OBJECTIVES Gastro-oesophageal reflux (GOR)-related aspiration is associated with respiratory disease, but the current "gold standard" investigation, the lipid-laden macrophage index (LLMI), is flawed. A specific marker of GOR-related aspiration should originate in the stomach, but not the lung. An assay to detect gastric pepsin in the bronchoalveolar lavage (BAL) of children was developed and v...

BACKGROUND Endotracheal intubation increases the risk for microaspiration of secretions around the tube cuff. Pepsin has been used as a biomarker for gastric aspiration. Amylase is a newer proposed biomarker for aspiration of oral contents. OBJECTIVE To assess the presence of pepsin and amylase in paired oral-tracheal secretions of adult patients treated with mechanical ventilation. METHODS...

Some patients with idiopathic pulmonary fibrosis experience acute exacerbations in their respiratory status leading to substantial morbidity and mortality. Occult aspiration of gastric contents has been proposed as one possible mechanism leading to these acute exacerbations. We sought to determine whether pepsin, a marker of gastric aspiration, is elevated in bronchoalveolar lavage fluid obtain...

Two bifunctional reagents designed to probe the active site of pepsin and other acid proteinases are described. One of these, the bisdiazoketone 1,1-bis(diazoacetyl)-2-phenylethane inactivates pepsin at pH 5.0 much more rapidly than the corresponding monodiazoketon 1-diazoacetyl-2-phenylethane, whereas the other, the bromodiazoketone dl-1-diazoacetyl-1-bromo-2-phenylethane is less effective in ...

Pepsin-catalyzed transpeptidation was studied by high resolution 75 MHz 13C nuclear magnetic resonance spectroscopy. Enrichment with 13C at the carbonyl carbons of the substrates Leu-Tyr-NH2 and Leu-Leu-NH2 facilitated detection and identification of the transpeptidation and hydrolysis products of enzymic action. Porcine pepsin was found in each case to synthesize and release the tetrapeptide L...