region (MAR) of 11.2 Mb running from 14q32.12 to the telomere. Exome sequencing (n=7) did not identify recurrently mutated genes, but methylation-specific PCR at the imprinted MEG3-DLK1 locus located within the MAR demonstrated loss of maternal chromosome 14 and gain of paternal chromosome 14 (P<0.0001), with the degree of methylation imbalance correlating with the level of aUPD (r=0.76; P=0.0001). The absence of driver gene mutations in the exomes of three individuals with aUPD14q but no known haematological disorder suggests that aUPD14q may be sufficient to drive clonal haemopoiesis. Analysis of cases with both aUPD14q and JAK2 V617F (n=11) indicated that aUPD14q may be an early event in some cases but a late event in others. We conclude that aUPD14q is a recurrent abnormality that targets an imprinted locus and may promote clonal haemopoiesis either as an initiating event or as a secondary change.

Cardiac troponin I levels in an elderly population from the community--The implications of sex

OBJECTIVES

The importance of sex on cardiac troponin levels is increasingly recognized. We investigated whether the entities associated with troponin leakage and the prognostic consequences thereof would differ between elderly men and women from the community.

DESIGN AND METHODS

Cardiac troponin I (cTnI) levels were measured using a high-sensitivity assay (Abbott Laboratories) in 70-year old men (n = 502) and women (n = 502) from the PIVUS study. All study participants were followed up for 10 years regarding all-cause mortality and incident cardiovascular (CV) disease.

RESULTS

Median cTnI levels were 4.1 and 3.0 ng/L in men and women, respectively (p<0.001). By multiple linear regression, the relative contribution of lower left-ventricular ejection fraction and ischemic ECG changes to cTnI levels was greater in men compared to women. For other clinical and echocardiographic variables, similar associations were found. cTnI independently predicted all-cause mortality in men (n = 93 [18.5%]; hazard ratio [HR] 1.38 [1.12-1.70]) and women (n = 62 [12.4%]; HR 1.59 [1.11-2.28]) but not incident CV disease in subjects being CV healthy at baseline (n = 163/857). The interaction terms of sex on the associations of cTnI with both outcomes were non-significant. Sex-specific cut-offs did not improve prognostication. Variations in the pattern of entities associated with cTnI leakage had no impact on event rates.

CONCLUSIONS

We found some differences in the entities associated with higher cTnI levels in elderly community-dwelling men and women. However, this did not translate into differences in the associations of cTnI with adverse outcome.

Intracranial volume normalization methods: considerations when investigating gender differences in regional brain volume

Intracranial volume (ICV) normalization of regional brain volumes (v) is common practice in volumetric studies of the aging brain. Multiple normalization methods exist and this study aimed to investigate when each method is appropriate to use in gender dimorphism studies and how differences in v are affected by the choice of method. A new method based on weighted ICV matching is also presented. Theoretical reasoning and simulated experiments were followed by an evaluation using real data comprising 400 subjects, all 75 years old, whose ICV was segmented with a gold standard method. The presented method allows good visualization of volume relation between gender groups. A different gender dimorphism in volume was found depending on the normalization method used for both simulated and real data. Method performance was also seen to depend on the slope (B) and intercept (m) from the linear relation between v and ICV (v=B·ICV+m) as well as gender distribution in the cohort. A suggested work-flow for selecting ICV normalization method when investigating gender related differences in regional brain volume is presented.

No Evidence of a Causal Relationship between Plasma Homocysteine and Type 2 Diabetes: A Mendelian Randomization Study

Background: Several observational studies have shown an association between increased circulating homocysteine and risk of type 2 diabetes (T2D). We aimed to assess whether this relation is causal using genetic data from large populations of individuals of European descent.

Methods: We investigated the association between homocysteine concentrations and blood glucose, plasma insulin, T2D in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) cohort (n = 1,016). A score of five previously published single nucleotide polymorphisms (SNPs) from genes involved in homocysteine metabolism were utilized as genetic instrument for homocysteine concentrations. The effect estimate of this genetic score with T2D was determined using results from the DIAbetes Genetics Replication And Meta-analysis (DIAGRAM) consortium (including 34,840 cases and 114,981 controls). Further, the effects of the genetic score with fasting glucose and insulin were determined using results from the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC) (up to 38,238 non-diabetic participants).

