Changes in insulin and lipid metabolism in males with asymptomatic hyperuricaemia

Uric acid in metabolic syndrome: Does uric acid have a definitive role?

Increased serum uric acid (SUA) levels are commonly seen in patients with metabolic syndrome and are widely accepted as risk factors for hypertension, gout, non-alcoholic fatty liver disease, chronic kidney disease (CKD), and cardiovascular diseases. Although some ambiguity for the exact role of uric acid (UA) in these diseases is still present, several pathophysiological mechanisms have been identified such as increased oxidative stress, inflammation, and apoptosis. Accumulating evidence in genomics enlightens genetic variabilities and some epigenetic changes that can contribute to hyperuricemia. Here we discuss the role of UA within metabolism and the consequences of asymptomatic hyperuricemia while providing newfound evidence for the associations between UA and gut microbiota and vitamin D. Increased SUA levels and beneficial effects of lowering SUA levels need to be elucidated more to understand its complicated function within different metabolic pathways and set optimal target levels for SUA for reducing risks for metabolic and cardiovascular diseases.

Upregulation of Uric Acid Production and Caspase 3 Signalling Mediates Rohypnol-Induced Cardiorenal Damage

The global prevalence of illicit drug use is on the increase with attendant complications like cardiorenal collapse. One such substance of abuse is rohypnol. Despite its ban in most countries, it remains a popular substance of abuse. Whether or not rohypnol induces cardiorenal injury and the associated mechanism is yet to be elucidated. Therefore, the present study investigated the effect of rohypnol on cardiorenal integrity and functions, and glucolipid metabolism. Forty-eight male Wistar rats randomized into six groups (n = 8/group) received (per os) vehicle, low-dose (2 mg/kg) and high-dose (4 mg/kg) rohypnol once daily for twenty eight days, with or without a cessation period. Data revealed that rohypnol exposure irreversibly caused insulin resistance, hyperglycaemia, and dyslipidaemia. This was accompanied by reduced cardiorenal mass and impaired cardiorenal cytoarchitecture and function. Furthermore, rohypnol treatment promoted oxidative stress, inflammation, genotoxicity, and decreased cardiorenal activities of Na⁺-K⁺-ATPase, Ca²⁺-ATPase, and Mg²⁺-ATPase. These alterations were associated with enhanced uric acid generation and caspase 3 activity in the cardiorenal complex. Thus, this study reveals that rohypnol exposure triggers cardiorenal toxicity with incident insulin resistance, glucolipid and cardiorenal proton pump dysregulation, altered redox state, and inflammation via enhancement of uric acid generation and caspase 3-dependent mechanism.

Xanthine Oxidoreductase-Mediated Superoxide Production Is Not Involved in the Age-Related Pathologies in Sod1-Deficient Mice

Reactive oxygen species (ROS) metabolism is regulated by the oxygen-mediated enzyme reaction and antioxidant mechanism within cells under physiological conditions. Xanthine oxidoreductase (XOR) exhibits two inter-convertible forms (xanthine oxidase (XO) and xanthine dehydrogenase (XDH)), depending on the substrates. XO uses oxygen as a substrate and generates superoxide (O2•-) in the catalytic pathway of hypoxanthine. We previously showed that superoxide dismutase 1 (SOD1) loss induced various aging-like pathologies via oxidative damage due to the accumulation of O2•- in mice. However, the pathological contribution of XO-derived O2•- production to aging-like tissue damage induced by SOD1 loss remains unclear. To investigate the pathological significance of O2•- derived from XOR in Sod1-/- mice, we generated Sod1-null and XO-type- or XDH-type-knock-in (KI) double-mutant mice. Neither XO-type- nor XDH-type KI mutants altered aging-like phenotypes, such as anemia, fatty liver, muscle atrophy, and bone loss, in Sod1-/- mice. Furthermore, allopurinol, an XO inhibitor, or apocynin, a nicotinamide adenine dinucleotide phosphate oxidase (NOX) inhibitor, failed to improve aging-like tissue degeneration and ROS accumulation in Sod1-/- mice. These results showed that XOR-mediated O2•- production is relatively uninvolved in the age-related pathologies in Sod1-/- mice.

Hemoglobin concentration is associated with the incidence of metabolic syndrome

BACKGROUND

An association between hemoglobin and metabolic syndrome (MetS) has been reported. However, the relationships between hemoglobin and individual MetS components remain unclear. Therefore, we investigated these associations at baseline and at the 3-year follow-up.

METHODS

We enrolled 9960 middle-aged and elderly subjects (6726 women and 3234 men) and performed a 3-year follow-up cohort study. All subjects completed a questionnaire and underwent anthropometric measurements and laboratory tests. Logistic regression models were developed to assess the association between hemoglobin and MetS and its components.

RESULTS

MetS was present in 45.1% of women and 41.4% of men at baseline. The hemoglobin concentration was positively correlated with SBP, DBP, TGs, WC, FPG, insulin, HOMA-IR, BMI and uric acid (p < 0.05). The mean hemoglobin concentration was higher in subjects with hypertension, high TGs, abdominal obesity or elevated FPG (p < 0.01). At follow-up, elevated hemoglobin correlated with an increased incidence and ORs for MetS, high TGs, low HDL-c, hyperuricemia and NAFLD but not abdominal obesity, BP or FPG in women. Increased hemoglobin corresponded with an increased incidence and ORs for MetS, abdominal obesity, low HDL-c, hyperuricemia and NAFLD but not BP, high TGs or FPG in men.

CONCLUSIONS

Hemoglobin may play a role in predicting new-onset MetS in both women and men. Hemoglobin was notably correlated with future risk of high TGs, low HDL-c, hyperuricemia, and NAFLD among women and abdominal obesity, low HDL-c, hyperuricemia, and NAFLD among men.

Codeine exerts cardiorenal injury via upregulation of adenine deaminase/xanthine oxidase and caspase 3 signaling

AIMS

Codeine treatment has been shown to be associated with glucolipid deregulation, though data reporting this are inconsistent and the mechanisms are not well understood. Perturbation of glutathione-dependent antioxidant defense and adenosine deaminase (ADA)/xanthine oxidase (XO) signaling has been implicated in the pathogenesis of cardiometabolic disorders. We thus, hypothesized that depletion of glutathione contents and upregulation of ADA/XO are involved in codeine-induced glucolipid deregulation. The present study also investigated whether or not codeine administration would induce genotoxicity and apoptosis in cardiac and renal tissues.

MATERIALS AND METHODS

Male New Zealand rabbits received per os distilled water or codeine, either in low dose (4 mg/kg) or high dose (10 mg/kg) for 6 weeks.

KEY FINDINGS

Codeine treatment led to reduced absolute and relative cardiac and renal mass independent of body weight change, increased blood glucose, total cholesterol (TC), triglycerides (TG), and low-density lipoprotein (LDL-C), as well as increased atherogenic indices and triglyceride-glucose index (TyG). Codeine administration significantly increased markers of cardiac and renal injury, as well as impaired cardiorenal functions. Codeine treatment also resulted in increased cardiac and renal malondialdehyde, Advanced Glycation Endproducts (AGE) and 8-hydroxydeoxyguanosine (8-OH-dG), and myeloperoxidase (MPO), ADA, XO, and caspase 3 activities. These observations were accompanied by impaired activities of cardiac and renal proton pumps.

SIGNIFICANCE

Findings of this study demonstrate that upregulation of ADA/XO and caspase 3 signaling are, at least partly, contributory to the glucolipid deregulation and cardiorenal injury induced by codeine.

