ANG and pulmonary arterial hypertension: Modified nucleosides can be released into the circulation during stress after cleavage of transfer RNAs (tRNAs) by the ribonuclease angiogenin.21 To determine whether this mechanism was relevant to PAH, we measured plasma angiogenin in a representative subset of age- and sex-matched healthy control subjects and patients with PAH from the discovery analysis (Table V in the online-only Data Supplement).