Results: The genetic score provided a strong instrument for homocysteine concentrations (P = 2.7 × 10⁻¹⁴³, F = 650). In the PIVUS cohort, we found an association of homocysteine with fasting insulin [β = 0.056 (95% CI 0.021, 0.090), P = 0.001], but not with incident diabetes. We did not find any evidence of a causal effect of homocysteine on fasting glucose, fasting insulin, or T2D (P > 0.05 for all analyses) when using data from DIAGRAM or MAGIC studies.

Conclusion: No evidence of a causal relationship of levels of plasma homocysteine with fasting glucose, fasting insulin, or T2D was observed.

Saturation diving; physiology and pathophysiology

In saturation diving, divers stay under pressure until most of their tissues are saturated with breathing gas. Divers spend a long time in isolation exposed to increased partial pressure of oxygen, potentially toxic gases, bacteria, and bubble formation during decompression combined with shift work and long periods of relative inactivity. Hyperoxia may lead to the production of reactive oxygen species (ROS) that interact with cell structures, causing damage to proteins, lipids, and nucleic acid. Vascular gas-bubble formation and hyperoxia may lead to dysfunction of the endothelium. The antioxidant status of the diver is an important mechanism in the protection against injury and is influenced both by diet and genetic factors. The factors mentioned above may lead to production of heat shock proteins (HSP) that also may have a negative effect on endothelial function. On the other hand, there is a great deal of evidence that HSPs may also have a "conditioning" effect, thus protecting against injury. As people age, their ability to produce antioxidants decreases. We do not currently know the capacity for antioxidant defense, but it is reasonable to assume that it has a limit. Many studies have linked ROS to disease states such as cancer, insulin resistance, diabetes mellitus, cardiovascular diseases, and atherosclerosis as well as to old age. However, ROS are also involved in a number of protective mechanisms, for instance immune defense, antibacterial action, vascular tone, and signal transduction. Low-grade oxidative stress can increase antioxidant production. While under pressure, divers change depth frequently. After such changes and at the end of the dive, divers must follow procedures to decompress safely. Decompression sickness (DCS) used to be one of the major causes of injury in saturation diving. Improved decompression procedures have significantly reduced the number of reported incidents; however, data indicate considerable underreporting of injuries. Furthermore, divers who are required to return to the surface quickly are under higher risk of serious injury as no adequate decompression procedures for such situations are available. Decompression also leads to the production of endothelial microparticles that may reduce endothelial function. As good endothelial function is a documented indicator of health that can be influenced by regular exercise, regular physical exercise is recommended for saturation divers. Nowadays, saturation diving is a reasonably safe and well controlled method for working under water. Until now, no long-term impact on health due to diving has been documented. However, we still have limited knowledge about the pathophysiologic mechanisms involved. In particular we know little about the effect of long exposure to hyperoxia and microparticles on the endothelium.

Circulating levels of environmental contaminants are associated with dietary patterns in older adults

BACKGROUND

Food intake contributes substantially to our exposure to environmental contaminants. Still, little is known about our dietary habits' contribution to exposure variability.

OBJECTIVE

The aim of this study was to assess circulating levels of environmental contaminants in relation to predefined dietary patterns in an elderly Swedish population.

METHODS

Dietary data and serum concentrations of environmental contaminants were obtained from 844 70-year-old Swedish subjects (50% women) in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Dietary data from 7-day food records was used to assess adherence to a Mediterranean-like diet, a low carbohydrate-high protein diet and the WHO dietary recommendations. Circulating levels of 6 polychlorinated biphenyl markers, 3 organochlorine pesticides, 1 dioxin and 1 polybrominated diphenyl ether, the metals cadmium, lead, mercury and aluminum and serum levels of bisphenol A and 4 phthalate metabolites were investigated in relation to dietary patterns in multivariate linear regression models.

RESULTS

A Mediterranean-like diet was positively associated with levels of several polychlorinated biphenyls (118, 126, 153, and 209), trans-nonachlor and mercury. A low carbohydrate-high protein diet was positively associated with polychlorinated biphenyls 118 and 153, trans-nonachlor, hexachlorobenzene and p, p'-dichlorodiphenyldichloroethylene, mercury and lead. The WHO recommended diet was negatively related to levels of dioxin and lead, and borderline positively to polychlorinated biphenyl 118 and trans-nonachlor.

CONCLUSION

Dietary patterns were associated in diverse manners with circulating levels of environmental contaminants in this elderly Swedish population. Following the WHO dietary recommendations seems to be associated with a lower burden of environmental contaminants.

