-Habitual marijuana smoking is associated with inflammation and atypia of airway epithelium accompanied by symptoms of chronic bronchitis. We hypothesized that ⌬ 9 -tetrahydrocannabinol (THC), the primary psychoactive component of marijuana, might contribute to these findings by impairing cellular energetics and mitochondrial function. To test this hypothesis, we examined particulate smoke extracts from marijuana cigarettes, tobacco cigarettes, and placebo marijuana (0% THC) cigarettes for their effects on the mitochondrial function of A549 cells in vitro. Only extracts prepared from marijuana cigarettes altered mitochondrial staining by the potentiometric probe JC-1. With the use of a cross-flow, nose-only inhalation system, rats were then exposed for 20 min to whole marijuana smoke and examined for its effects on airway epithelial cells. Inhalation of marijuana smoke produced lung tissue concentrations of THC that were 8 -10 times higher than those measured in blood (75 Ϯ 38 ng/g wet wt tissue vs. 9.2 Ϯ 2.0 ng/ml), suggesting high local exposure. Intratracheal infusion of JC-1 immediately following marijuana smoke exposure revealed a diffuse decrease in lung cell JC-1 red fluorescence compared with tissue from unexposed or placebo smoke-exposed rats. Exposure to marijuana smoke in vivo also decreased JC-1 red fluorescence (54% decrease, P Ͻ 0.01) and ATP levels (75% decrease, P Ͻ 0.01) in single-cell preparations of tracheal epithelial cells. These results suggest that inhalation of marijuana smoke has deleterious effects on airway epithelial cell energetics that may contribute to the adverse pulmonary consequences of marijuana smoking.

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Milia are benign, superficial keratinaceous cysts that present as fine, small white papules. Milia en plaque is a rare, challenging-to-treat variant most often seen in the posterior auricular region. A total of 9 cases of milia en plaque have been reported in the pediatric literature to date. We report a case of milia en plaque of the nose in a 7-yearold boy, a novel site of involvement in the pediatric population, and successful treatment with the use of topical tretinoin. Topical retinoids offer an effective treatment option for the management of milia en plaque in the pediatric population. Pediatrics 2014;133:e1373-e1376 AUTHORS:

Since these drugs are used widely in the pediatric transplantation population, this report serves to heighten awareness of this debilitating phenomenon, and to stress the importance of exercising caution when sirolimus and tacrolimus are administered in combination to pediatric patients.

The authors have indicated no significant interest with commercial supporters.

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