Association Between Hyperuricemia and Acute Ischemic Stroke in Patients at a Tertiary Care Hospital

Introduction

Stroke is the most debilitating of neurologic diseases. The rationale of the current study was to determine the association between hyperuricemia and ischemic stroke to establish a local perspective.

Methods

A total of 148 patients at a tertiary care hospital in Pakistan who fulfilled the inclusion criteria were enrolled in the study and then equally distributed into two study groups consisting of cases and controls (n = 74 in each group). In this study, there were 36 (48.6%) participants in the case group with hyperuricemia and ischemic stroke and 18 (24.3%) participants in the control group with hyperuricemia. The mean and standard deviations were computed for quantitative variables such as age, body mass index (BMI), and duration of stroke. Frequencies and percentages for the qualitative variables such as gender, hypertension, type 2 diabetes (T2D), dyslipidemia, smoking status, socioeconomic status, educational level, and hyperuricemia were calculated. The chi-square test was applied to compare both groups, with p ≤ 0.05 indicating significance. The odds ratio was also calculated to determine the association between case and control. Effect modifiers were controlled through stratification of age, gender, BMI, duration of stroke, hypertension, T2D, dyslipidemia, socioeconomic status, educational level, and smoking status to determine the effect of these on outcome variables. A post-stratification chi-square test was applied, with p ≤ 0.05 indicating statistical significance.

Results

In our study, stratification of hyperuricemia into cases and controls was performed for age, gender, T2D, hypertension, dyslipidemia, smoking status, socioeconomic status, and educational status. The maximum results were significant, with high strength of association between both groups. In the case group, the frequency of elevated uric acid was significantly higher than that of the control group. A comparison of hyperuricemia indicated p = 0.002, with an odds ratio of 2.95, which showed that elevated uric acid could be taken as a predictor of ischemic stroke. The uric acid level was significantly higher in men than in women. Additionally, hyperuricemia was associated with dyslipidemia. In patients with ischemic stroke, there was a significant association between serum uric acid level and T2D, hypertension, and smoking.

Conclusions

This study showed that the prevalence of hyperuricemia in patients with ischemic stroke was significantly higher as compared to the healthy population. Hyperuricemia can be considered as a risk factor for ischemic stroke because of its high prevalence in ischemic stroke patients. Our study explored the relationship between stroke and hyperuricemia and enabled increased understanding for caregivers so that effective management plans can be formulated for patients with ischemic stroke to prevent adverse outcomes.

Purine Metabolite Signatures and Type 2 Diabetes: Innocent Bystanders or Actionable Items?

PURPOSE OF REVIEW

This article reviews evidence linking cardiometabolic conditions with changes in purine metabolites, including increased serum uric acid (sUA), and discusses intervention studies that investigated the therapeutic relevance of these associations.

RECENT FINDINGS

Metabolic and epidemiological findings support a correlation between sUA and circulating levels of other purines with insulin resistance (IR) and risk factors for cardiovascular disease (CVD). In addition, increased activity of xanthine oxidoreductase (XOR), the rate-limiting enzyme for UA production, has been detected in tissues targeted by obesity. Yet, inhibition of XOR in pre-clinical and clinical studies generally failed to support a causal role for excess sUA in IR and CVD. The lack of efficacy of XOR inhibitors strongly suggests that UA is a marker of, rather than a direct contributory factor for, cardiometabolic diseases. Validation of the function of other purines will require a paradigm shift, from a "UA-centric" view to a more granular assessment of the entire purine network and its interaction with other pathways.

Plasma versus Erythrocyte Vitamin E in Renal Transplant Recipients, and Duality of Tocopherol Species

Redox imbalance is an adverse on-going phenomenon in renal transplant recipients (RTR). Vitamin E has important antioxidant properties that counterbalance its deleterious effects. However, plasma vitamin E affinity with lipids challenges interpretation of its levels. To test the hypothesis that erythrocyte membranes represent a lipids-independent specimen to estimate vitamin E status, we performed a cross-sectional study in a cohort of adult RTR (n = 113) recruited in a university setting (2015-2018). We compared crude and total lipids-standardized linear regression-derived coefficients of plasma and erythrocyte tocopherol species in relation to clinical and laboratory parameters. Strongly positive associations of fasting lipids with plasma tocopherol became inverse, rather than absent, in total lipids-standardized analyses, indicating potential overadjustment. Whilst, no variables from the lipids domain were associated with the tocopherol species measured from erythrocyte specimens. In relation to inflammatory status and clinical parameters with antioxidant activity, we found associations in directions that are consistent with either beneficial or adverse effects concerning α- or γ-tocopherol, respectively. In conclusion, erythrocytes offer a lipids-independent alternative to estimate vitamin E status and investigate its relationship with parameters over other biological domains. In RTR, α- and γ-tocopherol may serve as biomarkers of relatively lower or higher vulnerability to oxidative stress and inflammation, noticeably in opposite directions.

Uric acid, renal function and risk of hypoglycaemia in Chinese type 2 diabetes patients

BACKGROUND

This study aimed to explore independent associations between serum uric acid and hypoglycaemia, and whether mildly increased serum uric acid exacerbated the association between mild decline in estimated glomerular filtration rate (eGFR) and hypoglycaemia.

METHODS

A cross-sectional survey of 6713 inpatients with type 2 diabetes and eGFR ≥60 mL/min/1.73 m² and admitted to 81 tertiary care hospitals in China was conducted. Self-reported asymptotic hypoglycaemia with plasma glucose ≤3.9 mmol/L, hypoglycaemia episodes with symptoms in 1 month or hypoglycaemia that needed assistance from other people in 3 months before hospitalization was used to define hypoglycaemia. Binary logistic regression was used to estimate odds ratios of serum uric acid for hypoglycaemia. Three measures, that is, relative excess risk due to interaction (RERI), attributable proportion due to interaction and synergy index (S) were used to estimate the effect of mildly decreased eGFR on the association of serum uric acid with hypoglycaemia.

RESULTS

Serum uric acid was associated with hypoglycaemia in an ordinal manner (P for trend <0.01) with an odds ratio of top quartile versus the lowest quartile up to 3.03 (95% confidence interval: 2.13-4.32). The odds ratio of serum uric acid levels ≥ versus <283 µmol/L (i.e. the median) was 1.98 (95% confidence interval:1.58-2.48). Serum uric acid levels ≥ versus <283 µmol/L greatly enhanced the association between mild decline in eGFR (eGFR < 90 mL/min/1.73 m² ) and hypoglycaemia from 0.94 (0.36-2.43) to 3.90 (2.55-5.95), with a significant additive interaction (P < 0.05 for RERI, AP and S).

CONCLUSIONS

Mildly increased serum uric acid was associated with increased risk of hypoglycaemia and enhanced the association between mildly decreased eGFR and hypoglycaemia in type 2 diabetes. Copyright © 2016 John Wiley & Sons, Ltd.

Is Uric Acid a Missing Link between Previous Gestational Diabetes Mellitus and the Development of Type 2 Diabetes at a Later Time of Life?

INTRODUCTION

A high level of uric acid (UA) is a strong, independent risk factor for type 2 diabetes mellitus. The relationship between UA levels and the development of type 2 diabetes in women with previous gestational diabetes mellitus (pGDM) remains unclear. The aim of study was to evaluate the UA levels in pGDM women in relation to their current nutritional status and carbohydrate metabolism.

MATERIAL AND METHODS

199 women with pGDM diagnoses based on oral glucose tolerance tests (OGTTs) 5-12 years previously and a control group of 50 women without pGDM. The assessment included anthropometric parameters, body composition (Tanita SC-330S), current OGTT, insulin resistance index (HOMA-IR), β-cell function (HOMA-%B), HbA1c, lipids, and uric acid.

