Mammalian target of rapamycin (mTOR) is activated in cutaneous vascular malformations in vivo.

BACKGROUND: Vascular malformation signaling pathways are the least understood out of all cutaneous endothelial lesions. The overexpression of Akt is known to cause vascular malformations in endothelial cells of mice. Since there are no Akt inhibitors approved for clinical use, we examined phosphorylated S6 expression, a downstream target of Akt. Phosphorylated S6 indicates potential sensitivity to rapamycin. METHODS AND RESULTS: Immunohistochemistry for phospho-s6k against phospho-S6 ribosomal protein was performed on specimens of vascular malformations taken from Sturge- Weber patients. Of the specimens, 70.8% were immunopositive for phospho-s6k. CONCLUSION: Endothelial expression of Akt is responsible for tumor responsiveness to rapamycin. We demonstrate that expression of phosphorylated S6 is elevated in specimens. Our findings provide a rationale for clinical trials of rapamycin on Sturge-Weber or Klippel-Trenaunay-Weber patients.

Transapical closure of a pseudoaneurysm of the mitral-aortic intervalvular fibrosa.

Pseudoaneurysm of the mitral-aortic intervalvular fibrosa is a rare but serious sequela of endocarditis or valve replacement surgery. Because open-heart surgery is a high-risk treatment option, alternative methods are sought. We present the case of a 77-year-old man with a noninfected mechanical mitral valve whose pseudoaneurysm was repaired by introducing an occluder device into the defect by a transapical approach. Upon follow-up imaging, the defect was successfully closed. We conclude that percutaneous closure of pseudoaneurysm of the mitral-aortic intervalvular fibrosa is a viable alternative to surgery and that a transapical approach is an appropriate method of access.

Catastrophic systemic embolization from a left atrial myxoma.

We report the fatal course of a left atrial myxoma: its systemic embolization to the coronary, cerebral, renal, and peripheral vascular beds in a 39-year-old woman resulted in rapid clinical deterioration, multiorgan failure, and death. Among reported cases of left atrial myxoma, this degree of embolic burden is exceedingly rare. In addition to reporting the patient's case, we discuss the presentation and diagnosis of possible intracardiac sources of systemic emboli.

Circadian variation in vascular function and regenerative capacity in healthy humans.

BACKGROUND: Progenitor cells (PCs) are mobilized in response to vascular injury to effect regeneration and repair. Recruitment of PCs requires intact nitric oxide (NO) synthesis by endothelial cells, and their number and activity correlate with cardiovascular disease risk burden and future outcomes. Whereas cardiovascular vulnerability exhibits a robust circadian rhythm, the 24-hour variation of PCs and their inter-relation with vascular function remain unknown. We investigated the circadian variation of PCs and vascular function with the hypothesis that this will parallel the pattern observed for cardiovascular events (CVEs). METHODS AND RESULTS: In 15 healthy subjects (9 men, 37±16 years), circulating PCs and vascular function were measured at 8 am, noon, 4 pm, 8 pm, midnight, 4 am (only PCs counts), and 8 am the following day. Circulating PCs were enumerated as mononuclear cells (MNCs; CD45(med)) that express CD34 as well as CD133, and their activity was assessed as the number of colonies formed by culturing MNCs. Vascular function was evaluated by measurement of endothelium-dependent, flow-mediated vasodilation (FMD) of the brachial artery and tonometry-derived indices of arterial stiffness. Higher CD34(+) and CD34(+)/CD133(+) cell counts were observed at 8 pm than any other time of the day (P-ANOVA=0.038 and <0.001; respectively) and were lowest at 8 am. PC colony formation was highest at midnight (P-ANOVA=0.045) and lowest in the morning hours. FMD was highest at midnight and lowest at 8 am and 8 pm, and systemic arterial stiffness was greatest at 8 am and lowest at 4 pm and midnight (P-ANOVA=0.03 and 0.01; respectively). CONCLUSION: A robust circadian variation in PC counts and vascular function occurs in healthy humans and both exhibit an unfavorable profile in the morning hours that parallels the preponderance of CVEs at these times. Whether these changes are precipitated by awakening and time-dependent physical activity or governed by the endogenous circadian clock needs to be further investigated.