Interleukin-8 is associated with increased total mortality in women but not in men-findings from a community-based cohort of elderly

OBJECTIVE

To elucidate the association among circulating IL-8 and total mortality in a cohort of elderly, and to explore potential sex differences in the observed association.

METHODS

The Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) is a cohort of 70-year-old men and women living in Uppsala, Sweden; baseline period: 2001-2004. IL-8 serum measurements were performed in 1003 participants.

RESULTS

In total, 61 men and 40 women died during follow-up (median 7.9 years). Baseline IL-8 concentrations were higher in women than in men (P = 0.03). In a multivariable model adjusting for age, established cardiovascular risk factors, and C-reactive protein, log-transformed standard deviation increments in IL-8 levels were weakly associated with an increased risk for total mortality (hazard ratio (HR) 1.12, 95% confidence interval (CI) 1.02-1.23, P < 0.05) in the whole cohort. Stratified analysis revealed an association in women (HR 1.18, 95% CI 1.06-1.30, P < 0.01) but not in men (HR 0.98, 95% CI 0.76-1.26).

CONCLUSIONS

A weak association between IL-8 serum levels and an increased risk for mortality was observed. The prospective data support the role of IL-8 as a biomarker of interest; yet, further studies are warranted to elucidate validity of our finding and the possibility of a sex difference.

Duffy antigen receptor genetic variant and the association with Interleukin 8 levels

The aim of this study is to identify loci associated with circulating levels of Interleukin 8 (IL8). We investigated the associations of 121,445 single nucleotide polymorphisms (SNPs) from the Illumina 200K CardioMetabochip with IL8 levels in 1077 controls from the Stockholm Heart Epidemiology Program (SHEEP) study, using linear regression under an additive model of inheritance. Five SNPs (rs12075A/G, rs13179413C/T, rs6907989T/A, rs9352745A/C, rs1779553T/C) reached the pre-defined threshold of genome-wide significance (p<1.0×10(-5)) and were tested for in silico replication in three independent populations, derived from the PIVUS, MDC-CC and SCARF studies. IL8 was measured in serum (SHEEP, PIVUS) and plasma (MDC-CC, SCARF). The strongest association was found with the SNP rs12075 A/G, Asp42Gly (p=1.6×10(-6)), mapping to the Duffy antigen receptor for chemokines (DARC) gene on chromosome 1. The minor allele G was associated with 15.6% and 10.4% reduction in serum IL8 per copy of the allele in SHEEP and PIVUS studies respectively. No association was observed between rs12075 and plasma IL8.

CONCLUSION

rs12075 was associated with serum levels but not with plasma levels of IL8. It is likely that serum IL8 represents the combination of levels of circulating plasma IL8 and additional chemokine liberated from the erythrocyte DARC reservoir due to clotting. These findings highlight the importance of understanding IL8 as a biomarker in cardiometabolic diseases.

Mutagenesis. Smoking is associated with mosaic loss of chromosome Y

Tobacco smoking is a risk factor for numerous disorders, including cancers affecting organs outside the respiratory tract. Epidemiological data suggest that smoking is a greater risk factor for these cancers in males compared with females. This observation, together with the fact that males have a higher incidence of and mortality from most non-sex-specific cancers, remains unexplained. Loss of chromosome Y (LOY) in blood cells is associated with increased risk of nonhematological tumors. We demonstrate here that smoking is associated with LOY in blood cells in three independent cohorts [TwinGene: odds ratio (OR) = 4.3, 95% confidence interval (CI) = 2.8 to 6.7; Uppsala Longitudinal Study of Adult Men: OR = 2.4, 95% CI = 1.6 to 3.6; and Prospective Investigation of the Vasculature in Uppsala Seniors: OR = 3.5, 95% CI = 1.4 to 8.4] encompassing a total of 6014 men. The data also suggest that smoking has a transient and dose-dependent mutagenic effect on LOY status. The finding that smoking induces LOY thus links a preventable risk factor with the most common acquired human mutation.