RESULTS

No differences between groups were found in terms of age, time from the index pregnancy, anthropometric parameters, lipids or creatinine levels. The incidences of overweight and obesity were similar. Carbohydrate abnormalities were more frequent in the pGDM group than the control group (43.2% vs 12.0% p<0.001). The women with pGDM had significantly higher fasting glucose, HbA1c, glucose and insulin levels in the OGTTs, but similar HOMA-IR values. Their UA levels were significantly higher (258±58 vs 230±50 μmol/L, p<0.005) and correlated with BMI and the severity of carbohydrate disorders. The normal weight and normoglycemic pGDM women also demonstrated higher UA levels than a similar control subgroup (232±48 vs 208±48 μmol/L, p<0.05). Multivariate analysis revealed significant correlations of UA level with BMI (β = 0.38, 95% CI 0.25-0.51, p<0.0001), creatinine level (β = 0.23, 95% CI 0.11-0.35, p<0.0005), triglycerides (β = 0.20, 95% CI 0.07-0.33, p<0.005) and family history of diabetes (β = 0.13, 95% CI 0.01-0.25, p<0.05). In logistic regression analysis, the association between higher UA level (defined as value ≥297 μmol/L) and presence of any carbohydrate metabolism disorder (IFG, IGT or diabetes) was statistically significant (odds ratio 3.62 [95% CI 1.8-7.3], p<0.001).

CONCLUSIONS

Higher UA levels may be associated with the development of type 2 diabetes in pGDM women, also in these with normal body weights.

Serum Urate and Incident Cardiovascular Disease: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

OBJECTIVE

There is controversy about whether serum urate (sUA) predicts future cardiovascular disease (CVD) independently of classical risk factors, and the age at which any prediction starts. We studied the sUA-CVD association among generally healthy adults.

METHODS

CARDIA recruited 5115 black and white individuals aged 18-30 years in 1985-1986 (year-0). Fatal and nonfatal CVD events by year 27 (n = 164) were ascertained during annual contacts and classified using medical records. The association with sUA (year-0, 10, 15 and 20) was modeled using Cox proportional hazards regression, pooling over gender-specific quartiles.

RESULTS

Mean sUA concentration was higher in men than women, but increased over time in both genders. Those with elevated sUA had worse metabolic profiles that substantially deteriorated over time. Adjusting for demographic and lifestyle factors (the minimal model), baseline sUA concentration was positively associated with incident CVD (hazard ratio (HR) per mg/dL = 1.21; 95% confidence interval: 1.05, 1.39; P = 0.005). This positive association attenuated to nonsignificance in the full model accounting simultaneously for classical CVD risk factors (HR = 1.09; 0.94, 1.27; P = 0.24). Both the minimal and full models appeared to show stronger associations (than year-0 sUA) between year-10 sUA and incident CVD (HR = 1.27 and 1.12, respectively), but sUA was not statistically significant in the full model. Despite fewer events, year-15 sUA showed a significant sUA-CVD association pattern, with minimal model association magnitude comparable to year-10, and remained significant in the full model (HR = 1.19; 1.02, 1.40; P = 0.03). Hyperuricemia at year-15 strongly predicted CVD risk (HR = 2.11; 1.34, 3.33; P = 0.001), with some attenuation in the full model (HR = 1.68; P = 0.04).

CONCLUSIONS

sUA may be an early biomarker for CVD in adults entering middle age. The prediction of CVD by sUA appeared to strengthen with aging. The potential complex relation of sUA with deterioration of a cluster of metabolic abnormalities warrants future exploration.

Highly Prevalent Hyperuricaemia is Associated with Adverse Clinical Outcomes Among Ghanaian Stroke Patients: An Observational Prospective Study

BACKGROUND

Although a direct causal relationship between hyperuricaemia and stroke continues to be debated, strong associations between serum uric acid (SUA) and cerebrovascular disease exist. Very few studies have been conducted to evaluate the frequency and association between this potentially modifiable biomarker of vascular risk and stroke in sub-Saharan Africa. Therefore the aim of this study was to examine the association between hyperuricaemia and the traditional risk factors and the outcomes of stroke in Ghanaian patients.

METHODS

In this prospective observational study, 147 patients presenting with stroke at a tertiary referral centre in Ghana were consecutively recruited. Patients were screened for vascular risk factors and SUA concentrations measured after an overnight fast. Associations between hyperuricaemia and stroke outcomes were analysed using Kaplan-Meier and Cox proportional hazards regression analysis.

RESULTS

The frequency of hyperuricaemia among Ghanaian stroke patients was 46.3%. Non-significant associations were observed between hyperuricaemia and the traditional risk factors of stroke. SUA concentration was positively correlated with stroke severity and associated with early mortality after an acute stroke with unadjusted hazards ratio of 2.3 (1.4 - 4.2, p=0.001). A potent and independent dose-response association between increasing SUA concentration and hazard of mortality was found on Cox proportional hazards regression, aHR (95% CI) of 1.65 (1.14-2.39), p=0.009 for each 100µmol/l increase in SUA.

CONCLUSIONS

Hyperuricaemia is highly frequent and associated with adverse functional outcomes among Ghanaian stroke patients. Further studies are warranted to determine whether reducing SUA levels after a stroke would be beneficial within our setting.

Uricaemia and left ventricular mass in hypertensive patients

BACKGROUND

Both hyperuricaemia and left ventricular (LV) hypertrophy are associated with the metabolic syndrome and increased cardiovascular risk. The relationship between uric acid levels and left ventricular mass in hypertension, however, is unclear. In this study, we have investigated this relationship in hypertensive patients without the metabolic syndrome.

MATERIALS AND METHODS

In a cross-sectional study, 367 nondiabetic, essential hypertensive patients (age 52 ± 14; 194 males and 173 females) free of clinically relevant cardiovascular complications and without the metabolic syndrome were consecutively recruited at a university hypertension clinic. In these patients, we measured plasma levels of uric acid, lipids, glucose and insulin at fast and after an oral glucose load (OGTT), renal function and performed both conventional and tissue Doppler echocardiography.

RESULTS

Hypertensive patients with LV hypertrophy had higher uric acid levels and greater prevalence of hyperuricemia than patients with normal left ventricular mass. Uric acid levels were directly related with fasting and post-OGTT plasma insulin and with the HOMA index and inversely with 24-h creatinine clearance. Uric acid was also significantly and directly related with the left ventricular mass and multivariate regression analysis showed that this relationship was independent from components of the metabolic syndrome and renal function in women, but not in men.

CONCLUSIONS

Elevated uric acid levels are independently related to the left ventricular mass in hypertensive women without the metabolic syndrome. In these patients with a low cardiovascular risk profile, uric acid might contribute to the development of subclinical cardiac damage.

HOMA-IR and the risk of hyperuricemia: a prospective study in non-diabetic Japanese men

AIMS

To examine the relation of insulin resistant status determined by homeostasis model assessment of insulin resistance (HOMA-IR) with the risk of incident hyperuricemia.

METHODS

The study participants included 2071 Japanese men without hyperuricemia and diabetes, aged 35-54 years. The participants had undergone annual heath examinations for 6 years to compare incident hyperuricemia (serum uric acid >416.4μmol/L (7.0mg/dL) and/or taking medication for hyperuricemia) in four groups based on quartiles of baseline HOMA-IR.

