Plasma levels of adrenomedullin and atrial and brain natriuretic peptides in the general population: their relations to age and pulse pressure

Health-related quality of life and DNA methylation-based aging biomarkers among survivors of childhood cancer

BACKGROUND

Childhood cancer survivors are at high risk for morbidity and mortality and poor patient-reported outcomes, typically health-related quality of life (HRQOL). However, associations between DNA methylation-based aging biomarkers and HRQOL have not been evaluated.

METHODS

DNA methylation was generated with Infinium EPIC BeadChip on blood-derived DNA (median for age at blood draw = 34.5 years, range = 18.5-66.6 years), and HRQOL was assessed with age at survey (mean = 32.3 years, range = 18.4-64.5 years) from 2206 survivors in the St Jude Lifetime Cohort. DNA methylation-based aging biomarkers, including epigenetic age using multiple clocks (eg, GrimAge) and others (eg, DNAmB2M: beta-2-microglobulin; DNAmADM: adrenomedullin), were derived from the DNAm Age Calculator (https://dnamage.genetics.ucla.edu). HRQOL was assessed using the Medical Outcomes Study 36-Item Short-Form Health Survey to capture 8 domains and physical and mental component summaries. General linear models evaluated associations between HRQOL and epigenetic age acceleration (EAA; eg, EAA_GrimAge) or other age-adjusted DNA methylation-based biomarkers (eg, ageadj_DNAmB2M) after adjusting for age at blood draw, sex, cancer treatments, and DNA methylation-based surrogate for smoking pack-years. All P values were 2-sided.

RESULTS

Worse HRQOL was associated with greater EAA_GrimAge (physical component summaries: β = -0.18 years, 95% confidence interval [CI] = -0.251 to -0.11 years; P = 1.85 × 10-5; and 4 individual HRQOL domains), followed by ageadj_DNAmB2M (physical component summaries: β = -0.08 years, 95% CI = -0.124 to -0.037 years; P = .003; and 3 individual HRQOL domains) and ageadj_DNAmADM (physical component summaries: β = -0.082 years, 95% CI = -0.125 to -0.039 years; P = .002; and 2 HRQOL domains). EAA_Hannum (Hannum clock) was not associated with any HRQOL.

CONCLUSIONS

Overall and domain-specific measures of HRQOL are associated with DNA methylation measures of biological aging. Future longitudinal studies should test biological aging as a potential mechanism underlying the association between poor HRQOL and increased risk of clinically assessed adverse health outcomes.

Modulation of neural gene networks by estradiol in old rhesus macaque females

The postmenopausal decrease in circulating estradiol (E2) levels has been shown to contribute to several adverse physiological and psychiatric effects. To elucidate the molecular effects of E2 on the brain, we examined differential gene expression and DNA methylation (DNAm) patterns in the nonhuman primate brain following ovariectomy (Ov) and subsequent subcutaneous bioidentical E2 chronic treatment. We identified several dysregulated molecular networks, including MAPK signaling and dopaminergic synapse response, that are associated with ovariectomy and shared across two different brain areas, the occipital cortex (OC) and prefrontal cortex (PFC). The finding that hypomethylation (p = 1.6 × 10-51) and upregulation (p = 3.8 × 10-3) of UBE2M across both brain regions provide strong evidence for molecular differences in the brain induced by E2 depletion. Additionally, differential expression (p = 1.9 × 10-4; interaction p = 3.5 × 10-2) of LTBR in the PFC provides further support for the role E2 plays in the brain, by demonstrating that the regulation of some genes that are altered by ovariectomy may also be modulated by Ov followed by hormone replacement therapy (HRT). These results present real opportunities to understand the specific biological mechanisms that are altered with depleted E2. Given E2's potential role in cognitive decline and neuroinflammation, our findings could lead to the discovery of novel therapeutics to slow cognitive decline. Together, this work represents a major step toward understanding molecular changes in the brain that are caused by ovariectomy and how E2 treatment may revert or protect against the negative neuro-related consequences caused by a depletion in estrogen as women approach menopause.

Impact of adrenomedullin on mitochondrial respiratory capacity in human adipocyte

Mitochondrial function in adipocyte is an important aspect in maintaining metabolic homeostasis. Our previous observation showed that circulating levels of adrenomedullin (ADM) and mRNA and protein for ADM in omental adipose tissue were higher in patients with gestational diabetes mellitus (GDM), and these alterations are accompanied by glucose and lipid metabolic dysregulation, but the impact of ADM on mitochondrial biogenesis and respiration in human adipocyte remain elusive. The present study demonstrated that: (1) Increasing doses of glucose and ADM inhibit human adipocyte mRNA expressions of mitochondrial DNA (mtDNA)-encoded subunits of electron transport chain, including nicotinamide adenine dinucleotide dehydrogenase (ND) 1 and 2, cytochrome (CYT) b, as well as ATPase 6; (2) ADM significantly increases human adipocyte mitochondrial reactive oxygen species generation and this increase is reversed by ADM antagonist, ADM22-52, but treatment with ADM does not significantly affect mitochondrial contents in the adipocytes; (3) Adipocyte basal and maximal oxygen consumption rate are dose-dependently suppressed by ADM, thus results in impaired mitochondrial respiratory capacity. We conclude that elevated ADM observed in diabetic pregnancy may be involved in glucose and lipid dysregulation through compromising adipocyte mitochondrial function, and blockade of ADM action may improve GDM-related glucose and adipose tissue dysfunction.

Impact of Adrenomedullin on Mitochondrial Respiratory Capacity in Human Adipocyte

For metabolic homeostasis adequate mitochondrial function in adipocytes is essential. Our previous observation showed that circulating levels of adrenomedullin (ADM) and mRNA and protein for ADM in omental adipose tissue were higher in patients with gestational diabetes mellitus (GDM) compared with normal pregnancy, and these alterations are accompanied by glucose and lipid metabolic dysregulation, but the impact of ADM on mitochondrial biogenesis and respiration in human adipocyte remain elusive. In this study we demonstrated that: (1) Increasing doses of glucose and ADM inhibit human adipocyte mRNA expressions of mitochondrial DNA (mtDNA)-encoded subunits of electron transport chain (ETC), including nicotinamide adenine dinucleotide dehydrogenase (ND) 1 and 2, cytochrome (CYT) b, as well as ATPase 6; (2) ADM significantly increases human adipocyte mitochondrial reactive oxygen species (ROS) generation and this increase is reversed by ADM antagonist, ADM22-52, but does not significantly affect adipocyte mitochondrial contents; (3) Adipocyte basal and maximal oxygen consumption rate (OCR) are dose-dependently suppressed by ADM, and results in impaired mitochondrial respiratory capacity. We conclude that elevatedADM observed in diabetic pregnancy may be involved in glucose and lipid dysregulation through compromising adipocyte mitochondrial function, and blockade of ADM actions in adipocytes may improve GDM-related metabolic complications.

Endogenous Vasoactive Peptides and Vascular Aging-Related Diseases

Vascular aging is a specific type of organic aging that plays a central role in the morbidity and mortality of cardiovascular and cerebrovascular diseases among the elderly. It is essential to develop novel interventions to prevent/delay age-related vascular pathologies by targeting fundamental cellular and molecular aging processes. Endogenous vasoactive peptides are compounds formed by a group of amino acids connected by peptide chains that exert regulatory roles in intercellular interactions involved in a variety of biological and pathological processes. Emerging evidence suggests that a variety of vasoactive peptides play important roles in the occurrence and development of vascular aging and related diseases such as atherosclerosis, hypertension, vascular calcification, abdominal aortic aneurysms, and stroke. This review will summarize the cumulative roles and mechanisms of several important endogenous vasoactive peptides in vascular aging and vascular aging-related diseases. In addition, we also aim to explore the promising diagnostic function as biomarkers and the potential therapeutic application of endogenous vasoactive peptides in vascular aging-related diseases.

