Hypouricemia linked to an overproduction of nitric oxide is an early marker of oxidative stress in female subjects with type 1 diabetes

Which patients with coronary artery disease should include oral nitrates on their discharge medication list?

BACKGROUND

Which patients with coronary artery disease (CAD) should have oral nitrates on their discharge medication list after coronary angiography (CAG)? To assess the relationship between oral nitrates included in the discharge medication list and major adverse cardiovascular events (MACEs) among CAD patients, we designed this retrospective cohort study.

METHODS

A total of 2979 CAD patients hospitalised in the Department of Cardiology, Affiliated Hospital of Jining Medical University from May 2013 to October 2015 were enrolled, grouped according to whether oral nitrates were included at discharge after CAG, and followed up for MACEs for a mean of 4.42 years after discharge. The primary endpoint was MACEs. Multivariate Cox proportional hazards models were used to analyses potential confounding factors. Stratified analysis was used to observe the relationship between oral nitrates and MACEs by different covariates.

RESULTS

The median follow-up time was 4.61 years, and 296 (9.94%) patients experienced MACEs. Multivariate Cox proportional hazards model analysis showed no association between oral nitrates on the discharge medication list and the occurrence of MACEs among patients with CAD (p > 0.05) after adjusting for some covariates, such as SYNTAX score (hazard ratio (HR): 1.18, 95% confidence interval (CI): 0.90-1.55, p = 0.2420). Stratified analysis revealed a higher incidence of MACEs among hypertensive patients prescribed oral nitrates at discharge (HR: 1.67, 95% confidence CI: 1.13-2.46, p = 0.0046). However, prescribing nitrates at discharge for patients with low uric acid levels increased the incidence of MACEs, which showed a possible trend towards significance (HR: 1.44, 95% CI: 0.99-2.09, p = 0.0525).

CONCLUSION

There was no association between oral nitrates included in the discharge medication list and the development of MACEs among patients with CAD after adjusting for some covariates, such as SYNTAX score. Oral nitrates after discharge for CAD patients combined with hypertension increased the occurrence of MACEs. Oral nitrates after discharge for CAD patients combined with low uric acid levels may increase theoccurrence of MACEs, and close monitoring for any adverse events is recommended.

Serum uric acid levels and health outcomes in CKD: a prospective cohort study

BACKGROUND

Hyperuricemia is prevalent in individuals with chronic kidney disease (CKD). Elevated serum uric acid (SUA) concentrations have been considered an independent risk factor for the onset of CKD. However, the relationship between SUA concentrations and long-term health outcomes among patients with CKD remains unclear.

METHODS

We performed a prospective cohort study with nationally representative sample to investigate the relationship between SUA concentrations and mortality risk including all-cause, cardiovascular disease (CVD) and cancer mortality, among patients with CKD. The weighted restricted cubic spline analyses combined with the multivariate-adjusted Cox proportional hazard models were used to test the nonlinearity of relationship.

RESULTS

The 6642 patients participating in National Health and Nutrition Examination Survey 1999-2018 were enrolled. During 656 885 person-months of follow-up time, 2619 all-cause deaths were recorded, including 1030 CVD deaths and 458 cancer deaths. Our study presented J-shaped non-linear relationships between SUA concentrations and all-cause and CVD mortality with inflection points at 311.65 μmol/L and 392.34 μmol/L, respectively. When SUA concentration was higher than those inflection points, every increase of 50 μmol/L SUA was associated with 11.7% and 17.0% greater multivariable-adjusted hazard ratio of all-cause and CVD mortality, respectively. In addition, a negative linear correlation with cancer mortality was detected.

CONCLUSION

These findings suggested that maintaining appropriate SUA concentrations may improve long-term health outcomes among CKD patients. The corresponding inflection points of J-shaped non-linear relationships were 311.65 and 392.34 μmol/L for all-cause and CVD mortality. Further clinical trials are required to investigate uric acid-lowering targets.