Large-scale metabolomic profiling identifies novel biomarkers for incident coronary heart disease

Analyses of circulating metabolites in large prospective epidemiological studies could lead to improved prediction and better biological understanding of coronary heart disease (CHD). We performed a mass spectrometry-based non-targeted metabolomics study for association with incident CHD events in 1,028 individuals (131 events; 10 y. median follow-up) with validation in 1,670 individuals (282 events; 3.9 y. median follow-up). Four metabolites were replicated and independent of main cardiovascular risk factors [lysophosphatidylcholine 18∶1 (hazard ratio [HR] per standard deviation [SD] increment = 0.77, P-value<0.001), lysophosphatidylcholine 18∶2 (HR = 0.81, P-value<0.001), monoglyceride 18∶2 (MG 18∶2; HR = 1.18, P-value = 0.011) and sphingomyelin 28∶1 (HR = 0.85, P-value = 0.015)]. Together they contributed to moderate improvements in discrimination and re-classification in addition to traditional risk factors (C-statistic: 0.76 vs. 0.75; NRI: 9.2%). MG 18∶2 was associated with CHD independently of triglycerides. Lysophosphatidylcholines were negatively associated with body mass index, C-reactive protein and with less evidence of subclinical cardiovascular disease in additional 970 participants; a reverse pattern was observed for MG 18∶2. MG 18∶2 showed an enrichment (P-value = 0.002) of significant associations with CHD-associated SNPs (P-value = 1.2×10⁻⁷ for association with rs964184 in the ZNF259/APOA5 region) and a weak, but positive causal effect (odds ratio = 1.05 per SD increment in MG 18∶2, P-value = 0.05) on CHD, as suggested by Mendelian randomization analysis. In conclusion, we identified four lipid-related metabolites with evidence for clinical utility, as well as a causal role in CHD development.

Non-targeted metabolomic profiling of large population-based studies has become feasible only in the past 1–2 years and this hypothesis-free exploration of the metabolome holds a great potential to fuel the discovery of novel biomarkers for coronary heart disease (CHD). Such biomarkers are not only important for risk stratification and treatment decisions, but can also improve understanding of cardiovascular disease pathophysiology to identify new drug targets. In this study, we investigated the metabolic profiles of more than 3,600 individuals from three population-based studies, and discovered four metabolites that are consistently associated with incident CHD. We integrate genetic and metabolomic analysis to delineate the underlying biological mechanisms and evaluate potential causal effects of the novel biomarkers. Specifically, we found one metabolite to be strongly associated with single nucleotides polymorphisms previously reported for association with CHD, and consistent with a potential causal role in CHD development, as suggested by Mendelian randomization analysis.

Effect of acute hypobaric hypoxia on the endothelial glycocalyx and digital reactive hyperemia in humans

Introduction: Hypoxia is associated with increased capillary permeability. This study tested whether acute hypobaric hypoxia involves degradation of the endothelial glycocalyx.

Methods: We exposed 12 subjects to acute hypobaric hypoxia (equivalent to 4500 m for 2–4 h) and measured venous blood concentrations of biomarkers reflecting endothelial and glycocalyx degradation (catecholamines, syndecan-1, soluble CD40 ligand, protein C, soluble thrombomodulin, tissue-type plasminogen activators, histone-complexed DNA fragments, and nitrite/nitrate). Endothelial function was assessed by the hyperemic response to brachial artery occlusion by peripheral arterial tonometry.

Results: Compared with normoxic baseline levels, hypoxia increased concentrations of syndecan-1 from 22 (95% confidence interval: 17–27) to 25 (19–30) ng/ml (p < 0.02) and protein C from 76 (70–83)% to 81 (74–88)% (p < 0.02). Nitrite/nitrate decreased from 23 (18–27) μM at baseline to 19 (14–24) μM and 18 (14–21) μM in hypoxia and recovery, respectively (p < 0.05). Other biomarkers remained unchanged. The post-occlusion/pre-occlusion ratio (reactive hyperemia index, RHI) decreased from 1.80 (1.52–2.07) in normoxia to 1.62 (1.28–1.96) after 2–4 h of hypobaric hypoxia and thereafter increased to 2.43 (1.99–2.86) during normoxic recovery (p < 0.01).

Conclusions: The increase in syndecan-1 and protein C suggests that acute hypobaric hypoxia produces a minor degree of glycocalyx degradation and overall cellular damage. After hypoxia RHI rebounded to higher than baseline levels suggesting improved endothelial functionality.

Endostatin level is associated with kidney injury in the elderly: findings from two community-based cohorts

BACKGROUND

We aimed to investigate the associations between circulating endostatin and the different aspects of renal dysfunction, namely, estimated (cystatin C) glomerular filtration rate (GFR) and urine albumin-creatinine ratio (ACR).

METHODS

Two independent longitudinal community-based cohorts of elderly. ULSAM, n = 786 men; age 78 years; median GFR 74 ml/min/1.73 m(2); median ACR 0.80 mg/mmol); and PIVUS, n = 815; age 75 years; 51% women; median GFR; 67 ml/min/1.73 m(2); median ACR 1.39 mg/mmol. Cross-sectional associations between the endostatin levels and GFR as well as ACR, and longitudinal association between endostatin at baseline and incident CKD (defined as GFR <60 ml/min/1.73 m(2)) were assessed.