RESULTS

During follow-up there were 331 incident cases of hyperuricemia. The hazard ratios for hyperuricemia, compared with HOMA-IR ≤0.66, were 1.42 (95% confidence interval 1.02-1.98) for HOMA-IR 0.67-0.98, 1.20 (0.86-1.68) for HOMA-IR 0.99-1.49 and 1.44 (1.04-1.98) for HOMA-IR ≥1.50 after adjustment for baseline serum uric acid, creatinine, hypercholesterolemia and hypertension status, age, alcohol intake, and smoking and exercise habits. The hazard ratio associated with an increase of one standard deviation in lnHOMA-IR (1.85 as one geometric standard deviation of HOMA-IR) was 1.14 (1.03-1.28) (p for trend=0.02).

CONCLUSIONS

Increased HOMA-IR independently predicted the subsequent development of hyperuricemia. Insulin resistance itself or compensatory hyperinsulinemia may contribute to the development of hyperuricemia.

Positive relationship between total antioxidant status and chemokines observed in adults

Objective. Human evidence is limited regarding the interaction between oxidative stress biomarkers and chemokines, especially in a population of adults without overt clinical disease. The current study aims to examine the possible relationships of antioxidant and lipid peroxidation markers with several chemokines in adults. Methods. We assessed cross-sectional associations of total antioxidant status (TAS) and two lipid peroxidation markers malondialdehyde (MDA) and thiobarbituric acid reactive substances (TBARS) with a suite of serum chemokines, including CXCL-1 (GRO-α), CXCL-8 (IL-8), CXCL-10 (IP-10), CCL-2 (MCP-1), CCL-5 (RANTES), CCL-8 (MCP-2), CCL-11 (Eotaxin-1), and CCL-17 (TARC), among 104 Chinese adults without serious preexisting clinical conditions in Beijing before 2008 Olympics. Results. TAS showed significantly positive correlations with MCP-1 (r = 0.15751, P = 0.0014), MCP-2 (r = 0.3721, P = 0.0001), Eotaxin-1 (r = 0.39598, P < 0.0001), and TARC (r = 0.27149, P = 0.0053). The positive correlations remained unchanged after controlling for age, sex, body mass index, smoking, and alcohol drinking status. No associations were found between any of the chemokines measured in this study and MDA or TBARS. Similar patterns were observed when the analyses were limited to nonsmokers. Conclusion. Total antioxidant status is positively associated with several chemokines in this adult population.

Metabolic risk factors and long-term graft function after paediatric renal transplantation

The aim of this study was to evaluate metabolic risk factors and their impact on long-term allograft function in paediatric renal transplant (RTx) patients. We reviewed the medical records of 210 RTx patients who underwent transplantation at a median age of 4.5 years (range 0.7-18.2) and a median follow-up of 7.0 years (range 1.5-18.0). Data on lipid and glucose metabolism, uric acid levels, weight and blood pressure were collected up to 13 years post-RTx, and the findings were correlated with the measured glomerular filtration rate (GFR). Beyond the first year, GFR showed gradual deterioration with a mean decline of 2.4 ml/min/1.73 m(2)/year. Metabolic syndrome, overweight, hypertension and type 2 diabetes were diagnosed in 14-19%, 20-23%, 62-87% and 3-5% of the patients, respectively. These entities showed only mild association with the concomitant or long-term GFR values. Dyslipidaemia was common and hypertriglyceridaemia associated with a lower GFR at 1.5 and 5 years post-RTx (P = 0.008 and P = 0.017, respectively). Similarly, hyperuricaemia was frequent and associated significantly with GFR (P < 0.001). Except for hyperuricaemia and hypertriglyceridaemia, metabolic risk factors beyond the first postoperative year associated modestly with the long-term kidney graft function in paediatric RTx patients.

Impact of chronic diuretic treatment on glucose homeostasis

BACKGROUND

The use of diuretics for hypertension has been associated with unfavorable changes in cardiovascular risk factors, such as uric acid and glucose tolerance, though the findings in the literature are contradictory.

METHODS

This study investigated whether diuretic use is associated with markers of metabolic and cardiovascular risk, such as insulin-resistance and uric acid, in a cohort of adults without known diabetes and/or atherosclerotic cardiovascular disease. Nine hundred sixty-nine randomly selected participants answered a questionnaire on clinical history and dietary habits. Laboratory blood measurements were obtained in 507 participants.

RESULTS

Previously undiagnosed type 2 diabetes was recognized in 4.2% of participants who were on diuretics (n = 71), and in 2% of those who were not (n = 890; P = 0.53). Pre-diabetes was diagnosed in 38% of patients who were on diuretics, and in 17.4% (P < 0.001) of those who were not. Multivariate analysis showed that insulin-resistance (HOMA-IR) was associated with the use of diuretics (P = 0.002) independent of other well-known predisposing factors, such as diet, physical activity, body mass index, and waist circumference. The use of diuretics was also independently associated with fasting plasma glucose concentrations (P = 0.001) and uric acid concentrations (P = 0.01).

CONCLUSIONS

The use of diuretics is associated with insulin-resistance and serum uric acid levels and may contribute to abnormal glucose tolerance.

The uric acid metabolism pathway as a therapeutic target in hyperuricemia related to metabolic syndrome

INTRODUCTION

Uric acid (UA) increase is considered an important risk factor for the development of cardiovascular disease (CVD) favoring oxidative stress and endothelial dysfunction and is also involved in metabolic syndrome (MS) pathophysiology.

AREAS COVERED

Insulin has a physiological action on renal tubules, causing a reduction in UA clearance, what could explain the hyperuricemia found in MS. On the other hand, it was also hypothesized a causal role of UA in fructose-induced MS. Moreover, it has been suggested that higher UA levels predict the development of MS. MS subjects present a redox imbalance and UA participates in this process. UA can contribute to oxidative stress present in MS; however, it has also an important role in the antioxidant defense system. Although UA may have a protective effect due to its antioxidant properties, it is clear that the dominant effect of UA in MS is deleterious. All-cause mortality and CVD have been shown to be increased with higher UA levels.

EXPERT OPINION

It is extremely important to prescribe drugs which concomitantly decrease hyperuricemia and improve co-morbidities associated with hyperuricemia. Long-term studies to verify the consequences of decreasing UA concentration below current recommendations in asymptomatic patients are needed.

Allopurinol as a cardiovascular drug

Cardiovascular disease (CVD) remains the leading cause of death in the United States. There is evidence that shows a direct relationship between an elevated uric acid level and an increased risk of cardiovascular (CV) events, which has set the foundation for the investigation of uric acid-lowering drugs for the treatment of CVD. Although traditionally the cornerstone therapy for gout, allopurinol's ability to be a competitive inhibitor of the key enzyme, xanthine oxidase, needed for uric acid formation, has prompted recent clinical research evaluating allopurinol as a CV drug. Epidemiologic and biochemical studies on uric acid formation have shown that it is not only uric acid itself that leads to worsening prognosis and increased CV events, but also the free radicals and superoxides formed during xanthine oxidase activity. The combination of uric acid formation and formed free radicals could ultimately lead to coronary endothelial dysfunction and worsening of myocardial oxidative stress. Along with preventing uric acid formation, allopurinol also has the ability to behave as a free radical scavenger of the superoxide anions and free radicals released during uric acid formation.Clinical studies have shown that allopurinol improves endothelial dysfunction and subsequently improves the exercise capacity in patients diagnosed with angina pectoris. Allopurinol has also been shown to decrease oxidative stress and ameliorate the morbidity and mortality of congestive heart failure patients by possibly improving mechanoenergetic uncoupling, with the enhancement of myocardial contractility and the left ventricular ejection fraction. This review presents the pharmacologic action of allopurinol on the CV system and describes the effectiveness of allopurinol as a potential drug to treat 2 CVD morbidities: ischemic heart disease and congestive heart failure.