Lipid dysfunction and adrenomedullin expression in omental versus subcutaneous adipose tissues in diabetic pregnancies

Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy but the underlying mechanism remains obscure. The aims of this study are to examine if omental adipose tissue (OMAT) and subcutaneous AT (SCAT) differentially express proinflammatory and lipid metabolic adipokines, and if so, whether their regional differences have implications on lipid metabolism in GDM. Paired samples of OMAT and SCAT were excised from pregnant women in scheduled Cesarean sections with non-obese (NOBS), obese (OBS) and GDM. The results showed that the mRNA of monocyte chemoattractant protein (MCP)-1, macrophage marker CD68, and cytokines IL-6, IL-8, and TNF-α are increased in OMAT from GDM women compared to that in NOBS and OBS women (P<0.05). Glucose and TNF-α dose-dependently enhanced ADM and its receptor components CRLR and RAMPs in human adipocytes. Immunofluorescence showed that ADM and its receptor components are higher in OMAT from GDM women compared to non-GDM women. Further, basal lipolysis was greater in OMAT than in SCAT and ADM stimulates further glycerol release in OMAT, but not in SCAT, and these increases are reduced by ADM antagonist, ADM22-52. We therefore conclude that elevated ADM and its receptor expressions by OMAT, but not by SCAT appear to contribute to the lipid dysregulation in GDM women, and manipulation of ADM may represent one of the novel approaches in minimizing the risk of GDM-related fetal overgrowth.

Adrenomedullin and its receptors are expressed in mouse pancreatic β-cells and suppresses insulin synthesis and secretion

Gestational diabetes mellitus (GDM) is associated with defective pancreatic β-cell adaptation in pregnancy, but the underlying mechanism remains obscure. Our previous studies demonstrated that GDM women display increased plasma adrenomedullin (ADM) levels, and non-obese GDM mice show decreased serum concentrations of insulin and the number of β-cells in pancreas islets. The aims of this study is to examine if ADM and its receptors are expressed in female mouse pancreas, and if so, whether insulin secretion is regulated by ADM in mouse β-cell line, NIT-1 cells and isolated mouse pancreatic islets. Present study shows that ADM and its receptor components CRLR, RAMPs are present in mouse pancreatic islets and co-localized with insulin. The expressions of ADM, CRLR and RAMP2 in islets from pregnant mice are reduced compared to that of non-pregnant mice. NIT-1-β cells express ADM and its receptor mRNA, and glucose dose-dependently stimulates expressions. Furthermore, ADM inhibits NIT-1-β cell growth, and this inhibition is reversed by ADM antagonist, ADM22-52. The glucose-induced insulin secretion was suppressed by ADM in NIT-1-β cells and isolated pancreatic islets from pregnant mice. These inhibitory effects are accompanied by upregulation of endoplasmic reticulum (ER) stress biomarker genes in NIT-1-β cells. This study unveils that reduced ADM and its receptors may play a role in β-cell adaptation during pregnancy, while increased plasma ADM in GDM may contribute to the β-cells dysfunction, and blockade of ADM may reverse β-cell insulin production.

Age-related amyloidosis outside the brain: A state-of-the-art review

Inside and outside the brain, accumulation of amyloid fibrils plays key roles in the pathogenesis of fatal age-related diseases such as Alzheimer's and Parkinson's diseases and wild-type transthyretin amyloidosis. Although the incidence of all amyloidoses increases with age, for some types of amyloidosis aging is known as the main direct risk factor, and these types are typically diseases of elderly people. More than 10 different precursor proteins are known to cause age-associated amyloidosis; these proteins include amyloid β protein, α-synuclein, transthyretin, islet amyloid polypeptide, atrial natriuretic factor, and the newly discovered epidermal growth factor-containing fibulin-like extracellular matrix protein 1. Except for intracerebral amyloidoses, most age-related amyloidoses have been little studied. Indeed, in view of the increasing life expectancy in our societies, understanding how aging is involved in the process of amyloid fibril accumulation and the effects of amyloid deposits on the aging body is extremely important. In this review, we summarize current knowledge about the nature of amyloid precursor proteins, the prevalence, clinical manifestations, and pathogenesis of amyloidosis, and recent advances in our understanding of age-related amyloidoses outside the brain.

Increased extracellular water measured by bioimpedance analysis and increased serum levels of atrial natriuretic peptide in polymyalgia rheumatica patients : Signs of volume overload

BACKGROUND

Water retention is a typical feature of acute inflammatory episodes, chiefly implemented by the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis. This is an important compensatory mechanism counteracting expected water loss, e.g., due to sweating. Both the SNS and HPA axis are activated in polymyalgia rheumatica (PMR). As retention mechanisms may similarly apply in this disease, we hypothesized increased water retention in PMR.

METHODS

Using bioimpedance analysis body composition was investigated in 64 healthy controls and 32 treatment-naive PMR patients. All PMR patients satisfied the 2012 EULAR/ACR classification criteria for PMR. 32 PMR patients were tested before and after 7 days of glucocorticoid-based therapy. Serum levels of pro-atrial natriuretic peptide (proANP) were investigated in all PMR patients and 15 healthy controls.

RESULTS

Extracellular water (ECW) was markedly higher in PMR patients than in controls (mean ± SD: 49.1 ± 6.0% versus 36.3 ± 2.5% of total body water, p < 0.001). Patients with PMR demonstrated significantly higher serum levels of proANP compared to controls. Even before glucocorticoid treatment was initiated, systolic and diastolic blood pressure were higher in PMR patients compared to controls. Extracellular water levels did not change in PMR patients upon 7 days of intensified treatment.

CONCLUSION

This study demonstrated increased extracellular water and elevated serum levels of proANP as signs of fluid overload in patients with PMR. Volume changes are imprinted as long-lasting mechanisms as water distribution is not affected by short-term anti-inflammatory therapy.

Blood Pressure Variability and Atrial Fibrillation in Patients with Acute ST Segment Elevation Myocardial Infarction: The Relation with Left Atrial Electromechanical Delay - A 1-Year Follow-Up Study

Purpose

To investigate the association between 24-h blood pressure variability (BPV) and atrial electromechanical delay (EMD) in patients with ST segment elevation myocardial infarction (STEMI) who developed new-onset atrial fibrillation (NOAF).

Materials and Methods

A total of 175 STEMI patients (age 56.6 ± 10.5 years) who underwent primary percutaneous coronary intervention were subjected to in-hospital 24-h ambulatory BP monitoring, comprehensive echocardiography, and assessment of atrial EMD. The parameters of BPV analyzed were: (a) 24-h standard deviation (SD), (b) the coefficient of variation, and (c) the average of the daytime and nighttime SDs weighted for the duration of the daytime and nighttime interval (SD_dn ).

Results

Based on the median of BPV index (SD_dn) = 9.5 mm Hg of all participants, patients were stratified into low and high variability groups (SD_dn: 7.1 ± 1.5 vs.13.5 ± 2.9; p < 0.001). Of the 175 patients with STEMI, 29 (16.7%) patients developed NOAF; 26 (28.9%) were in the high variability group and 3.5% were in the low variability group (p < 0.001). Echocardiographic data showed that the left atrial volume index (p < 0.01) and E/e' ratio (p < 0.001) were significantly higher in patients with high BPV. Inter and intra-atrial EMD were significantly increased in the high variability group compared to the low variability group (p < 0.001). With multiple linear analysis, there was significant correlation between SD_dn and intra-left atrial and inter-atrial EMD (p < 0.001 and <0.01, respectively). Cox regression analysis revealed that SD_dn and intra-atrial EMD were independent predictors for NOAF in patients with STEMI (OR = 3.75 and 02.72, respectively; p < 0.001). ROC analysis revealed that SD_dn ≥12.8 was the optimal cut-off value for predicting NOAF during follow-up.

Conclusions

Short-term BPV was associated with NOAF during the 1-year follow-up in patients with STEMI. In addition, BPV was correlated significantly with atrial EMD. Herein, BPV was predicted to be an early predictor of NOAF in patients with STEMI.