RESULTS

In cross-sectional regression analyses adjusting for age, gender, inflammation, and cardiovascular risk factors, serum endostatin was negatively associated with GFR (ULSAM: B-coefficient per SD increase -0.51, 95% CI (-0.57, -0.45), p < 0.001; PIVUS -0.47, 95% CI (-0.54, -0.41), p < 0.001) and positively associated with ACR (ULSAM: B-coefficient per SD increase 0.24, 95% CI (0.15, 0.32), p < 0.001; PIVUS 0.13, 95% CI (0.06-0.20), p < 0.001) in both cohorts. Moreover, in longitudinal multivariable analyses, higher endostatin levels were associated with increased risk for incident CKD defined as GFR <60 ml/min/1.73 m(2) at re-investigations in both ULSAM (odds ratio per SD increase of endostatin 1.39 (95% CI 1.01-1.90) and PIVUS 1.68 (95% CI 1.36-2.07)).

CONCLUSIONS

Higher circulating endostatin is associated with lower GFR and higher albuminuria and independently predicts incident CKD in elderly subjects. Further studies are warranted to investigate the underlying mechanisms linking endostatin to kidney pathology, and to evaluate the clinical relevance of our findings.

Influence of persistent organic pollutants on oxidative stress in population-based samples

Persistent organic pollutants (POPs) are a large group of chemicals widely used and produced in various industrial applications. Many cell culture/animal studies have shown that POPs can induce oxidative stress. Since such data is lacking in humans, we conducted a large population-based study to analyze associations between POPs and oxidative stress markers. We measured following POPs; 16 polychlorinated biphenyls (PCBs), 5 organochlorine (OC) pesticides, octachlorinated dibenzo-p-dioxin, and polybrominated diphenyl ether 47, and oxidative stress markers; homocysteine, reduced [GSH] and oxidized glutathione [GSSG], glutathione ratio [GSSG/GSH], total glutathione, oxidized low-density lipoprotein [ox-LDL], ox-LDL antibodies, conjugated dienes, baseline conjugated dienes of LDL, and total anti-oxidative capacity in plasma samples collected from 992 70-year old individuals (50% women) from the population-based Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) cohort. Linear regression analyses were performed to study the associations between oxidative stress markers and summary measures of POPs including the total toxic equivalence (TEQ), sums of PCBs and OC pesticides (main exposures) while adjusting for potential confounders. In multivariable-adjusted analyses, sum of PCBs showed strong associations with ox-LDL (β=0.94; P=2.9*10(-6)). Further, sum of PCBs showed association with glutathione-related markers (GSSG: β=-0.01; P=6.0*10(-7); GSSG/GSH: β=-0.002; P=9.7*10(-10)), although in reverse direction. Other summary measures did not show any significant association with these markers. In our study of elderly individuals from the general population, we show that plasma levels of POPs are associated with markers of increased oxidative stress thereby suggesting that even low dose background exposure to POPs may be involved in oxidative stress.

Fat mass and obesity-associated gene (FTO) is linked to higher plasma levels of the hunger hormone ghrelin and lower serum levels of the satiety hormone leptin in older adults

The mechanisms through which common polymorphisms in the fat mass and obesity-associated gene (FTO) drive the development of obesity in humans are poorly understood. Using cross-sectional data from 985 older people (50% females) who participated at age 70 years in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS), circulating levels of ghrelin and leptin were measured after an overnight fast. In addition, subjects were genotyped for FTO rs17817449 (AA, n = 345 [35%]; AC/CA, n = 481 [48.8%]; CC, n = 159 [16.1%]). Linear regression analyses controlling for sex, self-reported physical activity level, fasting plasma glucose, and BMI were used. A positive relationship between the number of FTO C risk alleles and plasma ghrelin levels was found (P = 0.005; relative plasma ghrelin difference between CC and AA carriers = ∼ 9%). In contrast, serum levels of the satiety-enhancing hormone leptin were inversely linked to the number of FTO C risk alleles (P = 0.001; relative serum leptin difference between CC and AA carriers = ∼ 11%). These associations were also found when controlling for waist circumference. The present findings suggest that FTO may facilitate weight gain in humans by shifting the endocrine balance from the satiety hormone leptin toward the hunger-promoting hormone ghrelin.