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Kalakech H.,University of Angers | Kalakech H.,Laboratoire Cardioprotection | Tamareille S.,University of Angers | Tamareille S.,Laboratoire Cardioprotection | And 18 more authors.
Journal of Molecular and Cellular Cardiology | Year: 2013

Remote ischemic preconditioning (RIPC) has emerged as a feasible and attractive therapeutic procedure for heart protection against ischemia/reperfusion (I/R) injury. However, its molecular mechanisms remain poorly understood. Hypoxia inducible factor-1α (HIF-1α) is a transcription factor that plays a key role in the cellular adaptation to hypoxia and ischemia. This study's aim was to test whether RIPC-induced cardioprotection requires HIF-1α upregulation to be effective. In the first study, wild-type mice and mice heterozygous for HIF1a (gene encoding the HIF-1α protein) were subjected to RIPC immediately before myocardial infarction (MI). RIPC resulted in a robust HIF-1α activation in the limb and acute cardioprotection in wild-type mice. RIPC-induced cardioprotection was preserved in heterozygous mice, despite the low HIF-1α expression in their limbs. In the second study, the role of HIF-1α in RIPC was evaluated using cadmium (Cd), a pharmacological HIF-1α inhibitor. Rats were subjected to MI (MI group) or to RIPC immediately prior to MI (R-MI group). Cd was injected 180. min before RIPC (Cd-R-MI group). RIPC induced robust HIF-1α activation in rat limbs and significantly reduced infarct size (IS). Despite Cd's inhibition of HIF-1α activation, RIPC-induced cardioprotection was preserved in the Cd-R-MI group. RIPC applied immediately prior to MI increased HIF-1α expression and attenuated IS in rats and wild-type mice. However, RIPC-induced cardioprotection was preserved in partially HIF1a-deficient mice and in rats pretreated with Cd. When considered together, these results suggest that HIF-1α upregulation is unnecessary in acute RIPC. © 2013 Elsevier Ltd.

Biere L.,laboratoire cardioprotection | Mateus V.,laboratoire cardioprotection | Grall S.,laboratoire cardioprotection | Prunier F.,laboratoire cardioprotection | And 3 more authors.
IRBM | Year: 2014

Objectives: Infarct size is a major surrogate marker for prognosis in the context of myocardial infarction. There is a growing interest in validating a quantitative assessment approach in order to: (1) standardize these analyses; (2) to precise the individual prognosis of our patients. Several methods are available and were tested across their capacity to predict left ventricular (LV) remodeling at three months. Patients and methods: Late gadolinium enhancement-MRI was performed on day 5 and after a period of three months in 92 patients with STEMI. LV volumes and scar parameters were assessed visually (by using a four scale score) and quantitatively on day 5 and at three months. Dichotomous thresholds were defined first visually (VISUAL), then by 2, 5 and 6 standard deviations above remote myocardium, and by the full-width at half-maximum (FWHM) method. Results: All infarct sizing methods showed great relation to LV remodeling at three months (ROC analysis). Univariate predictors of an LV end-systolic volume index (LVESVi) superior to 70 mL/m2 were: heart failure, creatin kinase peak and infarct size at day 5. FWHM was shown to be the best of all quantitative methods. An infarct size superior to 44 grams predicted a LVESVi > 70 mL/m2 with a sensitivity of 90% and a specificity of 92.5%. FWHM reproducibility was good (r = 0.895, P < 0.0001, Bland Altman bias of 0.8 g). Conclusion: In the context of STEMI, FWHM is a tough and reproducible algorithm to quantitatively assess late gadolinium hyperenhancement, greatly related to functional prognosis at three months follow-up. © 2014.

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