Midregional proadrenomedullin predicts reduced blood pressure and glucose elevation over time despite enhanced progression of obesity markers

OBJECTIVES

Elevated plasma levels of the vasodilating hormone adrenomedullin (ADM) predict cardiovascular disease and have been associated with hypertension and obesity. We aimed to examine the independent relationship between ADM and the progression of major cardiometabolic risk factors during long-term follow-up.

METHODS

We studied midregional pro-ADM (MR-proADM) in fasting plasma in 3298 participants from the population-based Malmö Diet and Cancer Study - Cardiovascular Cohort, re-examined after 17 years of follow-up and related baseline MR-proADM to cardiometabolic risk factors cross-sectionally and longitudinally.

RESULTS

At baseline, after full adjustment, each SD increment of MR-proADM was independently related to (beta ± standard error, P value) higher SBP (0.956 ± 0.319 mmHg, P = 0.003), BMI (0.912 ± 0.061 kg/m, P = 1.42 × 10), waist (2.28 ± 0.158 cm, P = 8.46 × 10) and fasting blood glucose (0.046 ± 0.018 mmol/l, P = 0.01). After full adjustment, including the baseline level of the risk factor whose degree of progression was studied, each SD increment of MR-proADM predicted significantly reduced progression of SBP (-1.170 ± 0.337 mmHg, P = 0.001) and fasting blood glucose (-0.055 ± 0.023 mmol/l, P = 0.015), but greater increase of BMI (0.101 ± 0.051 kg/m, P = 0.047) and waist (0.600 ± 0.144 cm, P = 3.1 × 10).

CONCLUSION

Despite cross-sectional associations with higher levels of blood pressure and glucose, high levels of MR-proADM predict a slower progression of blood pressure and glycemia during long-term follow-up. Conversely, the cross-sectional associations with higher levels of MR-proADM and obesity were paralleled by a faster progression of obesity markers over time. These results may be important for assessment of long-term effects of therapies modulating levels of ADM.

Adrenomedullin has a role in angiogenic effects of resveratrol in adipose tissues of obese female rats

Obesity is a complex, chronic disease that arises according to the interaction between genetic and environmental factors. The expansion and growth of white adipose tissue (WAT) could be related to angiogenesis. Resveratrol and adrenomedullin (AdM) were used for the inhibition of angiogenesis in metabolically passive WAT for inhibiting the expansion of this tissue, and the activation of angiogenesis in metabolically active brown adipose tissue (BAT) for increasing daily energy consumption as a way of reducing obesity. Rats were divided into eight groups. Four obese groups were fed with a high-fat diet containing 60% fat as energy for three months. After obtaining obesity, 2.5 nmol/kg AdM and 10 mg/kg resveratrol were treated to experiment groups intraperitoneally (i.p.) every other day for four weeks. AdM and vascular endothelial growth factor A (VEGF-A) mRNA levels were detected with semi-quantitative PCR; protein levels were detected with Western Blotting. AdM and resveratrol are multifactorial molecules, thus, this study has revealed a few novel evidence. The results were distinct in the group and treatment levels. The results showed that resveratrol has a role in angiogenesis in obesity and contributed to AdM production. It is observed that AdM has regulated its expression and increased the effect of resveratrol in WAT. AdM and VEGF-A gene expressions could not be detected in BAT; however, it is suggested that resveratrol may have a pro-angiogenic effect in BAT of obese rats according to the protein levels. AdM also has regulated VEGF-A level according to the metabolic situation of the organism.

Five-week yin yoga-based interventions decreased plasma adrenomedullin and increased psychological health in stressed adults: A randomized controlled trial

Background

Non-communicable diseases (NCDs, e.g. cardiovascular disease) are responsible for high rates of morbidity and the majority of premature deaths worldwide. It is necessary to develop preventative interventions that can reduce the associated risk factors of NCDs. Researchers have found that the biomarker adrenomedullin (ADM) becomes elevated years before the onset of NCDs and might play an important role in their development. ADM has also been linked to psychological problems such as stress, anxiety, and depression, which are known risk factors of NCDs. In this randomized controlled trial, we examined whether participating in a five-week yoga intervention reduces ADM and increases psychological health in middle-aged adults who self-report as moderately to highly stressed, but who otherwise exhibit no physical complaints.

Methods

One hundred and five adults (78% women; mean age = 53.5, SD = 6.7) were randomly assigned to (1) a five-week Yin yoga intervention, (2) a five-week intervention combining Yin yoga with psychoeducation and mindfulness practice (called the YOMI program), or (3) a control group who did not practice yoga or mindfulness for five weeks.

Results

Compared to the control group, we observed significantly greater pre-post reductions in plasma ADM levels (p < .001), anxiety (p ≤ .002), and sleep problems (p ≤ .003) in both intervention groups. Furthermore, the YOMI group exclusively showed significantly greater pre-post reductions in stress (p = .012) and depression (p = .021) compared to the control group. Significant correlations (p < .05) were found between pre-post reductions in ADM and anxiety symptoms (p = .02) and depression (p = .04) in the entire sample.

Conclusion

The five-week Yin yoga-based interventions appeared to reduce both the physiological and psychological risk factors known to be associated with NCDs. The study suggests that incorporating Yin yoga could be an easy and low-cost method of limiting the negative health effects associated with high stress.

Trial registration

ClinicalTrials.gov NCT03428542

Adrenomedullin Contributes to Age-Related Memory Loss in Mice and Is Elevated in Aging Human Brains

Memory decline is common in elderly individuals and is the hallmark of Alzheimer’s disease (AD). Memory failure follows the loss of synaptic contacts in the cerebral cortex and hippocampus, caused in part by cytoskeleton disruption. Adrenomedullin (AM) and its gene-related peptide, proadrenomedullin N-terminal 20 peptide (PAMP), are microtubule-associated proteins (MAP) whose expression has been identified as a potential biomarker for predicting progression from predementia to clinical AD. Here we analyze the connection between AM levels and memory preservation. Mice lacking neuronal AM and PAMP (knockout, KO) and their wild type (WT) littermates were subjected, at different ages, to the novel object recognition test and the contextual fear conditioned test. Aged KO mice have significantly better retention memory than their WT counterparts. This feature was more prominent in females than in males. Prefrontal cortex and hippocampus samples from these animals were subjected to Western blotting for phospho-Tau and acetylated tubulin. Aged female KO mice had significantly less accumulation of phospho-Tau than their WT littermates. In addition, protein extracts from the frontal cortex of non-demented mature (65.10 ± 3.86 years) and aged (77.14 ± 2.77 years) human donors were analyzed by Western blotting. Aged human brains had significantly higher levels of AM and lower levels of acetylated tubulin than younger donors. These observations suggest that drugs or interventions that reduce AM/PAMP expression may constitute a new avenue to prevent memory decline during normal aging and in patients suffering moderate AD in high risk of rapid cognitive decline.

Targeting Adrenomedullin to Improve Lipid Homeostasis in Diabetic Pregnancies

Context

Gestational diabetes mellitus (GDM) is associated with disturbances in maternal lipid metabolism. Hypertriacylglycerolemia in GDM is associated with an increased risk of large for gestational age neonates, but the pathogenesis of disrupted lipid homeostasis remains unclear.

Objectives

To determine the role of adrenomedullin (AM), a multifunctional peptide, in lipid metabolism in GDM.

Design

Omental adipose biopsies were collected in term pregnancy from women with normal glucose tolerance (NGT, n = 10) and GDM (n = 10).

Results

AM and its receptor components, calcitonin receptor-like receptor, receptor activity-modifying protein 2, and receptor activity-modifying protein 3, were higher in adipose tissues from GDM compared with NGT pregnancies, and these expressions in normal adipose tissues were enhanced by glucose and tumor necrosis factor-αin vitro. AM dose- and time-dependently stimulated lipolysis in human adipocytes, and this effect was reversed by AM antagonist AM22-52. Furthermore, AM inhibited phosphorylation of insulin receptor-β and insulin receptor substrate-1 and enhanced the protein expression of leptin and resistin in adipose tissue from NGT women. The increased messenger RNA expression of leptin and resistin in adipose tissue from GDM was reduced by AM22-52 treatment.

