[Malperfusion in aortic dissection: diagnostic problems and therapeutic procedures]

Heme oxygenase 1 induction protects myocardiac cells against hypoxia/reoxygenation-induced apoptosis : The role of JNK/c-Jun/Caspase-3 inhibition and Akt signaling enhancement

BACKGROUND

Although recent studies have found that heme oxygenase (HO)-1 plays an important role in myocardiac cell survival, the precise mechanisms occurring during hypoxia/reoxygenation (H/R) injury remain unclear. Therefore, the aim of this study was to investigate the cytoprotective mechanisms of HO-1 against H/R-induced myocardiac cell apoptosis and to explore whether the Akt signaling pathway contributed to the protection provided by HO-1.

METHODS

Cobalt protoporphyrin (CoPP, a pharmacologic inducer of HO-1) was employed to induce the over-expression of HO-1 before H/R in H9c2 cells. Hoechst staining and flow cytometry were used to examine the extent of apoptosis. Furthermore, the effect of HO-1 on Akt, JNK, and the expression of apoptosis-related proteins (c-JUN and Caspase-3) was determined by Western blotting.

RESULTS

The results showed that over-expressed HO-1 could significantly protect myocardiac cells against H/R-induced apoptosis in H9c2 cells. Furthermore, the protein expression of p‑Akt increased and of p‑JNK decreased in the H/R injury H9c2 cells when treated with CoPP. The apoptosis-related proteins c‑Jun and caspase-3 were both inhibited by over-expression of HO-1. At the same time, retreatment with zinc protoporphyrin (ZnPP, a specific inhibitor of HO-1 enzymatic activity) or LY294002 (an inhibitor of Akt1) reversed the HO-1-induced changes.

CONCLUSION

In summary, our results suggest that HO-1 can decrease H/R-induced myocardiac cell apoptosis; the mechanism may be related to the activation of the Akt signaling pathway and, furthermore, to the inhibition of the JNK/c-Jun/caspase-3 signaling pathway.

Analysis of intimal extent and predictors of renal atrophy in patients with aortic dissection

BACKGROUND

The intimal flap of aortic dissection may extend to the abdominal branches and probably lead to malperfusion syndrome. Renal malperfusion and renal atrophy are significantly related to patient outcomes.

PURPOSE

To study the extent of the intimal flap and predisposing factors for renal atrophy in patients with aortic dissection.

MATERIAL AND METHODS

From January 2001 to June 2008, 176 (137 men, aged 21-86 years, mean 51.9 years) of 225 subjects with aortic dissection and computed tomography (CT) met the inclusion criteria for this study. Of these 176 patients, 35 (19.9%) developed unilateral renal atrophy. A review of the CT was conducted to classify aortic branch vessel perfusion into three types: type 1, in which the branch vessels are perfused exclusively from the true lumen; type 2, in which the branches are perfused from both the true and false lumens; and type 3, in which the branches are perfused exclusively from the false lumen. Variables including age, gender, type of aortic dissection, type of perfusion of the abdominal branches, and the presence of thrombi in the false lumen were analyzed to determine whether these factors were related to the left or right side and global or focal renal atrophy.

RESULTS

Of 880 abdominal branches in 176 patients, 622 (70.7%) were classed as perfusion type 1, 50 (5.7%) as type 2, and 208 (23.6%) as type 3. Type 3 perfusion was most commonly observed in the left renal artery, at a frequency of 31.7% (66/208). Partial thrombosis in the false lumen above the level of the renal arteries was seen in 68.8% of patients; such thrombi and type 3 perfusion of the renal artery were significantly related to renal atrophy. The laterality (left or right) and extent (global or focal) of renal atrophy were not related to age, gender, type of aortic dissection, or perfusion type.

CONCLUSION

Type 3 perfusion is most frequent in the left renal artery, and such perfusion and partial thrombi in the false lumen above the renal arteries are significantly related to the development of renal atrophy.

Mitochondrial permeability transition triggers the release of mtDNA fragments

Fragments of mitochondrial DNA are released from mitochondria upon opening of the mitochondrial permeability transition pore. Cyclosporin A, an inhibitor of pore opening, completely prevented the release of mitochondrial fragments. Induction of mitochondrial permeability transition and subsequent release of the fragments of mitochondrial DNA could be one cause of genomic instability in the cell.