Optimal uric acid threshold to identify insulin resistance in healthy women

BACKGROUND

Identifying insulin-resistant (IR) individuals is an issue of particular interest in the assessment of cardiometabolic risk, but there is no simple way to accomplish this task. Our aims were to determine the relationship between uric acid and insulin resistance and to define the optimal uric acid cutoff to identify insulin resistance in women.

METHODS

A population-based sample of 588 women without cardiovascular diseases, diabetes, or low glomerular filtration rate (GFR) was divided according to uric acid tertiles. Systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting glucose, low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), TG/HDL-C ratio, insulin [fasting plasma insulin (FPI)], and homeostasis model assessment of insulin resistance (HOMA-IR) were compared between the mentioned tertiles. Receiver operating characteristic (ROC) curves were constructed to determinate the optimal cutoff of uric acid and identify IR individuals defined by the top tertile of FPI and HOMA-IR. The same variables were compared using the top tertile of uric acid and the maximum Youden index as cutoffs. The P values were adjusted by age, GFR, and body mass index (BMI) using analysis of covariance (ANCOVA).

RESULTS

FPI, HOMA-IR, and all of the cardiometabolic risk factors increased through uric acid tertiles. Both cutoffs of uric acid, estimated by the top tertile and by ROC, were identical (4.0 mg/dL). FPI, HOMA-IR, SBP, DBP, TG, TG/HDL-C ratio, and fasting glucose were higher, whereas HDL-C was lower in women who had uric acid levels >4.0 mg/dL. All of the differences remained significant after the adjustment by age and GFR.

CONCLUSION

In healthy women, uric acid levels >4.0 mg/dL were associated with all the markers of IR.

Hyperuricemia as a mediator of the proinflammatory endocrine imbalance in the adipose tissue in a murine model of the metabolic syndrome

OBJECTIVE

Hyperuricemia is strongly associated with obesity and metabolic syndrome and can predict visceral obesity and insulin resistance. Previously, we showed that soluble uric acid directly stimulated the redox-dependent proinflammatory signaling in adipocytes. In this study we demonstrate the role of hyperuricemia in the production of key adipokines.

RESEARCH DESIGN AND METHODS

We used mouse 3T3-L1 adipocytes, human primary adipocytes, and a mouse model of metabolic syndrome and hyperuricemia.

RESULTS

Uric acid induced in vitro an increase in the production (mRNA and secreted protein) of monocyte chemotactic protein-1 (MCP-1), an adipokine playing an essential role in inducing the proinflammatory state in adipocytes in obesity. In addition, uric acid caused a decrease in the production of adiponectin, an adipocyte-specific insulin sensitizer and anti-inflammatory agent. Uric acid-induced increase in MCP-1 production was blocked by scavenging superoxide or by inhibiting NADPH oxidase and by stimulating peroxisome-proliferator-activated receptor-γ with rosiglitazone. Downregulation of the adiponectin production was prevented by rosiglitazone but not by antioxidants. In obese mice with metabolic syndrome, we observed hyperuricemia. Lowering uric acid in these mice by inhibiting xanthine oxidoreductase with allopurinol could improve the proinflammatory endocrine imbalance in the adipose tissue by reducing production of MCP-1 and increasing production of adiponectin. In addition, lowering uric acid in obese mice decreased macrophage infiltration in the adipose tissue and reduced insulin resistance.

CONCLUSIONS

Hyperuricemia might be partially responsible for the proinflammatory endocrine imbalance in the adipose tissue, which is an underlying mechanism of the low-grade inflammation and insulin resistance in subjects with the metabolic syndrome.

Effect of oral β-blocker on short and long-term mortality in patients with acute respiratory failure: results from the BASEL-II-ICU study

INTRODUCTION

Acute respiratory failure (ARF) is responsible for about one-third of intensive care unit (ICU) admissions and is associated with adverse outcomes. Predictors of short- and long-term outcomes in unselected ICU-patients with ARF are ill-defined. The purpose of this analysis was to determine predictors of in-hospital and one-year mortality and assess the effects of oral beta-blockers in unselected ICU patients with ARF included in the BASEL-II-ICU study.

METHODS

The BASEL II-ICU study was a prospective, multicenter, randomized, single-blinded, controlled trial of 314 (mean age 70 (62 to 79) years) ICU patients with ARF evaluating impact of a B-type natriuretic peptide- (BNP) guided management strategy on short-term outcomes.

RESULTS

In-hospital mortality was 16% (51 patients) and one-year mortality 41% (128 patients). Multivariate analysis assessed that oral beta-blockers at admission were associated with a lower risk of both in-hospital (HR 0.33 (0.14 to 0.74) P = 0.007) and one-year mortality (HR 0.29 (0.16 to 0.51) P = 0.0003). Kaplan-Meier analysis confirmed the lower mortality in ARF patients when admitted with oral beta-blocker and further shows that the beneficial effect of oral beta-blockers at admission holds true in the two subgroups of patients with ARF related to cardiac or non-cardiac causes. Kaplan-Meier analysis also shows that administration of oral beta-blockers before hospital discharge gives striking additional beneficial effects on one-year mortality.

CONCLUSIONS

Established beta-blocker therapy appears to be associated with a reduced mortality in ICU patients with acute respiratory failure. Cessation of established therapy appears to be hazardous. Initiation of therapy prior to discharge appears to confer benefit. This finding was seen regardless of the cardiac or non-cardiac etiology of respiratory failure.

TRIAL REGISTRATION

clinicalTrials.gov Identifier: NCT00130559.

Serum uric Acid as a predictor for the development of nonalcoholic Fatty liver disease in apparently healthy subjects: a 5-year retrospective cohort study

BACKGROUND/AIMS

This study evaluated the relationship between hyperuricemia and nonalcoholic fatty liver disease (NAFLD) by comparing the incidence rates of NAFLD in relation to serum uric acid levels in apparently healthy subjects during a 5-year period.

METHODS

Among 15,638 healthy Korean subjects who participated in a health-screening program in 2003 and 2008, respectively, 4954 subjects without other risk factors were enrolled in this study. We compared the incidence rates of NAFLD in 2008 with respect to baseline uric acid levels.

RESULTS

In 2003, serum uric acid levels were categorized into the following quartiles: 0.6-3.9, 3.9-4.8, 4.8-5.9, and 5.9-12.6 mg/dL. The incidence of NAFLD in 2008 increased with the level of baseline uric acid (5.6%, 9.8%, 16.2%, and 20.9%, respectively; p<0.05). Multiple logistic regression analysis demonstrated that hyperuricemia was associated with the development of NAFLD. When compared to the subjects in quartile 1, the odds ratio (OR) for the incidence of NAFLD for quartiles 2, 3, and 4 were 1.53 (95% confidence interval [CI], 1.09-2.16; p=0.014], 1.69 (95% CI, 1.17-2.44; p=0.005), and 1.84 (95% CI, 1.25-2.71; p=0.002), respectively.

CONCLUSIONS

High serum uric acid levels appear to be associated with an increased risk of the development of NAFLD.