Conclusions

GDM pregnancies are associated with increased AM and its receptor expression in adipose tissues. AM stimulates lipolysis and leptin and resistin expression, and these effects can be reversed by AM antagonist. To our knowledge, manipulation of AM and its receptors in adipocytes might represent an approach in reducing the risk of GDM and fetal overgrowth.

Relations of Arterial Stiffness and Brachial Flow-Mediated Dilation With New-Onset Atrial Fibrillation: The Framingham Heart Study

The relations of measures of arterial stiffness, pulsatile hemodynamic load, and endothelial dysfunction to atrial fibrillation (AF) remain poorly understood. To better understand the pathophysiology of AF, we examined associations between noninvasive measures of vascular function and new-onset AF. The study sample included participants aged ≥45 years from the Framingham Heart Study offspring and third-generation cohorts. Using Cox proportional hazards regression models, we examined relations between incident AF and tonometry measures of arterial stiffness (carotid-femoral pulse wave velocity), wave reflection (augmentation index), pressure pulsatility (central pulse pressure), endothelial function (flow-mediated dilation), resting brachial arterial diameter, and hyperemic flow. AF developed in 407/5797 participants in the tonometry sample and 270/3921 participants in the endothelial function sample during follow-up (median 7.1 years, maximum 10 years). Higher augmentation index (hazard ratio, 1.16; 95% confidence interval, 1.02-1.32; P=0.02), baseline brachial artery diameter (hazard ratio, 1.20; 95% confidence interval, 1.01-1.43; P=0.04), and lower flow-mediated dilation (hazard ratio, 0.79; 95% confidence interval, 0.63-0.99; P=0.04) were associated with increased risk of incident AF. Central pulse pressure, when adjusted for age, sex, and hypertension (hazard ratio, 1.14; 95% confidence interval, 1.02-1.28; P=0.02) was associated with incident AF. Higher pulsatile load assessed by central pulse pressure and greater apparent wave reflection measured by augmentation index were associated with increased risk of incident AF. Vascular endothelial dysfunction may precede development of AF. These measures may be additional risk factors or markers of subclinical cardiovascular disease associated with increased risk of incident AF.

Plasma levels of intermedin (adrenomedullin-2) in healthy human volunteers and patients with heart failure

Intermedin/adrenomedullin-2 (IMD) is a member of the adrenomedullin/CGRP peptide family. Less is known about the distribution of IMD than for other family members within the mammalian cardiovascular system, particularly in humans. The aim was to evaluate plasma IMD levels in healthy subjects and patients with chronic heart failure. IMD and its precursor fragments, preproIMD(25-56) and preproIMD(57-92), were measured by radioimmunoassay in 75 healthy subjects and levels of IMD were also compared to those of adrenomedullin (AM) and mid-region proadrenomedullin(45-92) (MRproAM(45-92)) in 19 patients with systolic heart failure (LVEF<45%). In healthy subjects, plasma levels (mean+SE) of IMD (6.3+0.6 pg ml(-1)) were lower than, but correlated with those of AM (25.8+1.8 pg ml(-1); r=0.49, p<0.001). Plasma preproIMD(25-56) (39.6+3.1 pg ml(-1)), preproIMD(57-92) (25.9+3.8 pg ml(-1)) and MRproAM(45-92) (200.2+6.7 pg ml(-1)) were greater than their respective bioactive peptides. IMD levels correlated positively with BMI but not age, and were elevated in heart failure (9.8+1.3 pg ml(-1), p<0.05), similarly to MRproAM(45-92) (329.5+41.9 pg ml(-1), p<0.001) and AM (56.8+10.9 pg ml(-1), p<0.01). IMD levels were greater in heart failure patients with concomitant renal impairment (11.3+1.8 pg ml(-1)) than those without (6.5+1.0 pg ml(-1); p<0.05). IMD and AM were greater in patients receiving submaximal compared with maximal heart failure drug therapy and were decreased after 6 months of cardiac resynchronization therapy. In conclusion, IMD is present in the plasma of healthy subjects less abundantly than AM, but is similarly correlated weakly with BMI. IMD levels are elevated in heart failure, especially with concomitant renal impairment, and tend to be reduced by high intensity drug or pacing therapy.

Mid-regional-pro-adrenomedullin plasma levels are increased in obese adolescents

PURPOSE

Recently, adrenomedullin (ADM) was defined as a new member of the adipokine family. ADM secreted by adipocytes, through its vasodilator and antioxidant actions, might be protective against metabolic syndrome-associated cardiovascular complications. The aim of the study was to assess plasma mid-regional (MR)-proADM levels in obese adolescents compared to normal-weight subjects and its relation with BMI, body composition and metabolic indices.

METHODS

Plasma MR-proADM was measured in 32 healthy adolescents [BMI z-score (mean ± SEM) = 0.6 ± 0.09 and 0.8 ± 0.07 in females and males, respectively] and in 51 age-matched obese adolescents [BMI z-score (mean ± SEM) = 2.8 ± 0.12 and 2.9 ± 0.08 in female and males, respectively] by a time-resolved amplified cryptate emission technology assay.

RESULTS

Plasma MR-proADM levels resulted significantly higher in obese than in normal-weight adolescents (MR-proADM: 0.33 ± 0.1 vs 0.40 ± 0.1 nmol/L, p < 0.0001). Using univariate analysis, we observed that MR-proADM correlated significantly with BMI z-score (p < 0.0001), fat mass (p < 0.0001), circulating insulin (p < 0.004), HOMA-IR (p < 0.005), total cholesterol (p < 0.03) and LDL-cholesterol (p < 0.05). Including MR-proADM as response variable and its significant correlates into a multiple regression analysis, we observed that fat mass (p = 0.014) and BMI z-score (p = 0.036) were independent determinants of circulating MR-proADM.

CONCLUSIONS

Our study shows for the first time that obese adolescents have higher circulating levels of MR-proADM compared with normal-weight, appropriate controls suggesting its important involvement in obese patients.

Effect of environmental salinity on expression of adrenomedullin genes suggests osmoregulatory activity in the medaka, Oryzias latipes

INTRODUCTION

The adrenomedullins (AMs) comprise a hormonal family in mammals and teleost fishes, with five members (AM1-5) found or predicted in most of the teleosts including Japanese medaka (Oryzias latipes). AM1 is known to have cardiovascular and osmoregulatory functions in mammals, but the roles of most AMs are yet to be determined.

RESULTS

Using medaka, we first analyzed the tissue distribution of all five AM genes and found detectable expression in all tissues examined, with relatively high levels of AM3 and AM5 in the liver and kidney. To assess the osmoregulatory roles of these AMs, mRNA levels were examined in the brain (including the eyes), gill, liver, kidney and spleen of medaka one week after transfer from isotonic saline (11 ppt) to freshwater (0 ppt) or seawater (33 ppt). Expression of AM1 in the brain-eye increased in freshwater. The central level of AM4 (the paralog of AM1) decreased in seawater; the branchial level of AM4 decreased in freshwater and seawater, but the renal level increased in freshwater. The branchial level of AM2 increased in seawater, whereas the renal level decreased in freshwater and seawater. Expression of AM3, the AM2 paralog, decreased in the brain-eye of seawater-acclimated fish. Expression of AM5 in the brain-eye and kidney decreased in seawater.

CONCLUSIONS

Except for branchial AM2, the members of AM family tend to be involved in promotion of hyper-osmoregulation and/or inhibition of hypo-osmoregulation, although each AM may play a distinct role during adaptation to different salinities.

