(A) Explant nephrectomy performed on Day 5. There is extravasation of red cells and fibrin in the muscular wall and thrombosis of the renal artery (H&E ×100). (B) Explant nephrectomy. Glomerular capillary thrombi and thickening and endothelial swelling in adjacent arteriole (H&E ×200). (C) Kinetics of kallikrein activation by negatively charged molecules. Patient serum (30 μl) or control human serum (30 μl) was incubated with 20 μl of oversulfated glycosaminoglycans (OS-GAG) at a final concentration of 0, 2, 20 and 200 μg/ml at 37°C for 5 min. Kallikrein amidolytic activity was assessed by addition of 150 μl of 50 mM N-Benzoyl-Pro-Phe-Arg-p-nitroanilide hydrochloride chromogenic substrate. O.D. readings were taken every minute for 60 min. The auto-activated kallikrein activities (without OS-GAG induction) in patient serum suggest the presence of a negatively charged contact system inducer in the patient's blood.Acute renal allograft thrombosis in 'seronegative' antiphospholipid syndrome. Akilesh S, Jendrisak M, Zhang L, Lewis JS, Liapis H - NDT plus (2009). Not Altered. CC.