Predictive risk markers in alcoholism

The medical disorders of alcoholism rank among the leading public health problems worldwide and the need for predictive and prognostic risk markers for assessing alcohol use disorders (AUD) has been widely acknowledged. Early-phase detection of problem drinking and associated tissue toxicity are important prerequisites for timely initiations of appropriate treatments and improving patient's committing to the objective of reducing drinking. Recent advances in clinical chemistry have provided novel approaches for a specific detection of heavy drinking through assays of unique ethanol metabolites, phosphatidylethanol (PEth) or ethyl glucuronide (EtG). Carbohydrate-deficient transferrin (CDT) measurements can be used to indicate severe alcohol problems. Hazardous drinking frequently manifests as heavy episodic drinking or in combinations with other unfavorable lifestyle factors, such as smoking, physical inactivity, poor diet or adiposity, which aggravate the metabolic consequences of alcohol intake in a supra-additive manner. Such interactions are also reflected in multiple disease outcomes and distinct abnormalities in biomarkers of liver function, inflammation and oxidative stress. Use of predictive biomarkers either alone or as part of specifically designed biological algorithms helps to predict both hepatic and extrahepatic morbidity in individuals with such risk factors. Novel approaches for assessing progression of fibrosis, a major determinant of prognosis in AUD, have also been made available. Predictive algorithms based on the combined use of biomarkers and clinical observations may prove to have a major impact on clinical decisions to detect AUD in early pre-symptomatic stages, stratify patients according to their substantially different disease risks and predict individual responses to treatment.

Transdermal delivery of allopurinol to acute hyperuricemic mice via polymer microneedles for the regulation of serum uric acid levels

Allopurinol (AP) is widely used to treat hyperuricemia which may cause severe side effects upon oral administration. Alternative means for the treatment of hyperuricemia are demanded to simultaneously facilitate drug absorption, patient compliance, and fewer side effects. In this study, a new polymer microneedle (MN) system was developed for the transdermal delivery of AP to acute hyperuricemic mice. This study aims to achieve the controllable regulation of serum uric acid (SUA) levels with fewer side effects compared with oral administration. The matrix of polymer MNs consisted of polyvinylpyrrolidone (PVP) and polycaprolactone (PCL), in which the rapid dissolution of PVP offers a rapid dissolution of AP into the blood and the biodegradability of PCL resulting in a sustainable drug release behavior. An in vivo study demonstrated that the AP-loaded MN system can effectively reduce the SUA levels as oral administration with lower side effects, which will be conducive to reducing the adverse reactions and improving the bioavailability of AP. This MN-mediated strategy can facilitate transcutaneous hyperuricemia treatment and provide a new alternative for the exploration of clinical treatment of hyperuricemia and improvement of patient compliance.

Predictive model of diabetes mellitus in patients with idiopathic inflammatory myopathies

Objectives

Cardiovascular diseases are the common cause of death in patients with idiopathic inflammatory myopathies (IIMs). Diabetes mellitus was associated with higher cardiovascular mortality, but few studies focused on the risk of diabetes mellitus in IIMs patients. Our study is aimed at developing a predictive model of diabetes mellitus in IIMs patients.

Methods

A total of 354 patients were included in this study, of whom 35 (9.9%) were diagnosed as new-onset diabetes mellitus. The predictive nomogram was drawn based on the features selected by least absolute shrinkage and selection operator (LASSO) regression, univariate logistic regression, multivariable logistic regression, and clinical relationship. The discriminative capacity of the nomogram was assessed by C-index, calibration plot, and clinical usefulness. The predictive model was verified by the bootstrapping validation.

Results

The nomogram mainly included predictors such as age, gender, hypertension, uric acid, and serum creatinine. This predictive model demonstrated good discrimination and calibration in primary cohort (C-index=0.762, 95% CI: 0.677-0.847) and validation cohort (C-index=0.725). Decision curve analysis indicated that this predictive model was clinically useful.

Conclusions

Clinicians can assess the risk of diabetes mellitus in IIMs patients by using this prediction model, and preventive measures should be taken early for high-risk patients, ultimately reducing the adverse cardiovascular prognosis.

Creation of an adequate animal model of hyperuricemia (acute and chronic hyperuricemia); study of its reversibility and its maintenance

AIM

Hyperuricemia is defined by the European Rheumatology Society as a uric acid level greater than 6 mg/dl (60 mg/l or 360 μmol/l). Our goal was to evaluate the hypouricemic effect of nettle. For this reason, we have first of all try to create an hyperuricemic animal model which is very suitable because at the level of literature there is not an exact model, there are many models and our objective is to set an adequate model.

