Performance of Sokolow-Lyon index in detection of echocardiographically diagnosed left ventricular hypertrophy in a normal Eastern German population - results of the CARLA study

Background: Arterial hypertension is a common disease with high prevalence in the general population. Left ventricular hypertrophy (LVH) is an independent risk factor in arterial hypertension. Electrocardiographic indices like the Sokolow-Lyon index (SLI) are recommended as diagnostic screening methods for LVH. We assessed the diagnostic performance of the SLI in a cohort of a large general population. Methods: We used electrocardiographic and echocardiographic data from the prospective, population-based cohort study CARdio-vascular Disease, Living and Ageing in Halle (CARLA). Linear and logistic regression models were used to assess the association of SLI with LVH. To assess the impact of the body-mass-index (BMI), we performed interaction analyses. Results: AUC of SLI to predict LVH was 55.3 %, sensitivity of the SLI was 5 %, specificity 97 %. We found a significant association of SLI after covariate-adjustment with echocardiographically detected LVH (increase of left-ventricular mass index, LVMI 7.0 g/m(2) per 1 mV increase of SLI, p 30 kg/m(2)) we found the strongest association with an increase of 9.2 g/m(2) per 1 mV. Conclusions: Although statistically significant, relations of SLI and echocardiographic parameters of LVH were weak and mainly driven by the increase in LVIDd, implicating a more eccentric type of LVH in the collective. The relations were strongest when obese subjects were taken into account. Our data do not favour the SLI as a diagnostic screening test to identify patients at risk for LVH, especially in non-obese subjects without eccentric LVH

Divergent siblings: E2F2 and E2F4 but not E2F1 and E2F3 induce DNA synthesis in cardiomyocytes without activation of apoptosis

Proliferation of mammalian cardiomyocytes ceases around birth when a transition from hyperplastic to hypertrophic myocardial growth occurs. Previous studies demonstrated that directed expression of the transcription factor E2F1 induces S-phase entry in cardiomyocytes along with stimulation of programmed cell death. Here, we show that directed expression of E2F2 and E2F4 by adenovirus mediated gene transfer in neonatal cardiomyocytes induced S-phase entry but did not result in an onset of apoptosis whereas directed expression of E2F1 and E2F3 strongly evoked programmed cell death concomitant with cell cycle progression. Although both E2F2 and E2F4 induced S-phase entry only directed expression of E2F2 resulted in mitotic cell division of cardiomyocytes. Expression of E2F5 or a control LacZ-Adenovirus had no effects on cell cycle progression. Quantitative real time PCR revealed that E2F1, E2F2, E2F3, and E2F4 alleviate G0 arrest by induction of cyclinA and E cyclins. Furthermore, directed expression of E2F1, E2F3, and E2F5 led to a transcriptional activation of several proapoptotic genes, which were mitigated by E2F2 and E2F4. Our finding that expression of E2F2 induces cell division of cardiomyocytes along with a suppression of proapoptotic genes might open a new access to improve the regenerative capacity of cardiomyocytes

Directed expression of dominant-negative p73 enables proliferation of cardiomyocytes in mice

Previous studies have shown that p53 plays an important role in maintaining cell cycle arrest of cardiomyocytes, which might account for the inability of human hearts to regenerate adequately after injury. Therefore, inhibition of p53 represents an attractive strategy to restore cell cycle progression in cardiomyocytes although such an approach is hampered by the potential danger of concomitant tumor induction. During normal development, N-terminal truncated isoforms of the p53-related protein p73 are naturally occurring antagonists of p53 and p73, which are not related to tumor induction. We have generated recombinant adenoviruses encoding dominant-interfering p73 (Ad-p73DD) to inhibit p53/p73 in murine hearts at different developmental stages. We found that the expression of p73DD(wt) in newborn mice led to the increase of the relative heart weights after 14 days which is paralleled by a significant increase of proliferating cardiomyocytes as seen by ICC (BrdU-incorporation, phosphorylation of histone3, expression of AuroraB) without induction of apoptosis. Stimulation of cell cycle progression in cardiomyocytes went along with a significant down-regulation of the p53-dependent cdk-inhibitor p21WAF both on mRNA and protein level. Furthermore, mRNA levels and protein expression of D-type cyclins and cyclins A, B2, and E were selectively increased after expression of p73DD. We further show that the cell cycle entry of cardiomyocytes is not restricted to neonatal hearts but is also found in adult mouse hearts 5 days after intramyocardial injection of Ad-p73DD. Taken together we reason that directed expression of dominant-negative p73 might be utilized to stimulate proliferation of cardiomyocytes to improve cardiac regeneration

Activation of AP-1 Contributes to the β-Adrenoceptor–Mediated Myocardial Induction of Interleukin-6

The induction of proinflammatory cytokines in stressed myocardium is considered an innate immune response, but the role of β-adrenergic signaling in this proinflammatory response and the mechanisms of cardioprotection by β-blockers are not fully understood. In the present study, we analyzed interleukin-6 (IL-6) formation and promoter activation in β-adrenoceptor-stimulated neonatal rat cardiomyocytes, in transgenic mice with cardiac overexpression of β1-adrenoceptors, and in failing human myocardium. IL-6 formation and release in cultured cardiomyocytes under β-adrenoceptor stimulation requires the activation of activating protein-1 (AP-1) binding sites and of cAMP response elements (CRE) in the IL-6 promoter, but this release (140 ± 6 pg/mL medium under 10−6 M isoproterenol vs. 81 ± 3 pg/mL unstimulated, P < 0.05) is moderate compared with that under inflammatory stimulation (855 ± 44 pg/mL, endotoxin 0.1μg/mL). Similarly, IL-6 is induced together with CRE- and AP-1 activation in the left ventricle (LV) of β1-transgenic mice before the onset of failure. However, we observed IL-6 induction with activation of NF-κB in addition to CRE and AP-1 in β1-transgenic mice at the age of 22 weeks and in explanted human LV after full development of failure. Treatment with β-blockers lowered myocardial IL-6 as well as AP-1, NF-κB, and CRE activation. Therefore, the activation of AP-1 and CRE is part of β-adrenergic signal transduction for IL-6 induction in nonfailing and failing cardiomyocytes, whereas NF-κB activation contributes only in overloaded failing myocardium