Low levels of asymmetric dimethylarginine in children with diabetes mellitus type I compared with healthy children

The Predictive Role of Plasma Biomarkers in the Evolution of Aortopathies Associated with Congenital Heart Malformations

Dilatation of the aorta is a constantly evolving condition that can lead to the ultimate life-threatening event, acute aortic dissection. Recent research has tried to identify quantifiable biomarkers, with both diagnostic and prognostic roles in different aortopathies. Most studies have focused on the bicuspid aortic valve, the most frequent congenital heart disease (CHD), and majorly evolved around matrix metalloproteinases (MMPs). Other candidate biomarkers, such as asymmetric dimethylarginine, soluble receptor for advanced glycation end-products or transforming growth factor beta have also gained a lot of attention recently. Most of the aortic anomalies and dilatation-related studies have reported expression variation of tissular biomarkers. The ultimate goal remains, though, the identification of biomarkers among the serum plasma, with the upregulation of circulating MMP-1, MMP-2, MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), asymmetric dimethylarginine (ADMA), soluble receptor for advanced glycation end-products (sRAGE) and transforming growth factor beta (TGF-β) being reported in association to several aortopathies and related complications in recent research. These molecules are apparently quantifiable from the early ages and have been linked to several CHDs and hereditary aortopathies. Pediatric data on the matter is still limited, and further studies are warranted to elucidate the role of plasmatic biomarkers in the long term follow-up of potentially evolving congenital aortopathies.

Asymmetric dimethylarginine is not a marker of arterial damage in children with glomerular kidney diseases

Introduction

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, correlates with cardiovascular risk especially in patients with chronic kidney disease. The aim of our study was to establish significance of ADMA as a biomarker of arterial damage in children with glomerulopathies.

Material and methods

In 80 children with glomerulopathies (mean age, 11.33 ±4.25 years; 42 with idiopathic nephrotic syndrome [INS], 38 with IgA or Henoch-Schoenlein nephropathy [IgAN/HSN]), we analyzed serum ADMA [nmol/ml], peripheral and central blood pressure, arterial stiffness (augmentation index – AIx75HR, pulse wave velocity – PWV), common carotid artery intima media thickness (cIMT), and selected clinical and biochemical parameters.

Results

In the study group, mean ADMA concentration was 1.66 ±1.19 [nmol/ml] and did not differ between INS and IgAN/HSN patients. We found no significant correlations between concentration of ADMA, cIMT [mm]/Z-score, PWV [m/s]/Z-score, and AIx75HR [%] in the whole group and in INS and IgAN/HSN patients. In the whole group of 80 children, ADMA correlated (p < 0.05) with BMI Z-score (r = –0.24), uric acid (r = –0.23), HDL-cholesterol (r = –0.25), and central mean arterial pressure (r = –0.25), in children with INS also with total protein (r = 0.37), albumin (r = 0.36), and total cholesterol (r = –0.40, p = 0.028). In multivariate analysis, serum albumin was the strongest determinant of ADMA in the whole group (β = 0.536, 95% CI: 0.013-1.060, p = 0.045).

Conclusions

1. In children with glomerulonephritis, measurement of asymmetric dimethylarginine cannot replace well established and validated methods of assessment of subclinical arterial damage. 2. In children with glomerular kidney diseases, ADMA concentration is related primarily to serum albumin concentration.

Asymmetric dimethylarginine levels and diabetes duration: Relationship with measures of subclinical atherosclerosis and cardiac function in children and adolescents with Type 1 diabetes

AIMS

We aimed to evaluate asymmetric dimethylarginine levels in young patients with Type 1 diabetes mellitus according to diabetes duration and to examine the relationship between these levels and measures of atherosclerosis and myocardial function.

MATERIALS AND METHODS

In total, 83 patients (8.5-22 years) with Type 1 diabetes mellitus were stratified by diabetes duration: 12-60 months (Group 1, n = 27), >60-120 months (Group 2, n = 29) and >120 months (Group 3, n = 27). Asymmetric dimethylarginine levels were assessed. Carotid intima-media thickness was measured. Myocardial function was assessed by M-mode, conventional Doppler and tissue Doppler echocardiography.