MATERIALS AND METHODS

An attempt has been made to test acute and chronic hyperuricemia by varying the duration and method of induction of potassium oxonate. Similarly, attempts have been made to induce chronic hyperuricemia through an animal and vegetable diet. The reversibility of hyperuricemia was tested with a maintenance protocol.

KEY FINDINGS

For the creation of the hyperuricemia model, it has been shown that acute hyperuricemia cannot be induced by short administration of potassium oxonate and persistent chronic hyperuricemia can be induced only after daily administration of oxonate of potassium by intraperitoneal injection for 15 days. Indeed, hyperuricemia was reversible after stopping the administration of potassium oxonate. The high-purine diet is also capable of inducing chronic hyperuricemia but to a less extent.

SIGNIFICANCE

After creating an adequate model of hyperuricemia while setting the dose of potassium oxonate, route of administration and duration. A maintenance protocol was followed which subsequently made it possible to deduce that the daily administration of potassium oxonate must be continued to maintain the hyperuricemia.

Serum uric acid and mortality thresholds among men and women in the Irish health system: A cohort study

BACKGROUND

Elevation of serum uric acid (SUA) is associated with increased mortality; however, controversy exists regarding the nature of the relationship and differences between men and women. We explored relationships of SUA levels with all-cause mortality in a large cohort of patients within the Irish health system.

METHODS

A retrospective cohort study of 26,525 participants was conducted using data from the National Kidney Disease Surveillance System. SUA was modelled in increments of 59.48 µmol/L (1 mg/dL), Cox's proportional hazards model estimated hazard ratios (HRs) and 95% Confidence Intervals (CI), median lifetimes were also computed separately for men and women. Mortality patterns were further explored using penalised splines.

RESULTS

There were 1,288 (4.9%) deaths over a median follow-up of 5.1 years. In men, the risk of mortality was greatest for the lowest (<238 µmol/L) and highest (>535 µmol/L) categories [HR 2.35 (1.65-3.14) and HR 2.52 (1.87-3.29) respectively]; the corresponding median lifetimes for men were reduced by 9.5 and 11.7 years respectively compared to the referent. In women, mortality risks were elevated for SUA >416 mol/L [HR 1.69 (1.13-2.47) and beyond; the corresponding median lifetime for women were reduced by 5.9 years compared to the referent. Spline analysis revealed a U-shaped association between SUA and mortality in men, while for women, the pattern of association was J-shaped.

CONCLUSION

Mortality patterns attributed to SUA differ between men and women. Optimal survival was associated with SUA concentrations of 304-454 µmol/L for men and < 409 µmol/L for women.

Circulating biomarkers of nitric oxide bioactivity and impaired muscle vasoreactivity to exercise in adults with uncomplicated type 1 diabetes

AIMS/HYPOTHESIS

Early compromised endothelial function challenges the ability of individuals with type 1 diabetes to perform normal physical exercise. The exact mechanisms underlying this vascular limitation remain unknown, but may involve either formation or metabolism of nitric oxide (NO), a major vasodilator, whose activity is known to be compromised by oxidative stress.

METHODS

Muscle microvascular reactivity (near-infrared spectroscopy) to an incremental exhaustive bout of exercise was assessed in 22 adults with uncomplicated type 1 diabetes (HbA_1c 64.5 ± 15.7 mmol/mol; 8.0 ± 1.4%) and in 21 healthy individuals (18-40 years of age). NO-related substrates/metabolites were also measured in the blood along with other vasoactive compounds and oxidative stress markers; measurements were taken at rest, at peak exercise and after 15 min of recovery. Demographic characteristics, body composition, smoking status and diet were comparable in both groups.

