Image analysis and modeling of cellular organization in micropatterned environments

In experimental cellular biophysics, it has become standard practice to control the shape and organization of adherent cells. For this purpose, micropatterned environments are being used, which are fabricated using techniques from materials science. Thereby, cell variability can be reduced, which facilitates statistical analysis and allows for a detailed comparison to mathematical models. In this thesis we combine image processing with computational modeling and use the normalization properties of micropatterned environments to investigate cellular organization. In the first part, we apply image analysis techniques to study cell shape and internal organization. For this, we first analyze how contractile polymer bundles, so-called stress fibers, determine the shape of adherent cells in two and three dimensions. Next, we investigate the detailed structure of such bundles and quantify their influence on cellular contraction dynamics. In the second part of the thesis we develop different computational modeling approaches to gain deeper understanding into the interplay between cell shape and the microtubule network. We propose models that are based either on stochastic simulations of polymers or on an effective continuum theory for liquid crystals. With these models we can explain experimental results and predict the internal architecture of cells adhering to micropatterned substrates

Mena/VASP and αII-Spectrin complexes regulate cytoplasmic actin networks in cardiomyocytes and protect from conduction abnormalities and dilated cardiomyopathy

BACKGROUND: In the heart, cytoplasmic actin networks are thought to have important roles in mechanical support, myofibrillogenesis, and ion channel function. However, subcellular localization of cytoplasmic actin isoforms and proteins involved in the modulation of the cytoplasmic actin networks are elusive. Mena and VASP are important regulators of actin dynamics. Due to the lethal phenotype of mice with combined deficiency in Mena and VASP, however, distinct cardiac roles of the proteins remain speculative. In the present study, we analyzed the physiological functions of Mena and VASP in the heart and also investigated the role of the proteins in the organization of cytoplasmic actin networks. RESULTS: We generated a mouse model, which simultaneously lacks Mena and VASP in the heart. Mena/VASP double-deficiency induced dilated cardiomyopathy and conduction abnormalities. In wild-type mice, Mena and VASP specifically interacted with a distinct αII-Spectrin splice variant (SH3i), which is in cardiomyocytes exclusively localized at Z- and intercalated discs. At Z- and intercalated discs, Mena and β-actin localized to the edges of the sarcomeres, where the thin filaments are anchored. In Mena/VASP double-deficient mice, β-actin networks were disrupted and the integrity of Z- and intercalated discs was markedly impaired. CONCLUSIONS: Together, our data suggest that Mena, VASP, and αII-Spectrin assemble cardiac multi-protein complexes, which regulate cytoplasmic actin networks. Conversely, Mena/VASP deficiency results in disrupted β-actin assembly, Z- and intercalated disc malformation, and induces dilated cardiomyopathy and conduction abnormalities

H2020 STRATOFLY Project: from Europe to Australia in less than 3 hours

As eluded in previous studies, with special reference to those carried out in the European framework, some innovative high-speed aircraft configurations have now the potential to assure an economically viable high-speed aircraft fleet. They make use of unexploited flight routes in the stratosphere, offering a solution to the presently congested flight paths while ensuring a minimum environmental impact in terms of emitted noise and green-house gases, particularly during stratospheric cruise. However, only a dedicated multi-disciplinary integrated design approach could realize this, by considering airframe architectures embedding the propulsion systems as well as meticulously integrating crucial subsystems. In this context, starting from an in-depth investigation of the current status of the activities, the STRATOFLY project has been funded by the European Commission, under the framework of Horizon 2020 plan, with the aim of assessing the potential of this type of high-speed transport vehicle to reach Technology Readiness Level (TRL) 6 by 2035, with respect to key technological, societal and economical aspects. This paper aims at summarizing the main results achieved so far to solve the main issues related to thermal and structural integrity, low-emissions combined propulsion cycles, subsystems design and integration, including smart energy management, environmental aspects impacting climate change, noise emissions and social acceptance, and economic viability accounting for safety and human factors

Rationale and design of the MULTISTARS AMI Trial: a randomized comparison of immediate versus staged complete revascularization in patients with ST-segment elevation myocardial infarction and multivessel disease