Metabolic syndrome and mild to moderate chronic kidney disease among minorities

The incidence and prevalence of metabolic syndrome and chronic kidney disease (CKD) are increasing in the US population as a whole, but much more rapidly among ethnic minorities. Recent studies have shown that metabolic syndrome is an independent risk factor for the development of incident CKD in African Americans and American Indians distinct from its impact on cardiovascular and all-cause mortality. The pathogenesis of metabolic syndrome in ethnic minorities often is multifactorial. We review the myriad facets of the impact of the metabolic syndrome on the pathophysiology of CKD in minorities. In addition to classic biochemical and physiologic factors, increasing attention is being drawn to the major role of novel factors such as adiponectin and socioeconomic and cultural factors in the development of obesity and insulin resistance; an understudied area that may modulate clinically relevant consequences of biochemical and pathophysiologic aberrations. We present an integrated pathophysiologic viewpoint that incorporates insights from basic science, socioeconomic inquiry, and clinical studies into a framework for clinical practice and investigation.

Relevance of uric Acid in progression of type 2 diabetes mellitus

Recent studies have introduced serum uric acid (UA) as a potential risk factor for developing diabetes, hypertension, stroke, and cardiovascular diseases. The value of elevated levels of UA in serum as a risk factor for diabetes development is still under scrutiny. Recent data suggest that clearance of UA is being reduced with increase in insulin resistance and UA as a marker of prediabetes period. However, conflicting data related to UA in serum of patients with Type 2 diabetes prompted us to study the urine/serum ratio of UA levels (USRUA) in these patients and healthy controls. All subjects included in the study were free of evidence of hepatitis B or C viral infection or active liver and kidney damage. Patients receiving drugs known to influence UA levels were also excluded from this study. Analysis of glucose and uric acid were performed on Dade Behring analyzer using standard IFCC protocols. Interestingly, our data demonstrated about 2.5 fold higher USRUA values in diabetic patients as compared to control subjects. Furthermore, there was a trend of correlation of USRUA value with the blood glucose levels in diabetic patients, which was more prominent in diabetic men than in women. With aging, levels of uric acid increased in serum of diabetic patients, and this effect was also more profound in male than in female diabetics. In conclusion, this study showed significantly elevated USRUA levels in patients with Type 2 diabetes, a negative USRUA correlation with the blood glucose levels in diabetic patients, and an effect of sex and age on the uric acid levels. Since literature data suggest a strong genetic effect on UA levels, it would be pertinent to perform further, possibly genetic studies, in order to clarify gender and ethnic differences in UA concentrations.

Diagnostic and prognostic value of uric acid in patients with acute dyspnea

BACKGROUND

Uric acid was shown to predict outcome in patients with stable chronic heart failure. Its impact in patients admitted in the Emergency Department with acute dyspnea, however, remains unknown.

METHODS

We prospectively investigated the diagnostic and prognostic value of uric acid in 743 unselected patients presenting to the Emergency Department with acute dyspnea.

RESULTS

Uric acid at admission was higher in patients with acute decompensated heart failure (51% of the cohort) as compared with patients with noncardiac causes of dyspnea (median, 447 micromol/L vs 340 micromol/L, P <.001). The area under the receiver operating characteristic curve for the accuracy to detect acute decompensated heart failure was inferior for uric acid (0.70) than for B-type natriuretic peptide (area under the receiver operating characteristic curve 0.91, P <.001). Patients in the highest uric acid tertile more often required admission to the hospital (92% vs 74% in the first tertile, P <.001) and had higher in-hospital mortality (13% vs 4% in the first tertile, P <.001). Cumulative 24-month mortality rates were 28% in the first, 31% in the second, and 50% in the third tertile (P <.001). After adjustment in multivariable Cox proportional hazard analysis, uric acid predicted 24-month mortality independently of B-type natriuretic peptide (P=.003).

CONCLUSIONS

Our study first shows that uric acid, measured at Emergency Department admission or hospital discharge, is a powerful predictor of long-term outcome in dyspneic patients.

Plasma antioxidant capacity among middle‐aged men: The contribution of uric acid

OBJECTIVE

Although assays of plasma antioxidant capacity encompass interactions between various antioxidants, uric acid concentration can exert a predominant effect on results. Therefore, individual differences in uric acid concentration may explain a many of the differences in antioxidant capacity. The objective of this study was to measure the antioxidant capacity of plasma samples with and without uric acid in order to provide more information about how the concept of antioxidant capacity could be applied.

MATERIAL AND METHODS

Antioxidant capacity was measured using an enhanced chemiluminescence assay, and uric acid was removed from the samples using uricase.

RESULTS

Antioxidant capacity was positively correlated with uric acid concentration, body mass index, waist circumference, abdominal sagittal diameter and the concentrations of insulin and triglycerides. These correlations were not evident when uric acid was eliminated from the sample, but antioxidant capacity was correlated with lipid concentration; this may partly reflect tocopherols that are transported by lipid molecules.

CONCLUSIONS

The significance of the contribution of uric acid to the antioxidant capacity could differ according to the type of study. Antioxidant capacity measurements in cross-sectional studies may be presented both with and without the contribution of uric acid, because the absence of such data complicates interpretation of results when different populations are compared.

[Uric acid predicts type 2 diabetes mellitus in the general population]

INTRODUCTION

Abnormal uric acid levels are considered by some to be a risk factor for metabolic disorders, whereas others consider it to be just a marker. We therefore examined the association between plasma uric acid concentrations and the risk of type 2 diabetes mellitus.

MATERIAL AND METHODS

We undertook a prospective, 8-year study of 411 persons from the general population with no carbohydrate metabolism disorder at the start of the study evaluated by oral glucose overload. The following variables were measured at the beginning and end of the study: uric acid, triglycerides, cholesterol, high-density lipoprotein cholesterol, glucose and insulin in plasma, body mass index and waist-to-hip ratio. The participants were classified according to their plasma uric acid concentration, with a cut-off at the 33rd percentile (men, 291.45 and women, 208.18 micromol/l).

RESULTS

Participants with plasma uric acid concentrations above the 33rd percentile at the start of the study had worse lipid and anthropometric profiles. These persons were at greater risk for carbohydrate disorder at the end of the 8- year follow-up study (relative risk, 1.73; 95% confidence interval, 1.04-2.8). No significant differences were found in age or in the remaining variables studied between these two groups.

CONCLUSIONS

Increased uric acid levels in response to a possible chronic increase in oxidative stress may predict future disorders or complications such as type 2 diabetes in otherwise healthy persons.

Genetics of variation in serum uric acid and cardiovascular risk factors in Mexican Americans

BACKGROUND

Elevated serum uric acid is associated with several cardiovascular disease (CVD) risk factors such as hypertension, inflammation, endothelial dysfunction, insulin resistance, dyslipidemia, and obesity. However, the role of uric acid as an independent risk factor for CVD is not yet clear.

OBJECTIVE

The aim of the study was to localize quantitative trait loci regulating variation in serum uric acid and also establish the relationship between serum uric acid and other CVD risk factors in Mexican Americans (n = 848; men = 310, women = 538) participating in the San Antonio Family Heart Study.

METHODS

Quantitative genetic analysis was conducted using variance components decomposition method, implemented in the software program SOLAR.

RESULTS

Mean +/- SD of serum uric acid was 5.35 +/- 1.38 mg/dl. Univariate genetic analysis showed serum uric acid and other CVD risk markers to be significantly heritable (P < 0.005). Bivariate analysis showed significant correlation of serum uric acid with body mass index, waist circumference, waist/hip ratio, total body fat, plasma insulin, serum triglycerides, high-density lipoprotein cholesterol, C-reactive protein, and granulocyte macrophage-colony stimulating factor (P < 0.05). A genome-wide scan for detecting quantitative trait loci regulating serum uric acid variation showed a significant logarithm of odds (LOD) score of 4.72 (empirical LOD score = 4.62; P < 0.00001) on chromosome 3p26. One LOD support interval contains 25 genes, of which an interesting candidate gene is chemokine receptor 2.