RESULTS

Maximal oxygen uptake was impaired in individuals with type 1 diabetes compared with in healthy participants (35.6 ± 7.7 vs 39.6 ± 6.8 ml min^-1 kg^-1, p < 0.01) despite comparable levels of habitual physical activity (moderate to vigorous physical activity by accelerometery, 234.9 ± 160.0 vs 280.1 ± 114.9 min/week). Compared with non-diabetic participants, individuals with type 1 diabetes also displayed a blunted exercise-induced vasoreactivity (muscle blood volume at peak exercise as reflected by ∆ total haemoglobin, 2.03 ± 5.82 vs 5.33 ± 5.54 μmol/l; interaction 'exercise' × 'group', p < 0.05); this was accompanied by lower K⁺ concentration (p < 0.05), reduced plasma L-arginine (p < 0.05)-in particular when HbA_1c was high (mean estimation: -4.0, p < 0.05)-and lower plasma urate levels (p < 0.01). Nonetheless, exhaustive exercise did not worsen lipid peroxidation or other oxidative stress biomarkers, and erythrocytic enzymatic antioxidant resources were mobilised to a comparable extent in both groups. Nitrite and total nitrosation products, which are potential alternative NO sources, were similarly unaltered. Graphical abstract CONCLUSIONS/INTERPRETATION: Participants with uncomplicated type 1 diabetes displayed reduced availability of L-arginine, the essential substrate for enzymatic nitric oxide synthesis, as well as lower levels of the major plasma antioxidant, urate. Lower urate levels may reflect a defect in the activity of xanthine oxidase, an enzyme capable of producing NO from nitrite under hypoxic conditions. Thus, both canonical and non-canonical NO production may be reduced. However, neither of these changes exacerbated exercise-induced oxidative stress.

TRIAL REGISTRATION

clinicaltrials.gov NCT02051504.

Rule of UA on Cardiac Myocytes Uric Acid Differently Influence the Oxidative Damage Induced by Acute Exposure of High Level of Glucose in Chicken Cardiac Myocytes

Background: Uric acid (UA) is a potent scavenger of oxidants in mammalian and avian species. In humans, hyperglycemia with simultaneous hyperuricemia may exert additional damage to the cardiovascular system. Chickens naturally have hyperglycemia (10.1–11.0 mmol/L) and hyperuricemia (100–900 μmol/L), which makes them an interesting model.

Methods: The aim of this study was to investigate the effects of UA on the oxidative damage induced by acute exposure of high level of glucose in chicken cardiac myocytes.

Results: Cell viability and the concentrations of thiobarbituric acid reactive substance (TBARS) were decreased by glucose treatment in a dose- and time-dependent manner. After acute exposure to high level of glucose (300 mM), a moderate level of UA (300 μM) increased cell viability and reduced TBARS and glutathione (GSH) content. Compared to the control or to independent high glucose (300 mM) or UA (1,200 μM) treatment, the concurrent treatment of high glucose and high UA significantly increased the TBARS, protein carbonyl contents, and ROS concentration, whereas it decreased the cell viability, superoxide dismutase (SOD) activity, and GSH content. In the presence of high glucose and UA, the nucleic protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2) was decreased and the mRNA levels of the genes cat, sod1, sod2, gss, and gclc were downregulated.

Conclusion: In conclusion, acute exposure of high level of glucose induced oxidative damage in the cardiac myocytes of chicken. The present result suggests that an adequate level of uric acid is helpful in alleviating the acute oxidative damage that is induced by high glucose, whereas the inhibition of the Nrf2 pathway by a high level of uric acid may render the cardiac myocytes more vulnerable to suffering from oxidative damage.

Supplementary Nitric Oxide Donors and Exercise as Potential Means to Improve Vascular Health in People with Type 1 Diabetes: Yes to NO?

Type 1 diabetes (T1D) is associated with a greater occurrence of cardiovascular pathologies. Vascular dysfunction has been shown at the level of the endothelial layers and failure to maintain a continuous pool of circulating nitric oxide (NO) has been implicated in the progression of poor vascular health. Biochemically, NO can be produced via two distinct yet inter-related pathways that involve an upregulation in the enzymatic activity of nitric oxide synthase (NOS). These pathways can be split into an endogenous oxygen-dependent pathway i.e., the catabolism of the amino acid L-arginine to L-citrulline concurrently yielding NO in the process, and an exogenous oxygen-independent one i.e., the conversion of exogenous inorganic nitrate to nitrite and subsequently NO in a stepwise fashion. Although a body of research has explored the vascular responses to exercise and/or compounds known to stimulate NOS and subsequently NO production, there is little research applying these findings to individuals with T1D, for whom preventative strategies that alleviate or at least temper vascular pathologies are critical foci for long-term risk mitigation. This review addresses the proposed mechanisms responsible for vascular dysfunction, before exploring the potential mechanisms by which exercise, and two supplementary NO donors may provide vascular benefits in T1D.

