Pneumomediastinum after cocaine use: an unusual aetiology

We describe an interesting case of pneumomediastinum secondary to cocaine abuse. The patient presented with severe chest pain following nasal inhalation of a large quantity of cocaine. Investigations revealed no chest injury; however oesophagitis was proven leading to a possible aetiology of oesophageal microperforation. After conservative management there was spontaneous resolution of the pneumomediastinum.

Angiopoietin-2 confers Atheroprotection in apoE-/- mice by inhibiting LDL oxidation via nitric oxide

Atherosclerosis is promoted by a combination of hypercholesterolemia and vascular inflammation. The function of Angiopoietin (Ang)-2, a key regulator of angiogenesis, in the maintenance of large vessels is unknown. A single systemic administration of Ang-2 adenovirus (AdAng-2) to apoE(-/-) mice fed a Western diet significantly reduced atherosclerotic lesion size ( approximately 40%) and oxidized LDL and macrophage content of the plaques. These beneficial effects were abolished by the inhibition of nitric oxide synthase (NOS). In endothelial cells, endothelial NOS activation per se inhibited LDL oxidation and Ang-2 stimulated NO release in a Tie2-dependent manner to decrease LDL oxidation. These findings demonstrate a novel atheroprotective role for Ang-2 when endothelial cell function is compromised and suggest that growth factors, which stimulate NO release without inducing inflammation, could offer atheroprotection.

Negative regulation of soluble Flt-1 and soluble endoglin release by heme oxygenase-1

BACKGROUND

Preeclampsia is characterized clinically by hypertension and proteinuria. Soluble Flt-1 (sFlt-1; also known as soluble vascular endothelial growth factor receptor-1 [VEGFR-1]) and soluble endoglin (sEng) are elevated in preeclampsia, and their administration to pregnant rats elicits preeclampsia-like symptoms. Heme oxygenase-1 (HO-1) and its metabolite carbon monoxide (CO) exert protective effects against oxidative stimuli. Thus, we hypothesized that HO-1 upregulation may offer protection against preeclampsia by inhibiting sFlt-1 and sEng release.

METHODS AND RESULTS

Preeclamptic villous explants secreted high levels of sFlt-1 and sEng. Adenoviral overexpression of HO-1 in endothelial cells inhibited VEGF-mediated sFlt-1 release and interferon-gamma- and tumor necrosis factor-alpha-induced sEng release, whereas HO-1 inhibition potentiated sFlt-1 and sEng production from endothelial cells and placental villous explants. Consistent with these findings, mice lacking HO-1 produced higher levels of sFlt-1 and sEng compared with wild-type mice. Using selective ligands (VEGF-E and placental growth factor) and a receptor-specific inhibitor (SU-1498), we demonstrated that VEGF-induced sFlt-1 release was VEGFR-2 dependent. Furthermore, CO-releasing molecule-2 (CORM-2) or CO decreased sFlt-1 release and inhibited VEGFR-2 phosphorylation. Treatment of endothelial cells with statins upregulated HO-1 and inhibited the release of sFlt-1, whereas vitamins C and E had no effect.

CONCLUSIONS

The present study demonstrates that the HO-1/CO pathway inhibits sFlt-1 and sEng release, providing compelling evidence for a protective role of HO-1 in pregnancy, and identifies HO-1 as a novel target for the treatment of preeclampsia.