RESULTS

Asymmetric dimethylarginine level was significantly higher in Group 1, while carotid intima-media thickness was significantly greater in Group 3 ( p < 0.05). Tissue Doppler echocardiography showed the ratio of peak early to peak late diastolic myocardial annular velocity decreased significantly in Groups 2 and 3 with a negative correlation with duration (r: -0.310, p = 0.004) and HBA1c levels (r = -0.391, p < 0.001). Myocardial performance index in all groups and isovolumic relaxation time in Group 3 increased significantly. Asymmetric dimethylarginine levels were negatively correlated with carotid intima-media thickness and isovolumic relaxation time ( p < 0.05).

CONCLUSION

In contrast to adult diabetics, asymmetric dimethylarginine concentration decreases as diabetes duration increases in young Type 1 diabetic patients and is associated with worsening measures of cardiovascular risk and poorer diastolic function.

Osteoprotegerin, RANKL, ADMA, and Fetuin-A serum levels in children with type I diabetes mellitus

INTRODUCTION

Patients with type I diabetes mellitus (T1DM) have increased incidence of atherosclerosis and cardiovascular disease. Although these complications are unusual in children with T1DM, prevention, and early intervention could decrease morbidity and mortality. Osteoprotegerin (OPG), asymmetric dimethylarginine (ADMA), and Fetuin-A have been associated with increased cardiovascular risk (CVR). Increased OPG and ADMA, and decreased or increased Fetuin-A serum levels have been associated with increased CVR.

AIM

Because patients with T1DM have higher CVR we investigated OPG, ADMA, and Fetuin-A, in children with T1DM.

METHODS

We determined the serum levels of OPG, receptor activator of nuclear factor-κB ligand (RANKL), ADMA, and Fetuin-A by enzyme-linked immunosorbent assay (ELISA) in 56 children with T1DM aged 12.1 ± 3.4 yr and in 46 normal control children, (C) aged 11.3 ± 3.0 yr.

RESULTS

Serum OPG levels were significantly increased in patients with T1DM (3.352 ± 0.73 pmol/L) compared with C (2.75 ± 0.67 pmol/L, p < 0.0001) but RANKL did not change. ADMA was significantly decreased in T1DM compared with C (0.68 ± 0.13 µmol/L versus 0.82 ± 0.18 µmol/L, p < 0.0001). Fetuin-A was similar in T1DM (0.551 ± 0.13 g/L) and C (0.540 ± 0.11 g/L) subjects. OPG was positively associated with glycosylated hemoglobin A1c (p < 0.001) and negatively associated with BMI (p < 0.01). ADMA and Fetuin-A were not associated with A1c and ADMA was only negatively associated with age (p < 0.05).

CONCLUSION

OPG is increased, ADMA is decreased, but RANKL and Fetuin-A are unchanged in T1DM children. Whereas increased OPG has been firmly related to increased CVR, more studies, especially longitudinal studies, are needed to delineate the role and clinical significance of decreased ADMA and if Fetuin-A has any role in T1DM.

Relationship between asymmetric dimethylarginine in umbilical cord plasma and birth weight follows a U-shaped curve

Asymmetric dimethylarginine (ADMA) is a nonselective nitric oxide (NO) synthase inhibitor associated with cardiovascular and metabolic disorders. NO regulates placental blood flow, which plays an important role in fetal growth. Many epidemiological studies have disclosed that restricted fetal growth is associated with an increased risk of insulin resistance in adult life. We studied the relationship between ADMA in cord blood and birth size. Nine small for gestational age (SGA) and 32 appropriate for gestational age (AGA) infants were studied. Their cord plasma ADMA, insulin, insulin-like growth factor-1 (IGF-1), and adipocytokine levels were determined using enzyme-linked immunosorbent assays. The relationship between birth weight and ADMA levels followed a U-shaped curve rather than inverse linear associations expected over a full range of birth weight distribution. ADMA positively correlated with birth weight in the AGA group (p<0.001, R=0.590), and inversely correlated with birth weight in the SGA group (p<0.05, R=-0.741). ADMA inversely correlated with adiponectin (p<0.05, R=-0.289) and quantitative insulin sensitivity check index (QUICKI) (p<0.05, R=-0.294) in all subjects, and did not correlate with nitrogen oxides (NO_X). Insulin, IGF-1, leptin, adiponectin and QUICKI were lower in the SGA than the AGA group. Plasma ADMA levels in cord blood may be a marker of fetal growth and insulin resistance.