Gender-related alterations in plasma adrenomedullin level and its correlation with body weight gain

Plasma levels of adrenomedullin (AM), a bioactive peptide produced in adipose tissue, have been shown to be higher in obese patients than in non-obese patients, but little is known about gender differences in plasma AM levels. The aims of this study were to clarify gender-related alterations in plasma AM levels and to examine the body weight (BW) gain-plasma AM relationship in the general population. We measured plasma AM levels of 346 local residents (62.0±8.9 years, mean±s.d.) in the Kiyotake area, Japan, who underwent a regular health check-up, by a specific fluorescence immunoassay. Plasma AM levels in the female residents were lower than that in the males, and multiple regression analysis revealed a possible gender difference in plasma AM. The AM levels were significantly correlated with BMI or waist circumference in women, but such a relationship was not seen in men. When the subjects were divided into two groups by results of a questionnaire about BW gain of 10 kg or more since the age of 20 years, the plasma AM level of women with BW gain ≧10 kg was significantly higher than that in those without BW gain, although no difference was noted between the men with and without BW gain. In conclusion, possible gender differences were noted in the plasma AM levels and in the BW gain-plasma AM relationship in the general population. The plasma AM levels in the female residents without BW gain seem partly attributable to the lower AM of women.

Adrenomedullin: possible predictor of insulin resistance in women with polycystic ovary syndrome

The aim of the study was to investigate adrenomedullin (ADM) levels and its relation with insulin resistance in women with polycystic ovary syndrome (PCOS). Twenty-nine women with PCOS and 29 age- and body mass index (BMI)- matched control subjects were included in the study. PCOS was defined according to criteria by the Rotterdam European Society of Human Reproduction and Embryology/American Society for Reproductive Medicine (ESHRE/ASRM)-sponsored PCOS consensus workshop group. A full clinical and biochemical examination including basal hormones and metabolic profile was performed. Insulin resistance was calculated by using the homeostasis model assessment of insulin resistance index (HOMA-IR). Plasma ADM levels were measured by high performance liquid chromatographic (HPLC) method. Plasma ADM, fasting insulin levels and HOMA-IR were significantly higher in patients with PCOS than the control group. ADM levels were positively correlated with insulin levels and HOMA-IR index. The best cut-off value of ADM levels to identify the presence of insulin resistance (HOMA-IR≥2.7) was 30.44 ng/ml. Calculated odds ratio of insulin resistance by using logistic regression analysis, as predicted by ADM, was 0.15 (95% confidence interval, 0.037-0.628; p=0.009). In multiple regression analysis, ADM level was an independent predictor of HOMA-IR index. Our finding indicated that ADM levels increased in women with PCOS in accordance with HOMA-IR. ADM could be a significant independent determinant of insulin resistance in women with PCOS.

Plasma adrenomedullin concentration in dogs with myxomatous mitral valvular disease

Adrenomedullin (AM), a peptide identified to have vasodilating and natriuretic effects, is involved in the regulation of the cardiovascular system. To evaluate plasma AM concentration in dogs with myxomatous mitral valvular disease (MMVD), and to investigate the associations between the concentrations of plasma AM and natriuretic peptides and the echocardiographic data, we evaluated plasma AM concentrations in 31 healthy control dogs and 57 dogs with MMVD. Plasma AM concentrations in dogs with MMVD were higher than that in the control subjects. The plasma AM concentration increased in conjunction with the severity of heart failure according to the International Small Animal Cardiac Health Council (ISACHC). The AM concentrations were 25.1 ± 5.0 fmol/ml (ISACHC class Ia), 29.9 ± 11.0 fmol/ml (ISACHC class Ib), 43.4 ± 19.8 fmol/ml (ISACHC class II) and 73.5 ± 21.7 fmol/ml (ISACHC class III) and 7.5 ± 5.1 fmol/ml (control group), respectively. The receiver operating characteristic curve indicated an area of 0.93 (95% CI, 0.8801-0.9889; <0.0001), a cutoff value of 30.5 fmol/ml, a sensitivity of 87.1%, and a specificity of 82.5% for the determination of congestive heart failure. Plasma AM concentrations correlated with atrial natriuretic peptide concentrations, LA/Ao ratio, and left ventricular diameter. In conclusion, AM may be a potential diagnostic marker for canine MMVD and possibly plays a pathophysiological role in collaboration with the other neurohumoral factors such as natriuretic peptides.

Arterial stiffness is associated with tissue Doppler atrial conduction times and P wave dispersion in hypertensive patients

BACKGROUND

Arterial stiffness is strongly predictive for cardiovascular events in hypertensive individuals and it may increase the risk of stroke. This study was designed to evaluate the possible relationship between arterial stiffness and atrial electromechanical delay and P wave dispersion (PWD), as determinants of AF risk.

MATERIALS AND METHODS

The study included 75 hypertensive patients and 45 healthy control subjects. Atrial electromechanical coupling (time interval from the onset of P wave on ECG to the beginning of A wave with tissue Doppler echocardiography [PA]), intraatrial and interatrial electromechanical delay (EMD) and PWD were measured. Stiffness index β & PWV was measured to assess the arterial stiffness.

RESULTS

The interatrial EMD and PWD were prolonged in hypertensive patients compared to controls (p<0.01 for both), There was increased arterial stiffness (PWV and stiffness index β) in hypertensive patients compared to controls (6.43 ± 1.73 vs. 4.8 ± 1.6 m/sec & 4.9 ± 2.8 vs. 2.63 ± 1.2, p<0.01 for both). By multivariate analysis; PWV and Stiffness index β were independently correlated with interatrial EMD (B ± SE=0.42 ± 1.87, B ± SE=0.39 ± 0.21 p<0.01 for both) and PWD (B ± SE=0.37 ± 1.93, p<0.01, B ± SE=0.25 ± 0.18, p<0.05 respectively).

CONCLUSION

In hypertensive patients arterial stiffness indexes increased and showed a significant correlation with interatrial EMD and PWD independent of other variables. Further research is needed to determine whether interventions that reduce arterial stiffness will limit the growing incidence of AF.

Plasma adrenomedullin level is related to a single nucleotide polymorphism in the adrenomedullin gene

OBJECTIVE

Adrenomedullin (ADM) plays an important role in inflammation and is a marker of future cardiovascular events. We studied common single nucleotide polymorphisms (SNPs) in the gene encoding ADM and their relationship with the plasma levels of ADM and other inflammatory markers.

DESIGN AND METHODS

Plasma ADM, interleukin 6 (IL6), fibrinogen, and C-reactive protein (CRP) were measured in 476 subjects from the population-based Hong Kong Cardiovascular Risk Factor Prevalence Study-2. Four tag SNPs in ADM were genotyped.

RESULTS

Plasma ADM level increased with decreasing plasma IL6 level (β=-0.116, P=0.014). Plasma ADM level was not related to plasma levels of CRP and fibrinogen, and other clinical characteristics, except age (P=0.049). The four SNPs, rs3814700, rs11042725, rs34354539, and rs4910118, had minor allele frequencies of 31.1, 28.7, 33.8, and 23.4% respectively. Carriers of the minor allele of rs4910118 had a mean plasma ADM level that was 10.5% (95% confidential interval: 2.5-17.8%) lower than the non-carriers (β=-0.115, P=0.011). Haplotype analysis revealed a similar significant association with plasma ADM (P=0.040). In multivariate analysis, the presence of the minor allele of rs4910118, but not plasma IL6, was independently associated with plasma ADM (P=0.010).

CONCLUSION

Plasma ADM correlates with plasma IL6 level, consistent with its role in inflammation. It is related to an SNP common in Chinese, independent of other covariates. ADM genotype should be included in future studies of cardiovascular risk prediction.

