1 Induction of lipocortin 1 secretion by dexamethasone has been demonstrated, although the secretory mechanism is still unknown. We have studied the effects of 12-tetradecanoyl phorbol 13-acetate (TPA) and/or dexamethasone on the expression, translocation, and secretion of lipocortin 1 in U937 cells. 2 The expression of lipocortin 1 and its mRNA increased during TPA-induced differentiation of U937 cells to a maximum of 1.9 fold and 8.2 fold, respectively, after 48 h. Both the protein and the mRNA levels decreased after 48 h. 3 TPA caused the translocation of lipocortin 1 from the cytosol to the membrane of U937 cells in a time-dependent manner, as determined by Western blot analysis. The translocation was concurrent with the differentiation of the cells. After 48 h of TPA treatment, 82.6+6.5% of lipocortin 1 was present in the membrane fraction compared to 41.6+1.7% in untreated cells. 4 The amount of lipocortin 1 that was externally bound (associated) with the membrane increased to 3.2 fold as the cytosol to membrane translocation of lipocortin 1 increased. 5 Dexamethasone decreased the externally bound lipocortin 1, but had no effect on the cytosol to membrane translocation. 6 This offers a model system with which the function and the secretion mechanism of lipocortin 1 can be studied. Our data is consistent with the hypothesis that the secretory mechanism is through an unknown pathway, involving the translocation of lipocortin 1 from the cytosol to the internal membranes, and then, its secretion to the external membrane.

Amiodarone is widely used to control fatal arrhythmia. However, amiodarone therapy is associated with a relatively high incidence of pulmonary toxicity, up to 5 to 10%. Typical symptoms are nonspecific and often manifest as nonproductive cough, dyspnea and interstitial infiltrates in patients with acute pneumonitis or chronic fibrosis. However, hemoptysis is a very rare symptom of amiodarone pulmonary toxicity. We report a case of amiodarone pulmonary toxicity, who presented with hemoptysis and was successfully treated with the cessation of amiodarone, with review of the relevant literature. (