Asymmetric dimethylarginine is negatively correlated with hyperglycemia in children

Asymmetric dimethylarginine (ADMA) is a nonselective nitric oxide (NO) synthase inhibitor associated with cardiovascular and metabolic disorders. In several prospective and cross-sectional studies, ADMA has evolved as a marker of cardiovascular risk. However, there is limited information on this serum marker in young people, particularly in those with obesity, type 1 diabetes (DM1) and type 2 diabetes (DM2). We investigated ADMA concentrations in children and adolescents with hyperglycemia as compared with healthy age- and sex-matched individuals. The subjects were 21 simple obesity [male 13, female 8; aged 11.7±4.3 years], 18 with DM1 [male 4, female 14; aged 12.9±4.2 years, duration of disease 3.4±2.1 years], 10 with DM2 [male 5, female 5; aged 13.9±3.4 years, duration of disease 2.8±1.4 years] and 21 controls [male 12, female 9; aged 11.1±2.7 years]. ADMA levels were analyzed in a cross-sectional study. Concentrations of serum ADMA were determined using an enzyme-linked immunosorbent assay. Circulating levels of ADMA were significantly lower in subjects with DM1, DM2 or obesity. In all subjects, ADMA levels were inversely correlated with glycated hemoglobin A1c concentrations (r=-0.401, p=0.0003) and serum glucose levels (r=-0.341, p=0.0023). Low circulating ADMA levels are directly associated with glucose levels, suggesting that ADMA production is suppressed in childhood in order to compensate and protect vasculopathy due to hyperglycemia.

Evaluation of asymmetric dimethylarginine (ADMA) levels in children with growth hormone deficiency

OBJECTIVE

To investigate serum asymmetric dimethylarginine (ADMA) levels in children with isolated growth hormone deficiency (GHD) and to determine the effect of GH replacement therapy on these levels.

METHODS

31 patients diagnosed with isolated GHD and 29 age-and sex-matched healthy children were enrolled in the study. Height, weight and waist circumference were measured in all subjects. Fasting serum insulin-like growth factor-1 (IGF-1), IGF binding protein-3, glucose, insulin and lipid levels were evaluated. Serum ADMA levels were assessed using the enzyme-linked immunosorbent assay technique. The same evaluations were repeated on the 3rd and 6th months of treatment in 28 of the GHD cases.

RESULTS

There were no significant differences in ADMA levels between the patient and control groups [0.513±0.130 (0.291-0.820) µmol/L vs. 0.573±0.199 (0.241-1.049) µmol/L]. There was a positive correlation between serum ADMA and HbA1c levels in the control group. In the GHD cases, ADMA levels negatively correlated with high-density lipoprotein levels and positively correlated with low-density lipoprotein levels. There was also a significant increase in ADMA levels in patients receiving GH therapy compared to pre-treatment levels [serum ADMA level, 1.075±0.133 (0.796-1.303) µmol/L at the 3rd month and 0.923±0.121 (0.695-1.159) µmol/L at the 6th month of treatment]. There was a negative correlation between ADMA levels and homeostasis model assessment of insulin resistance values at the 6th month evaluation. There were no relationships between ADMA levels and age, sex, or pubertal state either before or during the treatment.

CONCLUSION

Serum ADMA levels were found to be similar in patients with GHD and in healthy children. However, serum ADMA levels showed a significant increase in GHD patients following GH replacement therapy.

Asymmetric dimethylarginine is associated with developmental programming of adult kidney disease and hypertension in offspring of streptozotocin-treated mothers

Diabetes mellitus complicates pregnancies, leading to diseases in adult life in the offspring. Asymmetric dimethylarginine (ADMA) is increased in diabetes mellitus, kidney disease, and hypertension. We tested whether maternal diabetes causes increased ADMA in rats, resulting in kidney disease and hypertension in the adult offspring, and whether these can be prevented by maternal citrulline supplementation. Newborn female and pregnant Sprague-Dawley rats were injected with streptozotocin (STZ), which made up the nSTZ and STZ models, respectively. For the STZ model, 4 groups of male offspring were killed at age 3 months: the control, STZ, and Cit and STZ+Cit (control and STZ rats treated with 0.25% l-citrulline solution, respectively) groups. The nSTZ rats had lower nephron numbers. The renal level of ADMA was higher in the nSTZ rats than in controls. The STZ group developed kidney injury, renal hypertrophy, and elevated blood pressure at the age of 12 weeks. These conditions were found to be associated with increased ADMA levels, decreased nitric oxide (NO) production, and decreased dimethylarginine dimethylaminohydrolase (DDAH) activity in the kidney. In addition, ADMA caused a nephron deficit in cultured rat metanephroi. Maternal citrulline supplementation prevented hypertension and kidney injury, increased the renal DDAH-2 protein level, and restored the levels of ADMA and NO in the STZ+Cit group. Reduced nephron number and increased ADMA contribute to adult kidney disease and hypertension in offspring of mothers with STZ-induced diabetes. Manipulation of the ADMA-NO pathway by citrulline supplementation may be a potential approach to prevent these conditions.