Cardiovascular and hormonal responses to static handgrip in young and older healthy men

The purpose of this study was to investigate the effect of age on cardiovascular changes and plasma concentrations of adrenomedullin (ADM), catecholamines, endothelin-1 (ET-1) and plasma renin activity (PRA) in healthy men. A total of 15 young (21 ± 0.3 years) and 15 older (64 ± 0.7 years) healthy men performed two 3-min bouts of static handgrip at 30% of maximal voluntary contraction, alternately with each hand without any break between the bouts. During exercise heart rate (HR), blood pressure (BP), stroke volume (SV) and pre-ejection period (PEP) and left ventricle ejection time (LVET) were measured. Blood samples were taken before exercise, at the end of both exercise bouts and in the fifth minute of the recovery period. The handgrip-induced increases in HR and cardiac output were significantly smaller in older than in young men (p < 0.01). SV decreased only in older men (p < 0.001). There were no differences between groups in BP increases. The baseline plasma ADM and catecholamines were higher in older man compared to young subjects. Handgrip caused increases in plasma ADM, ET-1 and PRA only in older men (p < 0.05). The increases in plasma ADM correlated positively with those of noradrenaline (NA), PRA, ET-1 and LVET and negatively with changes in total peripheral resistance (TPR), SV, PEP and PEP/LVET ratio. The increases in plasma ET-1 correlated positively with those of NA, PRA, TPR, mean BP and SV. These results revealed that ADM, ET-1 and angiotensin II can contribute to maintain vascular tone during static exercise in older but not in younger men.

Systolic pressure, diastolic pressure, or pulse pressure as a cardiovascular risk factor in renal disease

Chronic kidney disease is a leading global health problem with an increasing prevalence. Hypertension is present in most patients with chronic kidney disease, and hypertension-related nephrosclerosis is a top cause of progressive renal damage and end-stage renal disease. Systolic blood pressure (BP) and pulse pressure, together with nocturnal BP, are the most important factors favoring the progression of renal failure. Consequently, strict control of BP and other cardiovascular risk factors is required, including an adequate degree of suppression of the renin-angiotensin system in every patient.

A spontaneous, double-blind, double-dummy cross-over study on the effects of daily vardenafil on arterial stiffness in patients with vasculogenic erectile dysfunction

BACKGROUND

It is known that the incidence of endothelial dysfunction in patients with vascular erectile dysfunction (ED) is increased. The effects of daily vardenafil on endothelial function and arterial stiffness in patients with erectile dysfunction (ED) have never been investigated.

METHODS

20 men complaining vascular ED (mean IIEF5=12 ± 6 and peak systolic velocity-PSV=24 ± 2 cm/s) were enrolled in a 4-week, randomized, double-blind, double-dummy, crossover study (mean age 59 ± 11) and received either vardenafil 10mg daily or 20mg on-demand with a two-week washout interval. Primary endpoints were variation from baseline of reactive hyperemia (RH) and augmentation index (AI) calculated by fingertip peripheral arterial tonometry (PAT) device. Secondary endpoints were variations of IIEF-5 and SEP3 scores from baseline and plasma surrogate markers of endothelial function, i.e. endothelin-1 (ET-1) and adrenomedullin (ADM).

RESULTS

Patients who took daily vardenafil (vs. on-demand) reported significant (P<0.01) improvements in arterial stiffness as evaluated by AI and reduction of plasma ADM levels (p<0.05) but no improvement in average RH. When corrected for heart rate, ADM showed a strong direct relationship with AI (r(2)=0.22; p<0.005). The proportion of patients with an IIEF5 score of ≥ 22 or in SEP3 percentage of success rates were similar. Each treatment resulted in significantly greater IIEF5 scores (p<0.001) and better SEP3 response rates (p<0.0001) compared with baseline.

CONCLUSIONS

We demonstrated that daily vardenafil improves arterial stiffness and erectile function measurements in men with severe vasculogenic ED. This effect may be mediated, at least in part, by a reduction in ADM circulating levels.

A genetic variant in the gene encoding adrenomedullin predicts the development of dysglycemia over 6.4 years in Chinese

BACKGROUND

Adrenomedullin, a vasodilatory peptide, facilitates the differentiation of pre-adipocytes, and affects lipolysis and glucose uptake. We investigated the association of common single nucleotide polymorphisms (SNPs) in the gene encoding adrenomedullin (ADM) with dysglycemia in the Hong Kong Chinese population.

METHODS

Four SNPs were genotyped in 1391 subjects without dysglycemia at baseline from the Hong Kong Cardiovascular Risk Factor Prevalence Study-2, which had a median follow-up time of 6.4 years. Dysglycemia included impaired fasting glucose, impaired glucose tolerance, and diabetes according to the WHO 1998 criteria. At follow-up, 382 subjects had developed dysglycemia.

RESULTS

In stepwise logistic regression, the SNP rs11042725 was a significant independent predictor of the development of dysglycemia (OR=1.31, P=0.012), together with baseline age (P<0.001), plasma triglycerides (P<0.001), body mass index (P=0.004), 2-h glucose after oral glucose tolerance test (P<0.001), homeostasis model assessment of insulin resistance index (P=0.045), and follow-up duration (P=0.009). The association was more significant in women (P=0.002) and in subjects without regular exercise (P=0.001).

CONCLUSIONS

Our study suggests a potential role of genetic variants in the ADM gene in the development of dysglycemia in our local Chinese population.

Multiple marker approach to risk stratification in patients with stable coronary artery disease

AIMS

multimarker approaches for risk prediction in coronary artery disease have remained inconsistent. We assessed multiple biomarkers representing distinct pathophysiological pathways in relation to cardiovascular events in stable angina.

METHODS AND RESULTS

we investigated 12 biomarkers reflecting inflammation [C-reactive protein, growth-differentiation factor (GDF)-15, neopterin], lipid metabolism (apolipoproteins AI, B100), renal function (cystatin C, serum creatinine), and cardiovascular function and remodelling [copeptin, C-terminal-pro-endothelin-1, mid-regional-pro-adrenomedullin (MR-proADM), mid-regional-pro-atrial natriuretic peptide (MR-proANP), N-terminal-pro-B-type natriuretic peptide (Nt-proBNP)] in 1781 stable angina patients in relation to non-fatal myocardial infarction and cardiovascular death (n = 137) over 3.6 years. Using Cox proportional hazards models and C-indices, the strongest association with outcome for log-transformed biomarkers in multivariable-adjusted analyses was observed for Nt-proBNP [hazard ratio (HR) for one standard deviation increase 1.65, 95% confidence interval (CI) 1.28-2.13, C-index 0.686], GDF-15 (HR 1.59, 95% CI 1.25-2.02, C-index 0.681), MR-proANP (HR 1.46, 95% CI 1.14-1.87, C-index 0.673), cystatin C (HR 1.39, 95% CI 1.10-1.75, C-index 0.671), and MR-proADM (HR 1.63, 95% CI 1.21-2.20, C-index 0.668). Each of these top single markers and their combination (C-index 0.690) added predictive information beyond the baseline model consisting of the classical risk factors assessed by C-index and led to substantial reclassification (P-integrated discrimination improvement <0.05).

CONCLUSION

comparative analysis of 12 biomarkers revealed Nt-proBNP, GDF-15, MR-proANP, cystatin C, and MR-proADM as the strongest predictors of cardiovascular outcome in stable angina. All five biomarkers taken separately offered incremental predictive ability over established risk factors. Combination of the single markers slightly improved model fit but did not enhance risk prediction from a clinical perspective.

Increased plasma levels of the mature and intermediate forms of adrenomedullin in obesity

Adrenomedullin (AM) is a cardiovascular protective peptide produced in various organs and tissues including adipose tissue. In the present study, we measured the plasma AM levels of subjects with or without obesity by two assay methods to separately evaluate the biologically active AM-NH(2) and the intermediate form of AM-glycine (AM-Gly). We measured the total AM and AM-NH(2) levels of plasma in 52 obese and 172 non-obese residents of a Japanese community, who received regular health check-ups and had no overt cardiovascular disease. AM-Gly values were obtained by subtracting AM-NH(2) levels from those of total AM. Both the AM-NH(2) and AM-Gly levels of the subjects with obesity were higher than those without obesity, and significant relationships were noted between body mass index (BMI) and the plasma levels of the two molecular forms of AM in a simple regression analysis. Moreover, the significant factors identified by multivariate analyses were BMI and serum triglyceride for AM-NH(2) and diastolic blood pressure, insulin, high-density lipoprotein-cholesterol, and plasma renin activity for AM-Gly. These results suggest active roles for the two molecular forms of AM in metabolic disorders associated with obesity in subjects without overt cardiovascular disease.

