ABC | Volume 111, Nº6, December 2018

Original Article Ferreira et al Uric acid and cardiovascular risk factors Arq Bras Cardiol. 2018; 111(6):833-840 Methods The present cross-sectional study was conducted at the Discipline of Clinical and Experimental Pathophysiology (CLINEX), located at Pedro Ernesto University Hospital, Rio de Janeiro State University. Potential participants were recruited in the waiting room of the Departments of orthopedics, plastic surgery and gynecology. Inclusion criterion was age between 18-55 years. Exclusion criteria were smoking; use of dietary supplements; use of medications susceptible to interfere in body weight, metabolic profile and blood pressure; use of α -adrenergic blocking agents; recent changes (within previous 6 months) in body weight (> 3 kg), in dietary intake and in intensity or frequency of physical exercise; diagnosis of diabetes mellitus, hypertension, dyslipidemia (with drug treatment) and kidney disease; clinical history of thyroid dysfunction, angina pectoris, peripheral vascular disease, peripheral neuropathy, heart failure, liver failure, chronic pulmonary disease, myocardial infarction and stroke; and finger deformity that would prevent the proper use of the sensors necessary to evaluate endothelial function. Pregnant or lactating women were not allowed into the study. Subjects who met eligibility criteria and agreed to take part in the study were scheduled to arrive at the CLINEX Laboratory between 08:00 and 10:00h a.m. after a 12h fasting period and abstinence from alcohol for 3 days. While fasting, they were submitted to clinical, nutritional, laboratory and endothelial function evaluations. Nutritional assessment A semi-quantitative food frequency questionnaire (FFQ) was used to assess the usual dietary intake of energy, proteins, carbohydrates, lipids, cholesterol, fiber and calcium over the previous 6 months. This FFQ containing 80 items and usual portions was developed for the Brazilian population based on commonly consumed foods. 12 Alcohol consumption was considered when reported frequency equaled one or more time per week. Height was measured by a stadiometer accurate to±0.5 cm and weight was obtained with a calibrated scale accurate to ± 0.1 kg (Filizola S.A., São Paulo, SP, Brazil) after participants without shoes and wearing light clothing, attempted to empty their bladder. Body mass index (BMI) was calculated using the standard equation (kg/m 2 ). Waist circumference (WC) was measured in the standing position midway between the lower margin of the last rib and the iliac crest at mid-exhalation. Hip circumference was measured at the widest point of the hip/ buttocks area with the measuring tape parallel to the floor. Waist-to-hip ratio was determined by dividing WC (cm) by hip circumference (cm). Waist-to-height ratio was obtained by dividing WC (cm) by height (cm). The anthropometric measurements were taken twice and mean values were used in all analysis. Laboratory parameters Aliquots of plasma and serum were stored at -80°C as appropriate for laboratory determinations. Laboratory parameters included fasting circulating levels of uric acid, glucose, insulin, urea, creatinine, lipid profile, high-sensitivity C reactive protein (hs-CRP), adiponectin and malondialdehyde (MDA). Serum concentration of uric acid was determined by enzymatic colorimetric method and urea and creatinine by kinetic method. Fasting plasma glucose was measured by hexokinase method. Fasting plasma insulin levels were determined by the enzyme-linked immunosorbent assay (ELISA) method using the commercially available specific kit (EMD Millipore Corporation Billerica, MA, USA). Insulin resistance status was assessed by homeostasis model assessment of insulin resistance (HOMA-IR) index, calculated as fasting insulin (μU/mL) × fasting plasma glucose (mmol/L)/22.5. 13 Total cholesterol and triglycerides (TG) were assessed by enzymatic method (cholesterol oxidase-peroxidase and glycerol phosphate oxidase-peroxidase, respectively). High density lipoprotein (HDL)-cholesterol was determined by a direct method. Lowdensity lipoprotein (LDL)-cholesterol was estimated by Friedewald’s formula. 14 Circulating levels of hs-CRP and adiponectin were chosen as markers of inflammatory state and their serum concentration determined respectively by turbidimetry (BioSystems, Barcelona, Spain) and ELISA (EMD Millipore Corporation Billerica, MA, USA). Serum levels of MDA, regarded as a measure of oxidative stress, were determined by ELISA method using a commercial kit (USCN Life Science Inc., Missouri, USA) . Blood pressure and heart rate Blood pressure and heart rate were recorded after a resting period of 10 minutes by a calibrated automatic sphygmomanometer: OMRON ® Model HEM-742INT (Omron Healthcare, Lake Forest, IL, USA).The first reading was discarded and the mean of 3 consecutive measurements, taken with a 3 – minute interval in the non-dominant arm, was used in the study. An appropriate arm cuff was used and the patient was instructed to stay seated, legs uncrossed, feet on the floor, leaning back in his chair with the arm at heart level, free from tight clothing, supported with the palm facing up and elbow slightly flexed. Endothelial function Endothelial function was evaluated by peripheral artery tonometry (PAT) method, using Endo-PAT 2000 ® , a finger plethysmographic device (Itamar Medical, Caesarea, Israel). This is a non-invasive method that offers the possibility of an easy and rapid assessment of vascular function in which data are analyzed independently of the examiner. Alterations in pulsatile arterial volume detected by PAT have shown good correlation with flow-mediated dilatation measurement. 15 The measurements were performed through fingertip probes placed on both index fingers. A 5 min measurement was taken at baseline. Sequentially, arterial flow was occluded by a cuff applied to the non-dominant arm, and inflated to 60 mmHg above systolic blood pressure, but never below 200 mmHg. The cuff was rapidly deflated after a 5-min occlusion period, to allow reactive hyperemia. The following 5 min were also recorded. The other arm served as a control and the difference between the two arms was used by Endo‑PAT 2000 ® software to automatically calculate the reactive hyperemia index (RHI). 834