Metabolism of 2-phenylethylamine and phenylacetaldehyde by precision-cut guinea pig fresh liver slices.

2-Phenylethylamine is an endogenous constituent of human brain and is implicated in cerebral transmission. It is also found in certain foodstuffs and may cause toxic side-effects in susceptible individuals. Metabolism of 2-phenylethylamine to phenylacetaldehyde is catalyzed by monoamine oxidase and the oxidation of the reactive aldehyde to its acid derivative is catalyzed mainly by aldehyde dehydrogenase and perhaps aldehyde oxidase, with xanthine oxidase having minimal transformation. The present investigation examines the metabolism of 2-phenylethylamine to phenylacetaldehyde in liver slices and compares the relative contribution of aldehyde oxidase, xanthine oxidase and aldehyde dehydrogenase activity in the oxidation of phenylacetaldehyde with precision-cut fresh liver slices in the presence/absence of specific inhibitors of each enzyme. In liver slices, phenylacetaldehyde was rapidly converted to phenylacetic acid. Phenylacetic acid was the main metabolite of 2-phenylethylamine, via the intermediate phenylacetaldehyde. Phenylacetic acid formation was completely inhibited by disulfiram (specific inhibitor of aldehyde dehydrogenase), whereas isovanillin (specific inhibitor of aldehyde oxidase) inhibited acid formation to a lesser extent and allopurinol (specific inhibitor of xanthine oxidase) had little or no effect. Therefore, in liver slices, phenylacetaldehyde is rapidly oxidized by aldehyde dehydrogenase and aldehyde oxidase with little or no contribution from xanthine oxidase.     

Characterization of long‐term outcomes for pediatric patients with epithelioid hemangioma

Epithelioid hemangioma (EH) is a rare benign vascular tumor that occurs in soft tissues and bone and presents between the third and sixth decades of life. Little is known about the clinical course and outcomes of pediatric EH. We report 11 patients diagnosed with EH at a median age of 14.4 years. One patient treated with interferon and one with sirolimus exhibited partial response for >2 years. Although a benign neoplasm, EH is difficult to manage without standard protocols and portends considerable morbidity. Our findings suggest medical management, particularly sirolimus, may benefit these patients; however, long‐term follow‐up is needed.