Effect of magnesium on reducing the UV-induced oxidative damage in marrow mesenchymal stem cells

Oxidative stress could cause damage to lipids, proteins and DNA, which is induced by the imbalance between the production of reactive oxygen species (ROS) and the biological system ability to counteract or detoxify their harmful effects. The oxidative stress damage significantly contributes to a number of diseases. Magnesium (Mg) is endowed with a novel function of removing excess ROS by releasing H₂ during the degradation. In this study, in order to explore the property of anti-oxidative damage of Mg metal, rat bone marrow mesenchymal stem cells (MSCs) oxidative damaged by ultraviolet (UV) radiation was employed to co-culture with Mg metal. The effect of Mg metal on the response of antioxidant enzymes and mitochondria in MSCs was studied. We found that Mg metal could reduce the cellular oxidative stress damage and elevate the activities of antioxidant enzymes to maintain redox homeostasis. In addition, Mg metal could reduce the risk of UV-induced cell apoptosis by increasing the ratio of Bcl-2/Bax, elevating the mitochondrial membrane potential and blocking the release of cytochrome c. This finding showed Mg metal might have the potential for treating diseases caused by oxidative stress damage. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1253-1263, 2019.

Red Blood Cell Distribution Width Is Associated with Carotid Atherosclerosis in People with Type 2 Diabetes

AIMS

Red cell distribution width (RDW) has been shown to be associated with cardiovascular diseases (CVD). The relationship between RDW and carotid intima-media thickness (C-IMT), a marker of subclinical atherosclerosis, has been inconsistent in subjects with cardiovascular risk factors. In this study, we investigated the relationship between RDW and carotid atherosclerosis in people with type 2 diabetes.

METHODS

Four hundred sixty-nine people with type 2 diabetes without history of cardiovascular or cerebrovascular diseases were enrolled. Anthropometric measures and various biochemical parameters including RDW were assessed. Ultrasonographic measurement of carotid intima-media thickness was used to evaluate subclinical atherosclerosis.

RESULTS

The participants were stratified into 3 groups according to RDW. The C-IMT increased gradually according to RDW tertiles (lowest, second, highest RDW tertiles; 0.740 ± 0.120, 0.772 ± 0.138, and 0.795 ± 0.139, respectively; p < 0.01). Multiple regression analysis and multivariate logistic regression analysis revealed that RDW was associated with C-IMT in people with type 2 diabetes, and it remained significant after control for various cardiovascular risk factors including body mass index, blood pressure, insulin resistance, and smoking status in multivariate logistic regression analysis.

CONCLUSION

RDW is associated with subclinical atherosclerosis assessed by carotid IMT after control of various covariates in people with type 2 diabetes without cardiovascular or cerebrovascular diseases.

Uric Acid Level Has a U-shaped Association with Clinical Outcomes in Patients with Vasospastic Angina

No data are available on the association of serum uric acid and vasospastic angina (VSA) which has endothelial dysfunction as a possible pathophysiologic mechanism. Low uric acid level might cause adverse outcomes in VSA in connection with endothelial dysfunction. We enrolled 818 VSA patients whose uric acid level was measured at admission. Patients were categorized according to tertiles of uric acid level: group I, ≤ 4.8 mg/dL; group II, 4.9-5.9 mg/dL; and group III, ≥ 6.0 mg/dL. Primary outcome was major adverse cardiac events (MACEs), defined as a composite of cardiac death, acute myocardial infarction (MI), ischemic stroke, coronary revascularization, and rehospitalization for angina. Median follow-up duration was 49.2 months. Median uric acid values were 4.1 mg/dL for group I, 5.4 mg/dL for group II, and 6.7 mg/dL for group III. In the overall population, group II had a significantly lower incidence of MACE compared to group I (47 [17.1%] vs. 66 [24.6%]; hazard ratio [HR], 1.52; 95% confidence interval [CI], 1.02-2.26; P = 0.040) and a tendency of lower incidence of MACEs compared to Group III (47 [17.1%] vs. 62 [22.5%]; HR, 1.44; 95% CI, 0.98-2.13; P = 0.067). Among group I patients, those who received nitrates had a higher incidence of MACEs than those without nitrate therapy (P < 0.001). Low uric acid level was associated with adverse clinical outcomes, while high uric acid level had a trend toward an increase in it. Use of nitrate in patients with low uric acid level might have adverse effects on clinical outcomes of VSA.