Background: About half of patients with acute ST-segment elevation myocardial infarction (STEMI) present with multivessel coronary artery disease (MVD). Recent evidence supports complete revascularization in these patients. However, optimal timing of non-culprit lesion revascularization in STEMI patients is unknown because dedicated randomized trials on this topic are lacking. Study design: The MULTISTARS AMI trial is a prospective, international, multicenter, randomized, two-arm, open-label study planning to enroll at least 840 patients. It is designed to investigate whether immediate complete revascularization is non-inferior to staged (within 19-45 days) complete revascularization in patients in stable hemodynamic conditions presenting with STEMI and MVD and undergoing primary percutaneous coronary intervention (PCI). After successful primary PCI of the culprit artery, patients are randomized in a 1:1 ratio to immediate or staged complete revascularization. The primary endpoint is a composite of all-cause death, non-fatal myocardial infarction, ischemia-driven revascularization, hospitalization for heart failure, and stroke at 1 year. Conclusions: The MULTISTARS AMI trial tests the hypothesis that immediate complete revascularization is non-inferior to staged complete revascularization in stable patients with STEMI and MVD

Treatments targeting inotropy

Acute heart failure (HF) and in particular, cardiogenic shock are associated with high morbidity and mortality. A therapeutic dilemma is that the use of positive inotropic agents, such as catecholamines or phosphodiesterase-inhibitors, is associated with increased mortality. Newer drugs, such as levosimendan or omecamtiv mecarbil, target sarcomeres to improve systolic function putatively without elevating intracellular Ca2+. Although meta-analyses of smaller trials suggested that levosimendan is associated with a better outcome than dobutamine, larger comparative trials failed to confirm this observation. For omecamtiv mecarbil, Phase II clinical trials suggest a favourable haemodynamic profile in patients with acute and chronic HF, and a Phase III morbidity/mortality trial in patients with chronic HF has recently begun. Here, we review the pathophysiological basis of systolic dysfunction in patients with HF and the mechanisms through which different inotropic agents improve cardiac function. Since adenosine triphosphate and reactive oxygen species production in mitochondria are intimately linked to the processes of excitation-contraction coupling, we also discuss the impact of inotropic agents on mitochondrial bioenergetics and redox regulation. Therefore, this position paper should help identify novel targets for treatments that could not only safely improve systolic and diastolic function acutely, but potentially also myocardial structure and function over a longer-term.Peer reviewe

Towards standardization of echocardiography for the evaluation of left ventricular function in adult rodents : a position paper of the ESC Working Group on Myocardial Function

This work was supported by AIRC IG grant 2016 19032 to S.Z.; FEDER through Compete 2020 –Programa Operacional Competitividade E Internacionalização(POCI), the project DOCNET (norte-01-0145-feder-000003), supported by Norte Portugal regional operational programme (norte 2020), under the Portugal 2020 partnership agreement, through the European Regional Development Fund (ERDF), the project NETDIAMOND (POCI-01-0145-FEDER-016385), supported by European Structural And Investment Funds, Lisbon’s regional operational program 2020 to I.P.F.; grants from FSR-FNRS, FRC (Cliniques Universitaires Saint-Luc) and from Action de Recherche Concertée (UCLouvain) to C.B., E.P.D. and L.B; the ERA-Net-CVD project MacroERA,01KL1706, FP7-Homage N° 305507, and IMI2-CARDIATEAM (N° 821508)to S.H.,the DZHK (German Centre for Cardiovascular Research) and the German Ministry of Research and Education (BMBF)to F.W., T.E. and L.C., the Netherlands Cardiovascular Research Initiative, an initiative with support of the Dutch Heart Foundation, CVON2016-Early HFPEF, 2015-10, CVON She-PREDICTS, grant 2017-21, CVON Arena-PRIME, 2017-18, Flemish Research FoundationFWO G091018N and FWO G0B5930N to S.H.; Federico II University/Ricerca di Ateneo grant to C.G..T.; the European Research Area Networks on Cardiovascular Diseases (ERA-CVD) [LYMIT-DIS 2016, MacroERA], Fonds Wetenschappelijk Onderzoek [1160718N] to I.C; the Deutsche Forschungsgemeinschaft (DFG TH903/20-1, KFO311), the Transregio-SFB INST 95/15641 and the EU Horizon 2020 project Cardioregenix (GA 825670)to T.TPeer reviewedPostprin