Relationship of urinary cGMP excretion with aging and menopausal status in a general population

AIM

Aging and postmenopausal women are associated with increased risks of cardiovascular disease; however, epidemiological evidence concerning the relationship of aging and the menopause with vascular biological activity is limited.

METHODS

We investigated the relationship of aging and the menopause with urinary excretion of cyclic guanosine 3',5' monophosphate (cGMP) in 1,541 Japanese men and women aged 40 to 79 years. The 24-hour urinary excretion of cGMP was measured with a (125)I-labeled cGMP radioimmunoassay and was adjusted for urinary creatinine excretion (nmol/mmol creatinine).

RESULTS

Aging was positively associated with urinary excretion of cGMP for both sexes. Postmenopausal women excreted significantly less urinary cGMP than premenopausal women after adjustment for age and other cardiovascular risk factors: 48.3+/-0.04 nmol/mmol vs. 61.5+/-0.07 nmol/mmol, p=0.006.

CONCLUSIONS

Our data suggest that cGMP-related vasodilatation is impaired in postmenopausal women.

Mid-regional pro-adrenomedullin is associated with pulse pressure, left ventricular mass, and albuminuria in African Americans with hypertension

BACKGROUND

African Americans with hypertension are prone to target-organ damage and adverse cardiovascular events. Biomarkers for early detection of target-organ damage in this ethnic group are needed. Adrenomedullin (ADM) is a circulating vasoactive peptide with vasodilatory and antiproliferative effects that has been reported to be elevated in adults with hypertension.

METHODS

We investigated the associations of plasma levels of mid-regional pro-ADM (MR-proADM) with pulse pressure, left ventricular mass (LVM), and albuminuria in 1,034 African-American adults (65 +/- 9 years, 72% women) with hypertension. MR-proADM was measured by an immunoluminometric assay, LVM was assessed by 2-dimensional echocardiography, and albuminuria was assessed by urine albumin:creatinine ratio (UACR). Multivariable regression analyses were used to assess whether plasma MR-proADM was independently associated with pulse pressure, LVM indexed by height to the power 2.7 (LVMi), and UACR.

RESULTS

Plasma MR-proADM was significantly correlated (P < 0.001) with pulse pressure, LVMi, and UACR. In separate multivariable linear regression models that adjusted for age and sex, log MR-proADM was associated with greater pulse pressure (P = 0.007), log LVMi (P = 0.001), and log (UACR+1) (P < 0.0001). After additional adjustment for body mass index (BMI), total and high-density lipoprotein (HDL) cholesterol, smoking history, diabetes, estimated glomerular filtration rate (eGFR), history of myocardial infarction (MI) or stroke, and medication use, log MR-proADM remained significantly associated with greater pulse pressure (P = 0.001), log LVMi (P = 0.029), and log (UACR+1) (P = 0.002).

CONCLUSIONS

In African-American adults with hypertension, plasma MR-proADM is independently associated with pulse pressure, LVMi, and albuminuria and is a potential biomarker for target organ damage.

Plasma MR-proADM correlates to BMI and decreases in relation to leptin after gastric bypass surgery

Adrenomedullin (ADM) is a vasoactive peptide found to be related to obesity and its comorbidities: type 2 diabetes, hypertension, atherosclerosis, and coronary heart disease. ADM is increased both in plasma and in adipose tissue of obese individuals when compared to lean subjects and is considered as a member of the adipokine family. We determined plasma midregional proadrenomedullin (MR-proADM) concentrations in a cohort of 357 subjects with BMI ranging from 17.5 to 42.3 kg/m2 and no additional medical history. In parallel, 28 severely obese patients scheduled to undergo laparoscopic Roux-en-Y gastric bypass (RYGB) surgery were studied at two time points: before and 1 year after surgery. Outcome measurements were: MR-proADM, cortisol, leptin, C-reactive protein (CRP) thyroid-stimulating hormone (TSH), creatinine and metabolic parameters. BMI correlated significantly to plasma MR-proADM levels (r=0.714, P<0.001), also after adjustment for age and gender (r=0.767, P<0.001). In obese subjects, there was a positive relationship between MR-proADM and leptin (r=0.511, P=0.006). Following RYGB, plasma MR-proADM decreased from 0.76+/-0.03 to 0.62+/-0.02 pg/ml (P<0.0001). RYGB-induced changes in MR-proADM correlated significantly to changes in leptin (r=0.533, P=0.004) and in CRP (r=0.429, P=0.023). We conclude that BMI is an independent predictor of circulating MR-proADM levels. Weight loss after RYGB is associated with a significant decrease in plasma MR-proADM, which is related to surgery-induced changes in both circulating leptin and systemic inflammation.

Association between perceived stress and plasma B-type natriuretic peptide concentrations

BACKGROUND

Many patients with heart disease continue to have cardiac events despite receiving optimal treatments for traditional risk factors. Consequently, non-traditional risk factors for heart disease, such as perceived stress, have attracted attention. Associations between perceived stress and plasma B-type natriuretic peptide (BNP) were explored, while controlling for traditional heart disease risk factors.

METHODS AND RESULTS

This cross-sectional study examined 360 male and 446 female (age, >40 years) residents of a rural Japanese community who received annual health checkups in 2006. A lifestyle questionnaire was used to obtain information regarding perceived stress and medical history, and routine anthropometric and blood pressure measurements and a laboratory assessment of cardiovascular risk factors, including plasma BNP concentrations and an electrocardiogram, were done. After adjusting for traditional heart disease risk factors, multiple regression analysis showed that perceived stress was associated with BNP concentrations, particularly in women (F=6.12, P=0.026). In addition, multiple tests using Bonferroni's procedure showed that BNP concentrations decreased with perceived stress level in men and women. Similar trends were observed in the sub-analyses of subjects with and without known heart disease.

CONCLUSIONS

Perceived stress in our study was negatively associated with plasma BNP concentrations, independently of traditional heart disease risk factors.

Restorative effect of atrial natriuretic peptide or chronic neutral endopeptidase inhibition on blunted cardiopulmonary vagal reflexes in aged rats

Arterial baroreflex function diminishes with age, but whether cardiopulmonary vagal reflexes are similarly altered with physiological aging has not been fully elucidated. In this study, predominantly cardiac high pressure mechanoreceptor-activated (ramp baroreflex) and cardiopulmonary chemoreceptor-activated (von Bezold-Jarisch reflex) vagal reflexes in conscious, instrumented rats were impaired by 30% to 40% (P<0.05) in 24-month-old (n=12) compared with 6-month-old rats (n=12). To determine whether this is a restorable deficit, the influence of atrial natriuretic peptide (ANP), either by infusion or blockade of its breakdown, was studied. ANP infusion was previously shown to enhance Bezold-Jarisch reflex and ramp baroreflex bradycardia in young adult rats. The present study confirmed that vagal reflex augmentation by ANP (50 pmol/kg per minute) also occurs in old rats (increased by 60+/-18% (Bezold-Jarisch reflex) and 91+/-15% (ramp baroreflex; P<0.05). Direct vagal stimulation in anesthetized animals showed that the target for ANP was not the cardiac vagus itself in old rats (n=7), although in young rats only, we confirmed the published finding that ANP enhances vagal bradycardia (by 58+/-14%, n=7). Neutral endopeptidase 24.11 degrades ANP and several other peptides. The neutral endopeptidase inhibitor candoxatrilat (5 mg/kg per day IV for 7 to 9 days) restored vagal reflex bradycardia in old rats (n=6) to levels similar to those in young neutral endopeptidase inhibitor-treated rats (n=6). Impaired cardiopulmonary vagal reflex control of heart rate is thus a feature of normal aging, and this deficit may be ameliorated by either ANP infusion or chronic neutral endopeptidase inhibition.

