OBJECTIVETo investigate the impact of pre-operative uric acid on acute kidney injury (AKI) after cardiac surgery in elderly patients.

METHODSClinical data were collected from 936 elderly patients (age ≥ 60 years) undergoing cardiac surgery with cardiopulmonary bypass in Guangdong General Hospital between January 2005 and May 2011. The baseline serum creatinine was defined as the latest serum creatinine before surgery, and AKI was diagnosed according to RIFLE criteria. Patients were divided into three groups according to the sex-specific cutoff values of serum uric acid tertiles (group A: ≤ 384.65 µmol/L in men, and ≤ 354.00 µmol/L in women; group B:384.66-476.99 µmol/L in men and 354.01-437.96 µmol/L in women; group C: ≥ 477.00 µmol/L in men and ≥ 437.97 µmol/L in women). Multivariate logistic regression analysis was used to analyze the independent risk factors for AKI.

RESULTSAmong 936 elderly patients, 576 cases (61.5%) developed AKI. Mean uric acid concentration was higher in AKI patients than in Non-AKI patients ( (436.6 ± 119.1) µmol/L vs. (398.0 ± 107.2) µmol/L, P < 0.001). The incidence of AKI was 56.1% (175/312) in group A, 56.3% (175/311) in group B, 72.2% (226/313) in group C (P < 0.001). Multiple logistic regression analysis showed that, after adjusted for age, gender, co-morbidities(hypertension, diabetes mellitus, cerebrovascular disease, chronic obstructive pulmonary disease), previous cardiac surgery, eGFR<60 ml×min(-1) ×1.73 m(-2), heart function ≥ 3 (NYHA), positive urine protein, combination of coronary artery bypass grafting and valvular surgery, cardiopulmonary bypass operation time, aortic cross-clamping time, pre-operative angiotensin converting enzyme inhibitor or angiotensin II receptor blockers and lipid-lowering drugs use, early postoperative angiotensin converting enzyme inhibitor or angiotensin II receptor blockers, diuretics and digoxin use, post-operation central venous pressure, risk of post operative AKI was significantly higher in group C than in group A (OR:1.897, 95%CI: 1.270-2.833, P = 0.002).

CONCLUSIONPre-operative elevated uric acid is an independent risk factor of AKI after cardiac surgery in elderly patients.

Acute Kidney Injury ; etiology ; Aged ; Angiotensin Receptor Antagonists ; Angiotensin-Converting Enzyme Inhibitors ; Cardiac Surgical Procedures ; adverse effects ; Cardiopulmonary Bypass ; Coronary Artery Bypass ; Female ; Humans ; Incidence ; Kidney Function Tests ; Male ; Middle Aged ; Predictive Value of Tests ; Risk Factors ; Uric Acid ; blood

Objective:To explore any effect of transcranial direct current stimulation (tDCS) on neurons, behavior, cerebral blood flow (CBF), vascular regeneration, and the expression of vascular endothelial growth factor (VEGF) and CD34 protein in rats modeling cerebral infarction.Methods:Thirty-two adult male Sprague-Dawley rats were randomly divided into a sham surgery group (Sham group), a model group (modeled with middle cerebral artery occlusion, MCAO group), an anode transcranial direct current stimulation group (A-tDCS group), and a cathode transcranial direct current stimulation group (C-tDCS group), each of 8. MCAO models were established in the rats of the MCAO, A-tDCS and C-tDCS groups using thread fixation. Twenty-four hours after successful modeling, both the Sham and MCAO groups were connected with electrodes without current stimulation, while the A-tDCS and C-tDCS groups were given 20 minutes of 200μA anodic or cathodic electrical stimulation daily, 5 days a week for 12 days. Before and 24 hours after the modeling, and then after the 12 days of treatment, the four groups received Longa neurobehavioral scoring. Moreover, three days after the modeling as well as after the 12 days of treatment, changes in CBF were observed using MRI. Any blood vessel regeneration was observed using immunofluorescence methods, and the expression of VEGF and CD34 proteins were detected using western blotting.Results:The rats in the MCAO, A-tDCS and C-tDCS groups exhibited various degrees of neurological deficit after the modeling. After the 12 days of treatment the average neurobehavioral scores of the A-tDCS and C-tDCS groups were significantly lower than that of the MCAO group, with the A-tDCS group′s average significantly lower than that of the C-tDCS group. Three days after the modeling, 3D-arterial spin labeling scanning showed a significant decrease in CBF around the ischemic lesion in the MCAO, A-tDCS and C-tDCS groups, but that had increased to varying degrees after 12 days of treatment. The changes in the A-tDCS and C-tDCS groups were significantly larger than in the MCAO group on average, with the former group improving significantly more than the latter. After the 12 days of treatment, new vascularization and the expression of VEGF and CD34 proteins were significantly higher in the A-tDCS and C-tDCS groups than in the MCAO group, with the change in the former group again significantly greater than in the latter.Conclusions:tDCS can relieve the symptoms of neurological deficits in rats with cerebral infarction, promote vascular regeneration, CBF, and expression of VEGF and CD34 proteins. Anodic is superior to cathodic stimulation.