Figure 1. The arginine-to-ornithine ratio as a surrogate marker for arginase activity, its association with pulmonary hypertension (PHT) and correlation with arginase activity.
A. The arginine-to-ornithine ratio (Arg/Orn) in normal controls (Control, n=36) vs. patients with SCD (n=209). B. Arginine-to-ornithine ratio in sickle cell patients with a tricuspid regurgitant jet velocity (TRV) by echocardiography 2.5-2.9 m/s (mild PHT) vs. patients with a TRV ≥ 3.0 m/s (severe PHT). C. Plasma arginase activity (μmol/ml/hr) in normal controls (Control, n=36) vs. patients with sickle cell disease (SCD, n=140). D. Correlation of plasma arginase activity to the arginine-to-ornithine ratio.