Depletion of Uric Acid Due to SLC22A12 (URAT1) Loss-of-Function Mutation Causes Endothelial Dysfunction in Hypouricemia

BACKGROUND

Uric acid (UA) serves as an antioxidant in vascular endothelial cells. UA transporter 1 (URAT1) encoded by SLC22A12 is expressed in the kidney and vessels and its loss of function causes hypouricemia. The purpose of this study was to examine whether there is any endothelial dysfunction in patients with hypouricemia.

METHODS AND RESULTS

Twenty-six patients with hypouricemia (<2.5 mg/dl) and 13 healthy control subjects were enrolled. Endothelial function was evaluated using flow-mediated dilation (FMD). mRNA of UA transporters expressed in cultured human umbilical endothelial cells (HUVEC) was detected on RT-PCR. There was a positive correlation between FMD and serum UA in the hypouricemia group. URAT1 loss-of-function mutations were found in the genome of 21 of 26 patients with hypouricemia, and not in the other 5. In the hypouricemia groups, serum UA in homozygous and compound heterozygous patients was significantly lower than in other groups, suggesting that severity of URAT1 dysfunction may influence the severity of hypouricemia. Thirteen of 16 hypouricemia subjects with homozygous and compound heterozygote mutations had SUA <0.8 mg/dl and their FMD was lower than in other groups. HUVEC do not express mRNA of URAT1, suggesting the null role of URAT1 in endothelial function.

CONCLUSIONS

Depletion of UA due to SLC22A12/URAT1 loss-of-function mutations causes endothelial dysfunction in hypouricemia patients.

Oxidative stress in diabetes: implications for vascular and other complications

In recent decades, oxidative stress has become a focus of interest in most biomedical disciplines and many types of clinical research. Increasing evidence shows that oxidative stress is associated with the pathogenesis of diabetes, obesity, cancer, ageing, inflammation, neurodegenerative disorders, hypertension, apoptosis, cardiovascular diseases, and heart failure. Based on these studies, an emerging concept is that oxidative stress is the “final common pathway” through which the risk factors for several diseases exert their deleterious effects. Oxidative stress causes a complex dysregulation of cell metabolism and cell–cell homeostasis; in particular, oxidative stress plays a key role in the pathogenesis of insulin resistance and β-cell dysfunction. These are the two most relevant mechanisms in the pathophysiology of type 2 diabetes and its vascular complications, the leading cause of death in diabetic patients.

Serum uric acid is a GFR-independent long-term predictor of acute and chronic renal insufficiency: the Jerusalem Lipid Research Clinic cohort study

BACKGROUND

Kidney disease is commonly accompanied by hyperuricemia. However, the contribution of serum uric acid (SUA) to kidney injury is debated. Our objective was to assess the long-term prediction of renal failure by SUA.

METHODS

Visit 2 participants in the Jerusalem Lipid Research Clinic cohort with normal baseline kidney function were followed for 24-28 years. SUA levels were assessed for associations with acute renal failure (ARF) and chronic renal failure (CRF) as defined by hospital discharge records, and mortality, ascertained through linkage with the national population registry.

RESULTS

Among 2449 eligible participants (1470 men, 979 women aged 35-78 years in 1976-79), SUA was positively linked with male sex, serum creatinine and components of the metabolic syndrome but was lower in smokers and in diabetic subjects. The 22- to 25-year incidence of hospital-diagnosed kidney failure (145 first events, 67% CRF) and the 24- to 28-year mortality (587 events) were higher in subject with hyperuricemia (>6.5 mg/dL in men and >5.3 mg/dL in women, reflecting the upper quintiles), independent of baseline kidney function and covariates. Hyperuricemia conferred adjusted hazard ratios of 1.36 (P = 0.003), 2.14 (P < 0.001) and 2.87 (P = 0.003) for mortality, CRF and ARF, respectively.