SUMMARY

There is a significant genetic component in the variation in serum uric acid and evidence of pleiotropy between serum uric acid and other cardiovascular risk factors.

Hyperinsulinemia and insulin resistance are independently associated with plasma lipids, uric acid and blood pressure in non-diabetic subjects. The GISIR database

BACKGROUND AND AIMS

We evaluated whether hyperinsulinemia and/or insulin resistance are independently associated with plasma lipids, uric acid and blood pressure in non-diabetic subjects.

METHODS AND RESULTS

A database of non-diabetic Italian subjects has recently been set up using data from hyperinsulinemic euglycemic clamp studies carried out using the standard technique (40 mU per min per square meter of body surface area). In this database we evaluated the relationships between fasting plasma insulin (FPI), glucose metabolized during clamp (M) and plasma levels of triglycerides (TG), high density lipoprotein cholesterol (HDL-C), uric acid (UA) as well as blood pressure (BP) in non-diabetic subjects with fasting plasma glucose <6.1 mmol/l. Parallel analyses were conducted in all subjects in the database (n=1093) and in those with all variables available (n=309). In the univariate analysis both FPI and M were significantly correlated with TG, HDL-C, UA and BP (systolic, diastolic and mean). Multivariate regression analyses including center, sex, age, body mass index (BMI), FPI and M as independent variables showed that: (1) TG and UA were positively correlated with FPI and negatively correlated with M; (2) HDL-C was negatively correlated with FPI and positively correlated with M; and (3) BP was negatively correlated with both FPI and M. Analyses of covariance showed that, after adjusting for center, sex, age and BMI, subjects with isolated hyperinsulinemia or isolated insulin resistance had higher TG and UA and lower HDL-C. Subjects with isolated insulin resistance had also higher BP whereas subjects with isolated hyperinsulinemia had lower BP. Subjects with both defects had a worse profile.

CONCLUSIONS

Hyperinsulinemia and insulin resistance might contribute with distinct and independent mechanisms to the development of several metabolic and hemodynamic disorders often clustering in the same individual. In particular, hypertriglyceridemia, low HDL-cholesterol and hyperuricemia seem to be related to both hyperinsulinemia and insulin resistance, whereas hypertension seems to be related only to insulin resistance.

Uric acid: the oxidant-antioxidant paradox

Uric acid, despite being a major antioxidant in the human plasma, both correlates and predicts development of obesity, hypertension, and cardiovascular disease, conditions associated with oxidative stress. While one explanation for this paradox could be that a rise in uric acid represents an attempted protective response by the host, we review the evidence that uric acid may function either as an antioxidant (primarily in plasma) or pro-oxidant (primarily within the cell). We suggest that it is the pro-oxidative effects of uric acid that occur in cardiovascular disease and may have a contributory role in the pathogenesis of these conditions.

Association of incident gout and mortality in dialysis patients

Previous studies have shown that gout is associated with an increased risk for cardiovascular mortality in the general population, but this has not been well studied in patients with ESRD. In this study, the incidence of gout and its association with mortality was evaluated in 259,209 patients in the United States Renal Data System. Overall, the incidence of gout in the first year of dialysis was 5% and in the first 5 yr was 15.4%. Independent risk factors for gout in adjusted analyses included black race, older age, female gender, hypertension, ischemic heart disease, congestive heart failure, and alcohol use. Factors associated with a lower risk for gout included a history of diabetes, smoking, and peripheral vascular disease. Time-dependent Cox regression analysis suggested that an episode of gout was independently associated with a 1.5-fold increase in mortality risk (adjusted hazard ratio 1.49; 95% confidence interval 1.43 to 1.55). The mechanisms underlying this association require further study.

Decreased levels of uric acid after oral glucose challenge is associated with triacylglycerol levels and degree of insulin resistance

Hyperuricaemia is one of the components of metabolic syndrome. Both oxidative stress and hyperinsulinism are important variables in the genesis of this syndrome and have a close association with uric acid (UA). We evaluated the effect of an oral glucose challenge on UA concentrations. The study included 656 persons aged 18 to 65 years. Glycaemia, insulin, UA and plasma proteins were measured at baseline and 120 min after an oral glucose tolerance test (OGTT). The baseline sample also included measurements of total cholesterol, triacylglycerol (TAG) and HDL-cholesterol. Insulin resistance was calculated with the homeostasis model assessment. UA levels were significantly lower after the OGTT (281·93 (sd92·19)v. 267·48 (sd90·40) μmol/l;P < 0·0001). Subjects with a drop in UA concentrations >40·86 μmol/l (>75th percentile) had higher plasma TAG levels (P = 0·0001), baseline insulin (P = 0·02) and greater insulin resistance (P = 0·034). Women with a difference in plasma concentrations of UA above the 75th percentile had higher baseline insulin levels (P = 0·019), concentration of plasma TAG (P = 0·0001) and a greater insulin resistance index (P = 0·029), whereas the only significant difference in men was the level of TAG. Multiple regression analysis showed that the basal TAG levels, insulin at 120 min, glycaemia at 120 min and waist:hip ratio significantly predicted the variance in the UA difference (r20·077). Levels of UA were significantly lower after the OGTT and the individuals with the greatest decrease in UA levels are those who have greater insulin resistance and higher TAG levels.

Insulin resistance, insulin response, and obesity as indicators of metabolic risk

CONTEXT

Insulin resistance (IR) and obesity, especially abdominal obesity, are regarded as central pathophysiological features of a cluster of cardiovascular risk factors (CVRFs), but their relative roles remain undefined. Moreover, the differential impact of IR viz. insulin response has not been evaluated.

OBJECTIVE

The objective of this study was to dissect out the impact of obesity, abdominal obesity, and IR/insulin response on CVRF.

DESIGN

This was a cross-sectional study.

SETTING

The study was conducted at 21 research centers in Europe.

SUBJECTS

The study included a cohort of 1308 nondiabetic subjects [718 women and 590 men, age 30-60 yr, body mass index (BMI) 17-44 kg.m(-2)].

MAIN OUTCOME MEASURES

We measured IR (by a standardized euglycemic insulin clamp), waist girth, insulin response to an oral glucose tolerance test, and major CVRF, and analyzed their associations by multivariate models and factor analysis.

RESULTS

BMI was positively related to all CVRFs. Waist circumference was related to higher blood pressure and serum triglycerides and lower high-density lipoprotein-cholesterol, IR to reduced glucose tolerance, higher free fatty acids, triglyceride and low-density lipoprotein-cholesterol, and lower high-density lipoprotein-cholesterol, and insulin response to higher heart rate, blood pressure and fasting glucose, and the same dyslipidemic profile as IR (P < or = 0.05 for all). By factor analysis, three main factors (related to IR, age, and fatness, respectively) appeared to underlie this pattern of associations. Each of BMI, waist girth, IR, and insulin response was independently associated with total CVRF load (all P < 0.001).

CONCLUSIONS

When IR, fat mass and distribution, and insulin response are measured simultaneously in a large cohort, no one factor stands out as the sole driving force of the CVRF cluster, each being associated with one or more physiological pathways according to known cause-effect relationships.

Incidence and Risk Factors for Metabolic Syndrome in Korean Male Workers, Ages 30 to 39

PURPOSE

There are few prospective data on the incidence of metabolic syndrome. The goals of this study were to define the incidence of and specific risk factors for metabolic syndrome (MetS) in Korean male workers 30 to 39 years of age.

