Virus-containing supernatants were centrifuged through 20% sucrose cushion. Concentrated viral sample was placed for 2 min onto a carbon-coated, UV-treated 200 mesh copper grid as described [58] . Sample-containing grids were rinsed 15 s in water, drained off water with filter paper, and stained for 1 min in filtered 1.3% uranyl acetate. Staining solution was drained off by applying filter paper to the edge of the grid. Grids were left to dry before viewing in a JOEL JEM-2000 EXII transmission electron microscope. Images were collected at 20,0006 and 60,0006. Year in review in Intensive Care Medicine 2011: I. Nephrology, epidemiology, nutrition and therapeutics, neurology, ethical and legal issues, experimentals  Acute kidney injury continued to be hot topic in 2011. Early diagnosis remains an issue of increasing importance, with the aim being to install early preventive measures in critically ill patients. Several very promising biomarkers turned out to have serious limitations in specific disease states, e.g. NGAL in septic shock [1, 2] . Cystatin C is another biomarker that is presumed to allow the early detection of small declines in glomerular filtration rate (GFR), but may also reflect tubular damage if measured in the urine. Royakkers et al. [3] investigated both urine and serum cystatin c in a multicentre prospective observational trial including 151 patients, and could not detect any diagnostic value for urinary cystatin c, only a very moderate performance of serum cystatin c for the prediction of AKI (AUC 0.72), and a very poor one for predicting the requirement for renal replacement therapy RRT (renal replacement therapy) (AUC B0. 66) . Serum cystatin C may also be futile as a biomarker for AKI (acute kidney injury) in the setting of renal obstruction [4] .