Associations between endogenous dimethylarginines and renal function in healthy children and adolescents

The structural isomer of asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), is eliminated almost entirely by urinary excretion and considered a sensitive index of glomerular filtration rate (GFR). However, reports on this relationship in healthy subjects younger than 18 years of age are rare. Therefore, our aim was to investigate relations between endogenous dimethylarginines and renal function indices in healthy children and adolescents. We studied 40 subjects aged 3–18 years free of coexistent diseases or subclinical carotid atherosclerosis. A serum creatinine-derived estimated GFR (eGFR) was calculated by the revised bedside Schwartz equation. L-arginine, ADMA and SDMA were measured by liquid chromatography-tandem mass spectrometry. Mean eGFR was 122 ± 22 (SD) mL/min per 1.73 m2. Creatinine and eGFR exhibited closer correlations with the SDMA/ADMA ratio (r = 0.64, p < 0.0001; r = −0.63, p < 0.0001, respectively) than with SDMA (r = 0.31, p = 0.05; r = −0.35, p = 0.03). Neither creatinine nor eGFR correlated with ADMA or L-arginine. Adjustment for age or height only slightly attenuated the associations between the SDMA/ADMA ratio and eGFR or creatinine. Our findings suggest the superiority of the SDMA/ADMA ratio over SDMA as a renal function index in healthy children. Thus, further studies are warranted to verify our preliminary results in a larger group of subjects below 18 years of age.

Cardiovascular risk in autoimmune disorders: role of asymmetric dimethylarginine

Mounting evidence indicates that cardiovascular events are a main cause of excessive mortality of autoimmune disorders like type I diabetes mellitus and rheumatic diseases. Inflammation and endothelial dysfunction, independent predictors to cardiovascular disease, are hallmarks of autoimmunity. Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, can cause or contribute to the inflammatory syndrome and endothelial dysfunction. Recently, elevated ADMA levels have been demonstrated in many autoimmune diseases, suggesting that ADMA might play an important role for the associated manifestations of cardiovascular disease. In the review, we discuss the role of ADMA in the excessive cardiovascular morbidity and mortality associated with autoimmune diseases.

Cardiovascular disease risk in young people with type 1 diabetes

Cardiovascular disease (CVD) is the most frequent cause of death in people with type 1 diabetes (T1D), despite modern advances in glycemic control and CVD risk factor modification. CVD risk identification is essential in this high-risk population, yet remains poorly understood. This review discusses the risk factors for CVD in young people with T1D, including hyperglycemia, traditional CVD risk factors (dyslipidemia, smoking, physical activity, hypertension), as well as novel risk factors such as insulin resistance, inflammation, and hypoglycemia. We present evidence that adverse changes in cardiovascular function, arterial compliance, and atherosclerosis are present even during adolescence in people with T1D, highlighting the need for earlier intervention. The methods for investigating cardiovascular risk are discussed and reviewed. Finally, we discuss the observational studies and clinical trials which have thus far attempted to elucidate the best targets for early intervention in order to reduce the burden of CVD in people with T1D.

Endogenous nitric oxide synthase inhibitors in the biology of disease: markers, mediators, and regulators?

The asymmetric methylarginines inhibit nitric oxide synthesis in vivo by competing with L-arginine at the active site of nitric oxide synthase. High circulating levels of asymmetric dimethylarginine predict adverse outcomes, specifically vascular events but there is now increasing experimental and epidemiological evidence that these molecules, and the enzymes that regulate this pathway, play a mechanistic role in cardiovascular diseases. Recent data have provided insight into the impact of altered levels of these amino acids in both humans and rodents, however these reports also suggest a simplistic approach based on measuring, and modulating circulating asymmetric dimethylarginine alone is inadequate. This review outlines the basic biochemistry and physiology of endogenous methylarginines, examines both the experimental and observational evidence for a role in disease pathogenesis, and examines the potential for therapeutic regulation of these molecules.