METHODS

A prospective cohort study was undertaken involving 4,779 male workers, 30 to 39 years of age, who did not take medication for dyslipidemia or have a history of any malignancy at study entry. Subjects were reexamined annually at a university hospital in Seoul, Korea, over a 3-year period between 2002 to August 2005. A modified National Cholesterol Education Program definition of MetS with body mass index was used instead of waist circumference. Cox proportional hazards models were used to calculate adjusted hazard ratios in separate models for MetS.

RESULTS

At the end of the 3-year follow-up period, MetS developed in 708 individuals. The unadjusted incidence density of MetS was 70.5 (95% CI, 65.3 approximately 75.37), and the age-adjusted incidence density of MetS was 76.9 per 1,000 person-years (95% CI, 67.8 approximately 86.1). Among a variety of candidate risk factors, uric acid, weight change, gamma-glutamyltranspeptidase, and alanine aminotransferase were independent risk predictors for MetS.

CONCLUSIONS

The high-incidence density of this MetS in Korea may be an indicator of future increases in diabetes and cardiovascular disease.

Plasma uric acid level and risk for incident hypertension among men

Several studies have found that uric acid (UA) level is associated with an increased risk for hypertension, but the association could be confounded by metabolic factors that were not included in these previous studies. UA level and risk for incident hypertension was examined prospectively among men who participated in the Health Professionals' Follow-up Study. From among men without hypertension at the time blood was collected, 750 participants who developed hypertension during the subsequent 8 yr and 750 age-matched controls were selected. In addition to adjustment for standard hypertension risk factors and renal function, adjustments controlled for fasting insulin, triglyceride, and cholesterol levels. The mean age of participants was 61 yr, and mean plasma UA level was 6.0 mg/dl (SD 1.25 mg/dl). The multivariable relative risk (RR) for a 1-SD increase in UA was 1.02 (95% confidence interval [CI]0.87 to 1.18); the RR comparing the highest with lowest quartile of UA was 1.08 (95% CI 0.71 to 1.63). The multivariable RR associated with a 1-SD increase in UA was 1.38 (95% CI 1.05 to 1.81) for men aged <60 yr and 0.90 (95% CI 0.74 to 1.10) for men >or=60 yr (P = 0.04 for interaction). However, further adjustment for fasting insulin, triglyceride, and cholesterol levels attenuated the results (RR for men <60 yr 1.24; 95% CI 0.93 to 1.66). In conclusion, no independent association between UA level and risk for incident hypertension was found among older men.

[Insulin resistance/hyperinsulinemia associated diseases not included in the metabolic syndrome]

In the past years, in Brazil and in developed countries, obesity has become a major public health problem. It was identified that besides DM2 and metabolic syndrome other clinical entities were associated with insulin resistance. In this review we describe some of these alterations emphasizing nonalcoholic fatty liver disease, but also including polycistic ovary disease, hyperuricemia, chronic renal failure, heart failure, cognitive decline and cancer.

Vanadyl sulfate administration protects the streptozotocin-induced oxidative damage to brain tissue in rats

Diabetes mellitus manifests itself in a wide variety of complications and the symptoms of the disease are multifactorial. The present study was carried out to investigate the effects of vanadyl sulfate on biochemical parameters, enzyme activities and brain lipid peroxidation, glutathione and nonenzymatic glycosylation of normal- and streptozotocin-diabetic rats. Streptozotocin (STZ) was administered as a single dose (65 mg/kg) to induce diabetes. A dose of 100 mg/kg vanadyl sulfate was orally administered daily to STZ-diabetic and normal rats, separately until the end of the experiment, at day 60. In STZ-diabetic group, blood glucose, serum sialic and uric acid levels, serum catalase (CAT) and lactate dehydrogenase (LDH) activities, brain lipid peroxidation (LPO) and nonenzymatic glycosylation (NEG) increased, while brain glutathione (GSH) level and body weight decreased. In the diabetic group given vanadyl sulfate, blood glucose, serum sialic and uric acid levels, serum CAT and LDH activities and brain LPO and NEG levels decreased, but brain GSH and body weight increased. The present study showed that vanadyl sulfate exerted antioxidant effects and consequently may prevent brain damage caused by streptozotocin-induced diabetes.

Is hyperuricemia another facet of the metabolic syndrome?

BACKGROUND

Hyperuricemia is commonly associated with obesity, glucose intolerance, hypertension, dyslipidemia, and atherosclerotic cardiovascular disease. The resemblance of the metabolic syndrome and hyperuricemia has led to the suggestion that hyperuricemia is a part of the metabolic syndrome. The purpose of this study is to examine the contribution of uric acid (UA) as an additional component of the metabolic syndrome in middle-aged men.

METHODS

In total, 393 male participants, aged 45-60 years, were recruited from a professional health evaluation program. Anthropometric measurements and blood pressure (BP) were taken after an overnight fast. Fasting blood samples were collected for the measurements of glucose, UA, and lipid profile. Logistic regression models were fitted to examine the relationship between UA and the diagnosis of metabolic syndrome. Factor analysis was performed to explore the relationship between UA and the components of the metabolic syndrome.

RESULTS

The diagnosis of the metabolic syndrome was significantly associated with waist circumference (WC), glucose, triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), systolic BP, and liver enzyme levels, but not associated with UA levels. The sensitivity of hyperuricemia (serum UA > or = 7.0 mg/dL) for the diagnosis of the metabolic syndrome was 58.0% and the specificity was 55.3%. In factor analysis, UA aggregated with body mass index, WC, glucose, log TG, and HDL-C as a metabolic factor. Systolic and diastolic BP were loaded on a second factor separately. The model loaded with UA explained a similar proportion of the total variance (56.9%), as did the model loaded without UA (62.5%).

CONCLUSION

Our results suggest that the contribution of UA as an additional component of the syndrome seems to be insignificant. We propose that hyperuricemia might not be an important facet for the understanding of the underlying structure of the metabolic syndrome.

Coronary flow reserve and coronary microvascular functions are strongly related to serum uric acid concentrations in healthy adults

BACKGROUND

Uric acid is a well known antioxidant; however, the relationship between serum uric acid levels and oxidative stress-caused disorders including cardiovascular diseases is not clear yet. Transthoracic Doppler echocardiographic measurement of coronary flow reserve is a useful tool to investigate coronary flow reserve and coronary microvascular functions. In this study, we investigated the possible association between serum uric acid concentrations and coronary flow reserve in healthy adults.

METHODS

One hundred healthy volunteers with normal uric acid levels, between 18 and 55 years of age, were included in this study. The study group was divided into two with regard to the serum uric acid levels. Coronary diastolic peak flow velocities were measured at baseline and after dipyridamole infusion (0.56 mg/kg over 4 min) using echocardiography.

RESULTS

Coronary flow reserve and hyperemic mean peak flow velocity were significantly greater in participants with lower serum uric acid concentrations (< or =234 micromol/l for women, < or =302 micromol/l for men) than in those with higher serum uric acid concentrations (>234 micromol/l for women, >302 micromol/l for men) (2.91+/-0.5 vs. 2.47+/-0.5, P<0.001; 66.8+/-11.4 vs. 61.1+/-16.5, P=0.04). The baseline mean peak flow velocity was significantly greater in participants with higher serum uric acid concentrations than in those with lower serum uric acid concentrations (24.7+/-4.1 vs. 23.1+/-2.4, P=0.02).

CONCLUSION

Lower serum uric acid concentrations might be regarded as indicative of coronary microvascular and conductance vessel functionality.