CONCLUSIONS

SUA predicts renal failure incidence and all-cause mortality independently of demographic and clinical covariates. These results lend support to the undertaking of clinical trials to examine the effect of uric acid-lowering strategies on kidney outcomes.

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

OBJECTIVE

Although high levels of asymmetric dimethylarginine (ADMA) are associated with an increased risk for vasculopathy in adults, elevated ADMA concentrations also have been found in healthy young children. Patients with diabetes mellitus type 1 (DM1) are at risk for vasculopathy, and because the function of ADMA in the development of vascular symptoms is incompletely understood, we investigated ADMA concentrations in pediatric patients with DM1 compared with healthy age- and sex-matched individuals.

STUDY DESIGN

This cross-sectional study included 85 pediatric patients with DM1 and 89 age- and sex-matched healthy controls.

RESULTS

ADMA concentrations were significantly lower in the patients with DM1 and were inversely correlated with hemoglobin A1c concentrations.

CONCLUSIONS

Besides its vasoprotective function, nitric oxide itself may exert oxidative stress by generating free radicals. In these circumstances, ADMA would protect the system from nitric oxide overproduction and perpetuation of oxidative stress. This theory is supported by the physiologically higher ADMA concentrations in healthy children. Thus, low ADMA concentrations in children with DM1 may be an indicator of impaired protection against oxidative stress.

Role of asymmetric-dimethyl-L-arginine (ADMA) and nitrite/nitrate (NOx) in the pathogenesis of oxidative stress in female subjects with uncomplicated type 1 diabetes mellitus

AIMS

To explore the role of asymmetric-dimethyl-L-arginine (ADMA), an endogenous nitric oxide synthetases (NOS) inhibitor, and nitrite/nitrate (NOx) in the pathogenesis of oxidative stress in early stages of type 1 diabetes mellitus.

METHODS

We measured in 99 female subjects with uncomplicated type 1 diabetes (duration disease <10 years) and in 44 sex-matched controls (comparable for age, smoking habit, diet and physical activity) plasma levels of NOx, glycosylated haemoglobin (HbA1c), glucose, uric acid, total cholesterol, high density lipoprotein (HDL) cholesterol, triglycerides and serum ADMA.

RESULTS

Type 1 diabetic subjects have higher levels of glycemia, HbA1c, LDL cholesterol and NOx, but lower ADMA and serum uric acid (UA), compared with the control group; no further differences were found. A significant linear and inverse correlation was found between NOx and ADMA levels (R(2)=0.237, p<0.001).

CONCLUSIONS

This study suggests a reduced ADMA inhibition of NOS as possible mechanism involved in the pathogenesis of oxidative stress in female subjects with a short duration and uncomplicated type 1 diabetes.

Bibliography. Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 February 2008 and 31 January 2009 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.

Gender-dependent impacts of body mass index and moderate alcohol consumption on serum uric acid--an index of oxidant stress status?

Uric acid seems to be causally involved in a variety of medical disorders involving oxidative stress. Although alcohol abuse and obesity are known to increase serum uric acid, the interactions between moderate drinking, adiposity, and uric acid metabolism have remained poorly understood. We examined serum uric acid concentrations from 2062 apparently healthy volunteers (970 men, 1092 women) reporting either no alcohol (abstainers) or <40 g of ethanol consumption per day (moderate drinkers). The study population was further classified according to BMI as follows: <19 (underweight), 19-25 (normal weight), 25-30 (overweight), and >30 (obese). Serum uric acid concentrations in male moderate drinkers were significantly higher, and in females they were lower, than in the corresponding groups of abstainers. In the BMI-based subgroups, the highest concentrations were found in those who were overweight or obese. Significant two-factor interactions occurred between gender and drinking status (p<0.001) and between gender and BMI (p<0.02). Serum uric acid also correlated with indices of hepatocellular health (GGT, ALT, AST). The data indicate distinct gender-dependent impacts of alcohol consumption and BMI on serum uric acid. These findings should be applicable to the assessment of oxidative stress status and associated morbidity in alcohol consumers and individuals with excess body weight.