Impact of the conversion of Brazilian woodland savanna (cerradão) to pasture and Eucalyptus plantations on soil nitrogen mineralization.

The Brazilian savanna (Cerrado) has been extensively converted to croplands, pastures and forestry plantations, and the deforestation frontier continues expanding. Land conversion may cause critical changes in soil functioning, yet very little is still known about the impact of Cerrado conversion on nutrient cycling and soil fertility. Here, we addressed this knowledge gap by investigating the effects of the woodland cerrado (cerradão) conversion into pastures and Eucalyptus plantations on nitrogen availability and mineralization potential, considering a wide range of spatial and temporal variability due to soil depth, site conditions, and seasonal variation.

Postoperative atrial fibrillation after cardiac surgery: who should receive chemoprophylaxis?

To evaluate arrhythmogenic risk factors associated with greater incidence of postoperative atrial fibrillation (POAF) in patients undergoing cardiac surgery (CABG and/or valvular surgery) in order to identify those more prone to the development of this arrhythmia for possible chemoprophylaxis. Sixty-six patients who underwent elective cardiac surgery were assessed. The following risk factors for the development of POAF were correlated: advanced age, valvular heart disease (VHD), left atrial (LA) enlargement, left ventricular dysfunction (LVD), electrolyte imbalance (EI), previous CABG, prior use and withdrawal of beta-blockers (BB) and/or digitalis 24 hours before surgery).

Prevention of atrial fibrillation with moderate doses of amiodarone in the postoperative period of cardiac surgery is safe and effective in patients with high risk for developing this arrhythmia.

Objective: To assess if prophylaxis with moderate doses of amiodarone in the postoperative period of cardiac surgery (coronary artery bypass grafting and/or valve surgery), reduces the incidence of atrial fibrillation in patients with high risk for developing this arrhythmia.

Methods: A randomized and prospective clinical study involving 68 patients who underwent elective cardiac surgery. Mean age was 64 years and 59% of participants were males.