Dysregulation of pulsatility in aging IV. Pulsatile signaling and cardiovascular aging: functions and regulation of natriuretic peptide signaling

Atrial and brain natriuretic peptides (ANP and BNP) are cardiac hormones connecting heart and kidney and playing a key role in hydromineral and hemodynamic homeostasis. In contrast with the renin-angiotensin-aldosterone system, circulating ANP and BNP are not temporally related with rapid eye movement (REM)-nonREM sleep cycles, autonomic activity, or blood pressure. Cardiac natriuretic peptides are secreted in a pulsatile manner, with short periods of 20-48min, in normal as well as in pathological conditions. The frequency of pulses seems to be unchanged with aging, whereas the absolute amplitude of the oscillations seems to increase, most likely as a result of an increase in the plasma hormone levels observed in elderly. Enhanced cardiac secretion and decreased degradation partly explain the higher ANP and BNP concentrations observed in elderly. Despite higher levels, the natriuretic system seems to loose efficiency at the renal site in elderly. This more probably relies on reduced target organ responsivity and not on deeply altered hormone secretion. Here we review the impact of aging on the renal effects of the natriuretic peptides, and point out the lack of knowledge on the precise interactions between the ultradian rhythms of the systems involved in salt and water balance in elderly. Additional studies focusing on potential age-induced alterations of the intracellular signaling pathway are now needed.

Evaluation of adrenomedullin and endothelin-1: are they factors in the adaptation of maternal vascular system in normotensive pregnancy

INTRODUCTION

The aim of our study was to analyse the role of adrenomedullin (AM) and endothelin-1 (ET-1) in the adaptation of the maternal vascular system in normotensive pregnancy.

METHODS

Twenty-eight pregnant women, who were normotensive throughout the duration of their pregnancy, were recruited into the study. Plasma levels of AM and ET-1 at each trimester were measured and the AM/ET-1 ratio was calculated.

RESULTS

Our experiment showed a significant decrease in plasma concentrations of AM in the first trimester for the study group (n=28) compared with the non-pregnant control group (n=16). There was also a significant decrease in plasma concentrations of ET-1 in all three trimesters (P<0.05) and a significant increase in the AM/ET-1 ratio in all three trimesters (P<0.05) for the study group compared with the control group.

CONCLUSION

An alteration in vascular equilibrium between AM and ET-1, favouring AM, may be a reason why the physiological adaptation of the maternal vascular system to pregnancy occurs during normotensive pregnancy.

Intermedin (adrenomedullin-2): a novel counter-regulatory peptide in the cardiovascular and renal systems

Intermedin (IMD) is a novel peptide related to calcitonin gene-related peptide (CGRP) and adrenomedullin (AM). Proteolytic processing of a larger precursor yields a series of biologically active C-terminal fragments, IMD(1-53), IMD(1-47) and IMD(8-47). IMD shares a family of receptors with AM and CGRP composed of a calcitonin-receptor like receptor (CALCRL) associated with one of three receptor activity modifying proteins (RAMP). Compared to CGRP, IMD is less potent at CGRP(1) receptors but more potent at AM(1) receptors and AM(2) receptors; compared to AM, IMD is more potent at CGRP(1) receptors but less potent at AM(1) and AM(2) receptors. The cellular and tissue distribution of IMD overlaps in some aspects with that of CGRP and AM but is distinct from both. IMD is present in neonatal but absent or expressed sparsely, in adult heart and vasculature and present at low levels in plasma. The prominent localization of IMD in hypothalamus and pituitary and in kidney is consistent with a physiological role in the central and peripheral regulation of the circulation and water-electrolyte homeostasis. IMD is a potent systemic and pulmonary vasodilator, influences regional blood flow and augments cardiac contractility. IMD protects myocardium from the deleterious effects of oxidative stress associated with ischaemia-reperfusion injury and exerts an anti-growth effect directly on cardiomyocytes to oppose the influence of hypertrophic stimuli. The robust increase in expression of the peptide in hypertrophied and ischaemic myocardium indicates an important protective role for IMD as an endogenous counter-regulatory peptide in the heart.

Age-specific impact of self-monitored pulse pressure on hypertensive target organ damage in treated hypertensive patients

The authors examined the relationship of clinic and self-measured pulse pressure with target organ damage in 597 treated hypertensive patients without clinical evidence of renal dysfunction or a history of heart failure. The cross-sectional relationships of plasma brain natriuretic peptide (BNP) and urinary albumin/creatinine ratio with clinic and self-monitored pulse pressures were estimated in age tertile groups: younger than 67 years (n=193), 67 to 75 years (n=216), and older than 75 years (n=188), controlling for various confounding factors. In multivariable analyses, both clinic and self-monitored higher pulse pressures were associated with increased urinary albumin/creatinine ratio in all 3 age groups. Self-monitored higher pulse pressure, but not clinic pulse pressure, was consistently associated with increased BNP in the younger and middle-aged patients. In the very old (older than 75 years), however, there were no consistent associations between pulse pressure measures and BNP. More studies are needed in the evaluation of cardiac risk with hemodynamic measures in the very old.

Adrenomedullin is a novel adipokine: adrenomedullin in adipocytes and adipose tissues

Adrenomedullin (AM) is a multifunctional regulatory peptide that is produced and secreted by various types of cells. The production and the secretion of AM have been demonstrated in cultured adipocytes and adipose tissues. Inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and lipopolysaccharide are strong stimulators for AM expression in adipocytes. Furthermore, AM expression in the adipose tissue is increased in obesity, and plasma concentrations of AM are increased in obese subjects. One possible (patho)physiological role of AM secreted by adipose tissue may be actions against complications of the metabolic syndrome characterized by obesity, type 2 diabetic mellitus and hypertension, via its antioxidant and potent vasodilator effects. These findings indicate that AM is a new member of the adipokine family.

Type 2 diabetes and cardiovascular disease: getting to the fat of the matterThis paper is one of a selection of papers published in this Special Issue, entitled Young Investigators' Forum

The increasing national prevalence of obesity is a major public health concern and a substantial burden on the health care resources of Canada. In addition to the direct health impact of obesity, this condition is a well-established risk factor for the development of various prevalent comorbidities including type 2 diabetes, hypertension, and cardiovascular disease. Historically, adipose tissue has been regarded primarily as an organ for energy storage. However, the discovery of leptin in the mid 1990’s revolutionized our understanding of this tissue and has focused attention on the endocrine function of adipose tissue as a source of secreted bioactive peptides. These compounds, collectively termed adipokines, regulate a number of biological functions including appetite and energy balance, insulin sensitivity, lipid metabolism, blood pressure, and inflammation. The physiological importance of adipokines has led to the hypothesis that changes in the synthesis and secretion of these compounds in the obese are a causative factor contributing to the development of obesity and obesity-related diseases in these individuals. Following from this it has been proposed that pharmacologic manipulation of adipokine levels may provide novel effective therapeutic strategies to treat and prevent obesity, type 2 diabetes, and cardiovascular disease.

Adrenomedullin in adipocyte differentiation of human mesenchymal stem cells

Expression of adrenomedullin (AM), a potent vasodilator peptide, was studied during adipocyte differentiation of human mesenchymal stem cells (hMSCs). Immunoreactive AM levels in the medium were increased at day 4 and 8 of the adipocyte differentiation. Northern blot analysis showed increased expression of AM mRNA in hMSCs-derived adipocytes at day 4, 8, 12, and 18. Transient transfection assay showed that the promoter activity was higher in hMSCs-derived adipocytes than in hMSCs, when cells were transfected with plasmids containing a cis-acting region (-70/-29) of the human AM gene. Electrophoretic mobility shift assay showed that specific bands bound to the region (-70/-29) in hMSCs-derived adipocytes but not in hMSCs, and were abolished by the stimulatory protein 1 (Sp1) antibody. The present study has shown that AM expression is up-regulated during adipocyte differentiation of hMSCs probably via the interaction between Sp1 or Sp1-related factor(s) and the AM promoter region (-70/-29).